Top 100 DevOps Interview Questions You Must Prepare in 2020

Are you a DevOps engineer or thinking of getting into DevOps? Well then, the future is yours. Top research firm Forrester declared 2018 as the ‘Year of Enterprise DevOps’ and estimates that 50% of organisations around the world are implementing DevOps.

The crucial thing to understand is that DevOps is not merely a collection of technologies but rather a way of thinking, a culture. DevOps requires a cultural shift that merges operations with development and demands a linked toolchain of technologies to facilitate collaborative change. Since the DevOps philosophy is still at a very nascent stage, application of DevOps as well as the bandwidth required to adapt and collaborate, varies from organization to organization. However, you can develop a portfolio of DevOps skills that can present you as a perfect candidate for any type of organization.

If you want to develop your DevOps skills in a thoughtful, structured manner and get certified as a DevOps Engineer, we would be glad to help. Once you finish the Edureka DevOps certification course, we promise that you will be able to handle a variety of DevOps roles in the industry.

What are the requirements to become a DevOps Engineer?

When looking to fill out DevOps roles, organisations look for a clear set of skills. The most important of these are:

Experience with infrastructure automation tools like Chef, Puppet, Ansible, SaltStack or Windows PowerShell DSC.
Fluency in web languages like Ruby, Python, PHP or Java.
Interpersonal skills that help you communicate and collaborate across teams and roles.

In order to structure the questions below, I put myself in your shoes. Most of the answers in this blog are written from your perspective, i.e. someone who is a potential DevOps expert.

Version Control System (VCS) Interview Questions

Q1. What is Version control?

This is probably the easiest question you will face in the interview. My suggestion is to first give a definition of Version control. It is a system that records changes to a file or set of files over time so that you can recall specific versions later. Version control systems consist of a central shared repository where teammates can commit changes to a file or set of file. Then you can mention the uses of version control.

Version control allows you to:

Revert files back to a previous state.
Revert the entire project back to a previous state.
Compare changes over time.
See who last modified something that might be causing a problem.
Who introduced an issue and when.

Q2. What are the benefits of using version control?

I will suggest you to include the following advantages of version control:

With Version Control System (VCS), all the team members are allowed to work freely on any file at any time. VCS will later allow you to merge all the changes into a common version.
All the past versions and variants are neatly packed up inside the VCS. When you need it, you can request any version at any time and you’ll have a snapshot of the complete project right at hand.
Every time you save a new version of your project, your VCS requires you to provide a short description of what was changed. Additionally, you can see what exactly was changed in the file’s content. This allows you to know who has made what change in the project.
A distributed VCS like Git allows all the team members to have complete history of the project so if there is a breakdown in the central server you can use any of your teammate’s local Git repository.

Q3. Describe branching strategies you have used.

This question is asked to test your branching experience so tell them about how you have used branching in your previous job and what purpose does it serves, you can refer the below points:

Feature branching: A feature branch model keeps all of the changes for a particular feature inside of a branch. When the feature is fully tested and validated by automated tests, the branch is then merged into master.
Task branching: In this model each task is implemented on its own branch with the task key included in the branch name. It is easy to see which code implements which task, just look for the task key in the branch name.
Release branching: Once the develop branch has acquired enough features for a release, you can clone that branch to form a Release branch. Creating this branch starts the next release cycle, so no new features can be added after this point, only bug fixes, documentation generation, and other release-oriented tasks should go in this branch. Once it is ready to ship, the release gets merged into master and tagged with a version number. In addition, it should be merged back into develop branch, which may have progressed since the release was initiated.

In the end tell them that branching strategies varies from one organization to another, so I know basic branching operations like delete, merge, checking out a branch etc.

Q4. Which VCS tool you are comfortable with?

You can just mention the VCS tool that you have worked on like this: “I have worked on Git and one major advantage it has over other VCS tools like SVN is that it is a distributed version control system.”
Distributed VCS tools do not necessarily rely on a central server to store all the versions of a project’s files. Instead, every developer “clones” a copy of a repository and has the full history of the project on their own hard drive.

Q5. What is Git?

I will suggest that you attempt this question by first explaining about the architecture of git as shown in the below diagram. You can refer to the explanation given below:

Git is a Distributed Version Control system (DVCS). It can track changes to a file and allows you to revert back to any particular change.
Its distributed architecture provides many advantages over other Version Control Systems (VCS) like SVN one major advantage is that it does not rely on a central server to store all the versions of a project’s files. Instead, every developer “clones” a copy of a repository I have shown in the diagram below with “Local repository” and has the full history of the project on his hard drive so that when there is a server outage, all you need for recovery is one of your teammate’s local Git repository.
There is a central cloud repository as well where developers can commit changes and share it with other teammates as you can see in the diagram where all collaborators are commiting changes “Remote repository”.

DevOps Interview Questions

Q6. Explain some basic Git commands?

Below are some basic Git commands:

DevOps Interview Questions

Q7. In Git how do you revert a commit that has already been pushed and made public?

There can be two answers to this question so make sure that you include both because any of the below options can be used depending on the situation:

Remove or fix the bad file in a new commit and push it to the remote repository. This is the most natural way to fix an error. Once you have made necessary changes to the file, commit it to the remote repository for that I will use
git commit -m “commit message”
Create a new commit that undoes all changes that were made in the bad commit.to do this I will use a command
git revert <name of bad commit>

Q8. How do you squash last N commits into a single commit?

There are two options to squash last N commits into a single commit. Include both of the below mentioned options in your answer:

If you want to write the new commit message from scratch use the following command
git reset –soft HEAD~N &&
git commit
If you want to start editing the new commit message with a concatenation of the existing commit messages then you need to extract those messages and pass them to Git commit for that I will use
git reset –soft HEAD~N &&
git commit –edit -m”$(git log –format=%B –reverse .HEAD@{N})”

Q9. What is Git bisect? How can you use it to determine the source of a (regression) bug?

I will suggest you to first give a small definition of Git bisect, Git bisect is used to find the commit that introduced a bug by using binary search. Command for Git bisect is
git bisect <subcommand> <options>
Now since you have mentioned the command above, explain what this command will do, This command uses a binary search algorithm to find which commit in your project’s history introduced a bug. You use it by first telling it a “bad” commit that is known to contain the bug, and a “good” commit that is known to be before the bug was introduced. Then Git bisect picks a commit between those two endpoints and asks you whether the selected commit is “good” or “bad”. It continues narrowing down the range until it finds the exact commit that introduced the change.

Q10. What is Git rebase and how can it be used to resolve conflicts in a feature branch before merge?

According to me, you should start by saying git rebase is a command which will merge another branch into the branch where you are currently working, and move all of the local commits that are ahead of the rebased branch to the top of the history on that branch.
Now once you have defined Git rebase time for an example to show how it can be used to resolve conflicts in a feature branch before merge, if a feature branch was created from master, and since then the master branch has received new commits, Git rebase can be used to move the feature branch to the tip of master.
The command effectively will replay the changes made in the feature branch at the tip of master, allowing conflicts to be resolved in the process. When done with care, this will allow the feature branch to be merged into master with relative ease and sometimes as a simple fast-forward operation.

Q11. How do you configure a Git repository to run code sanity checking tools right before making commits, and preventing them if the test fails?

I will suggest you to first give a small introduction to sanity checking, A sanity or smoke test determines whether it is possible and reasonable to continue testing.
Now explain how to achieve this, this can be done with a simple script related to the pre-commit hook of the repository. The pre-commit hook is triggered right before a commit is made, even before you are required to enter a commit message. In this script one can run other tools, such as linters and perform sanity checks on the changes being committed into the repository.
Finally give an example, you can refer the below script:

#!/bin/sh
files=$(git diff –cached –name-only –diff-filter=ACM | grep ‘.go$’)
if [ -z files ]; then
exit 0
fi
unfmtd=$(gofmt -l $files)
if [ -z unfmtd ]; then
exit 0
fi
echo “Some .go files are not fmt’d”
exit 1

This script checks to see if any .go file that is about to be committed needs to be passed through the standard Go source code formatting tool gofmt. By exiting with a non-zero status, the script effectively prevents the commit from being applied to the repository.

Q12. How do you find a list of files that has changed in a particular commit?

For this answer instead of just telling the command, explain what exactly this command will do so you can say that, To get a list files that has changed in a particular commit use command
git diff-tree -r {hash}
Given the commit hash, this will list all the files that were changed or added in that commit. The -r flag makes the command list individual files, rather than collapsing them into root directory names only.
You can also include the below mention point although it is totally optional but will help in impressing the interviewer.
The output will also include some extra information, which can be easily suppressed by including two flags:
git diff-tree –no-commit-id –name-only -r {hash}
Here –no-commit-id will suppress the commit hashes from appearing in the output, and –name-only will only print the file names, instead of their paths.

Q13. How do you setup a script to run every time a repository receives new commits through push?

There are three ways to configure a script to run every time a repository receives new commits through push, one needs to define either a pre-receive, update, or a post-receive hook depending on when exactly the script needs to be triggered.

Pre-receive hook in the destination repository is invoked when commits are pushed to it. Any script bound to this hook will be executed before any references are updated. This is a useful hook to run scripts that help enforce development policies.
Update hook works in a similar manner to pre-receive hook, and is also triggered before any updates are actually made. However, the update hook is called once for every commit that has been pushed to the destination repository.
Finally, post-receive hook in the repository is invoked after the updates have been accepted into the destination repository. This is an ideal place to configure simple deployment scripts, invoke some continuous integration systems, dispatch notification emails to repository maintainers, etc.

Hooks are local to every Git repository and are not versioned. Scripts can either be created within the hooks directory inside the “.git” directory, or they can be created elsewhere and links to those scripts can be placed within the directory.

Q14. How will you know in Git if a branch has already been merged into master?

I will suggest you to include both the below mentioned commands:
git branch –merged lists the branches that have been merged into the current branch.
git branch –no-merged lists the branches that have not been merged.

Continuous Integration questions

Now, let’s look at Continuous Integration interview questions:

Q1. What is meant by Continuous Integration?

I will advise you to begin this answer by giving a small definition of Continuous Integration (CI). It is a development practice that requires developers to integrate code into a shared repository several times a day. Each check-in is then verified by an automated build, allowing teams to detect problems early.
I suggest that you explain how you have implemented it in your previous job. You can refer the below given example:

DevOps Interview Questions

In the diagram shown above:

Developers check out code into their private workspaces.
When they are done with it they commit the changes to the shared repository (Version Control Repository).
The CI server monitors the repository and checks out changes when they occur.
The CI server then pulls these changes and builds the system and also runs unit and integration tests.
The CI server will now inform the team of the successful build.
If the build or tests fails, the CI server will alert the team.
The team will try to fix the issue at the earliest opportunity.
This process keeps on repeating.

Q2. Why do you need a Continuous Integration of Dev & Testing?

For this answer, you should focus on the need of Continuous Integration. My suggestion would be to mention the below explanation in your answer:
Continuous Integration of Dev and Testing improves the quality of software, and reduces the time taken to deliver it, by replacing the traditional practice of testing after completing all development. It allows Dev team to easily detect and locate problems early because developers need to integrate code into a shared repository several times a day (more frequently). Each check-in is then automatically tested.

Q3. What are the success factors for Continuous Integration?

Here you have to mention the requirements for Continuous Integration. You could include the following points in your answer:

Maintain a code repository
Automate the build
Make the build self-testing
Everyone commits to the baseline every day
Every commit (to baseline) should be built
Keep the build fast
Test in a clone of the production environment
Make it easy to get the latest deliverables
Everyone can see the results of the latest build
Automate deployment

Q4. Explain how you can move or copy Jenkins from one server to another?

I will approach this task by copying the jobs directory from the old server to the new one. There are multiple ways to do that; I have mentioned them below:
You can:

Move a job from one installation of Jenkins to another by simply copying the corresponding job directory.
Make a copy of an existing job by making a clone of a job directory by a different name.
Rename an existing job by renaming a directory. Note that if you change a job name you will need to change any other job that tries to call the renamed job.

Q5. Explain how can create a backup and copy files in Jenkins?

Answer to this question is really direct. To create a backup, all you need to do is to periodically back up your JENKINS_HOME directory. This contains all of your build jobs configurations, your slave node configurations, and your build history. To create a back-up of your Jenkins setup, just copy this directory. You can also copy a job directory to clone or replicate a job or rename the directory.

Q6. Explain how you can setup Jenkins job?

My approach to this answer will be to first mention how to create Jenkins job. Go to Jenkins top page, select “New Job”, then choose “Build a free-style software project”.
Then you can tell the elements of this freestyle job:

Optional SCM, such as CVS or Subversion where your source code resides.
Optional triggers to control when Jenkins will perform builds.
Some sort of build script that performs the build (ant, maven, shell script, batch file, etc.) where the real work happens.
Optional steps to collect information out of the build, such as archiving the artifacts and/or recording javadoc and test results.
Optional steps to notify other people/systems with the build result, such as sending e-mails, IMs, updating issue tracker, etc…

Q7. Mention some of the useful plugins in Jenkins.

Below, I have mentioned some important Plugins:

Maven 2 project
Amazon EC2
HTML publisher
Copy artifact
Join
Green Balls

These Plugins, I feel are the most useful plugins. If you want to include any other Plugin that is not mentioned above, you can add them as well. But, make sure you first mention the above stated plugins and then add your own.

Q8. How will you secure Jenkins?

The way I secure Jenkins is mentioned below. If you have any other way of doing it, please mention it in the comments section below:

Ensure global security is on.
Ensure that Jenkins is integrated with my company’s user directory with appropriate plugin.
Ensure that matrix/Project matrix is enabled to fine tune access.
Automate the process of setting rights/privileges in Jenkins with custom version controlled script.
Limit physical access to Jenkins data/folders.
Periodically run security audits on same.

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Continuous Testing Interview Questions:

Now let’s move on to the Continuous Testing questions.

Q1. What is Continuous Testing?

I will advise you to follow the below mentioned explanation:
Continuous Testing is the process of executing automated tests as part of the software delivery pipeline to obtain immediate feedback on the business risks associated with in the latest build. In this way, each build is tested continuously, allowing Development teams to get fast feedback so that they can prevent those problems from progressing to the next stage of Software delivery life-cycle. This dramatically speeds up a developer’s workflow as there’s no need to manually rebuild the project and re-run all tests after making changes.

Q2. What is Automation Testing?

Automation testing or Test Automation is a process of automating the manual process to test the application/system under test. Automation testing involves use of separate testing tools which lets you create test scripts which can be executed repeatedly and doesn’t require any manual intervention.
Q3. What are the benefits of Automation Testing?

I have listed down some advantages of automation testing. Include these in your answer and you can add your own experience of how Continuous Testing helped your previous company:

Supports execution of repeated test cases
Aids in testing a large test matrix
Enables parallel execution
Encourages unattended execution
Improves accuracy thereby reducing human generated errors
Saves time and money

Q4. How to automate Testing in DevOps lifecycle?

I have mentioned a generic flow below which you can refer to:
In DevOps, developers are required to commit all the changes made in the source code to a shared repository. Continuous Integration tools like Jenkins will pull the code from this shared repository every time a change is made in the code and deploy it for Continuous Testing that is done by tools like Selenium as shown in the below diagram.
In this way, any change in the code is continuously tested unlike the traditional approach.

DevOps Interview Questions

Q5. Why is Continuous Testing important for DevOps?

You can answer this question by saying, “Continuous Testing allows any change made in the code to be tested immediately. This avoids the problems created by having “big-bang” testing left to the end of the cycle such as release delays and quality issues. In this way, Continuous Testing facilitates more frequent and good quality releases.”

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Q6. What are the key elements of Continuous Testing tools?

Key elements of Continuous Testing are:

Risk Assessment: It Covers risk mitigation tasks, technical debt, quality assessment and test coverage optimization to ensure the build is ready to progress toward next stage.
Policy Analysis: It ensures all processes align with the organization’s evolving business and compliance demands are met.
Requirements Traceability: It ensures true requirements are met and rework is not required. An object assessment is used to identify which requirements are at risk, working as expected or require further validation.
Advanced Analysis: It uses automation in areas such as static code analysis, change impact analysis and scope assessment/prioritization to prevent defects in the first place and accomplishing more within each iteration.
Test Optimization: It ensures tests yield accurate outcomes and provide actionable findings. Aspects include Test Data Management, Test Optimization Management and Test Maintenance
Service Virtualization: It ensures access to real-world testing environments. Service visualization enables access to the virtual form of the required testing stages, cutting the waste time to test environment setup and availability.

Q7. Which Testing tool are you comfortable with and what are the benefits of that tool?

Here mention the testing tool that you have worked with and accordingly frame your answer. I have mentioned an example below:
I have worked on Selenium to ensure high quality and more frequent releases.

Some advantages of Selenium are:

It is free and open source
It has a large user base and helping communities
It has cross Browser compatibility (Firefox, chrome, Internet Explorer, Safari etc.)
It has great platform compatibility (Windows, Mac OS, Linux etc.)
It supports multiple programming languages (Java, C#, Ruby, Python, Pearl etc.)
It has fresh and regular repository developments
It supports distributed testing

Q8. What are the Testing types supported by Selenium?

Selenium supports two types of testing:
Regression Testing: It is the act of retesting a product around an area where a bug was fixed.
Functional Testing: It refers to the testing of software features (functional points) individually.

Q9. What is Selenium IDE?

My suggestion is to start this answer by defining Selenium IDE. It is an integrated development environment for Selenium scripts. It is implemented as a Firefox extension, and allows you to record, edit, and debug tests. Selenium IDE includes the entire Selenium Core, allowing you to easily and quickly record and play back tests in the actual environment that they will run in.
Now include some advantages in your answer. With autocomplete support and the ability to move commands around quickly, Selenium IDE is the ideal environment for creating Selenium tests no matter what style of tests you prefer.

Q10. What is the difference between Assert and Verify commands in Selenium?

I have mentioned differences between Assert and Verify commands below:

Assert command checks whether the given condition is true or false. Let’s say we assert whether the given element is present on the web page or not. If the condition is true, then the program control will execute the next test step. But, if the condition is false, the execution would stop and no further test would be executed.
Verify command also checks whether the given condition is true or false. Irrespective of the condition being true or false, the program execution doesn’t halts i.e. any failure during verification would not stop the execution and all the test steps would be executed.

Q11. How to launch Browser using WebDriver?

The following syntax can be used to launch Browser:
WebDriver driver = new FirefoxDriver();
WebDriver driver = new ChromeDriver();
WebDriver driver = new InternetExplorerDriver();

Q12. When should I use Selenium Grid?

For this answer, my suggestion would be to give a small definition of Selenium Grid. It can be used to execute same or different test scripts on multiple platforms and browsers concurrently to achieve distributed test execution. This allows testing under different environments and saving execution time remarkably.

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Configuration Management Interview Questions

Now let’s check how much you know about Configuration Management.

Q1. What are the goals of Configuration management processes?

The purpose of Configuration Management (CM) is to ensure the integrity of a product or system throughout its life-cycle by making the development or deployment process controllable and repeatable, therefore creating a higher quality product or system. The CM process allows orderly management of system information and system changes for purposes such as to:

Revise capability,
Improve performance,
Reliability or maintainability,
Extend life,
Reduce cost,
Reduce risk and
Liability, or correct defects.

Q2. What is the difference between Asset management and Configuration Management?

Given below are few differences between Asset Management and Configuration Management:

DevOps Interview Questions

Q3. What is the difference between an Asset and a Configuration Item?

According to me, you should first explain Asset. It has a financial value along with a depreciation rate attached to it. IT assets are just a sub-set of it. Anything and everything that has a cost and the organization uses it for its asset value calculation and related benefits in tax calculation falls under Asset Management, and such item is called an asset.
Configuration Item on the other hand may or may not have financial values assigned to it. It will not have any depreciation linked to it. Thus, its life would not be dependent on its financial value but will depend on the time till that item becomes obsolete for the organization.

Now you can give an example that can showcase the similarity and differences between both:

Similarity:
Server – It is both an asset as well as a CI.
Difference:
Building – It is an asset but not a CI.
Document – It is a CI but not an asset

Q4. What do you understand by “Infrastructure as code”? How does it fit into the DevOps methodology? What purpose does it achieve?

Infrastructure as Code (IAC) is a type of IT infrastructure that operations teams can use to automatically manage and provision through code, rather than using a manual process.
Companies for faster deployments treat infrastructure like software: as code that can be managed with the DevOps tools and processes. These tools let you make infrastructure changes more easily, rapidly, safely and reliably.

Q5. Which among Puppet, Chef, SaltStack and Ansible is the best Configuration Management (CM) tool? Why?

This depends on the organization’s need so mention few points on all those tools:
Puppet is the oldest and most mature CM tool. Puppet is a Ruby-based Configuration Management tool, but while it has some free features, much of what makes Puppet great is only available in the paid version. Organizations that don’t need a lot of extras will find Puppet useful, but those needing more customization will probably need to upgrade to the paid version.
Chef is written in Ruby, so it can be customized by those who know the language. It also includes free features, plus it can be upgraded from open source to enterprise-level if necessary. On top of that, it’s a very flexible product.
Ansible is a very secure option since it uses Secure Shell. It’s a simple tool to use, but it does offer a number of other services in addition to configuration management. It’s very easy to learn, so it’s perfect for those who don’t have a dedicated IT staff but still need a configuration management tool.
SaltStack is python based open source CM tool made for larger businesses, but its learning curve is fairly low.

Q6. What is Puppet?

I will advise you to first give a small definition of Puppet. It is a Configuration Management tool which is used to automate administration tasks.
Now you should describe its architecture and how Puppet manages its Agents. Puppet has a Master-Slave architecture in which the Slave has to first send a Certificate signing request to Master and Master has to sign that Certificate in order to establish a secure connection between Puppet Master and Puppet Slave as shown on the diagram below. Puppet Slave sends request to Puppet Master and Puppet Master then pushes configuration on Slave.
Refer the diagram below that explains the above description.

DevOps Interview Questions

Q7. Before a client can authenticate with the Puppet Master, its certs need to be signed and accepted. How will you automate this task?

The easiest way is to enable auto-signing in puppet.conf.
Do mention that this is a security risk. If you still want to do this:

Firewall your puppet master – restrict port tcp/8140 to only networks that you trust.
Create puppet masters for each ‘trust zone’, and only include the trusted nodes in that Puppet masters manifest.
Never use a full wildcard such as *.

Q8. Describe the most significant gain you made from automating a process through Puppet.

For this answer, I will suggest you to explain you past experience with Puppet. you can refer the below example:
I automated the configuration and deployment of Linux and Windows machines using Puppet. In addition to shortening the processing time from one week to 10 minutes, I used the roles and profiles pattern and documented the purpose of each module in README to ensure that others could update the module using Git. The modules I wrote are still being used, but they’ve been improved by my teammates and members of the community

Q9. Which open source or community tools do you use to make Puppet more powerful?

Over here, you need to mention the tools and how you have used those tools to make Puppet more powerful. Below is one example for your reference:
Changes and requests are ticketed through Jira and we manage requests through an internal process. Then, we use Git and Puppet’s Code Manager app to manage Puppet code in accordance with best practices. Additionally, we run all of our Puppet changes through our continuous integration pipeline in Jenkins using the beaker testing framework.

Q10. What are Puppet Manifests?

It is a very important question so make sure you go in a correct flow. According to me, you should first define Manifests. Every node (or Puppet Agent) has got its configuration details in Puppet Master, written in the native Puppet language. These details are written in the language which Puppet can understand and are termed as Manifests. They are composed of Puppet code and their filenames use the .pp extension.
Now give an exampl. You can write a manifest in Puppet Master that creates a file and installs apache on all Puppet Agents (Slaves) connected to the Puppet Master.

Q11. What is Puppet Module and How it is different from Puppet Manifest?

For this answer, you can go with the below mentioned explanation:
A Puppet Module is a collection of Manifests and data (such as facts, files, and templates), and they have a specific directory structure. Modules are useful for organizing your Puppet code, because they allow you to split your code into multiple Manifests. It is considered best practice to use Modules to organize almost all of your Puppet Manifests.
Puppet programs are called Manifests which are composed of Puppet code and their file names use the .pp extension.

Q12. What is Facter in Puppet?

You are expected to answer what exactly Facter does in Puppet so according to me, you should say, “Facter gathers basic information (facts) about Puppet Agent such as hardware details, network settings, OS type and version, IP addresses, MAC addresses, SSH keys, and more. These facts are then made available in Puppet Master’s Manifests as variables.”

Q13. What is Chef?

Begin this answer by defining Chef. It is a powerful automation platform that transforms infrastructure into code. Chef is a tool for which you write scripts that are used to automate processes. What processes? Pretty much anything related to IT.
Now you can explain the architecture of Chef, it consists of:

Chef Server: The Chef Server is the central store of your infrastructure’s configuration data. The Chef Server stores the data necessary to configure your nodes and provides search, a powerful tool that allows you to dynamically drive node configuration based on data.
Chef Node: A Node is any host that is configured using Chef-client. Chef-client runs on your nodes, contacting the Chef Server for the information necessary to configure the node. Since a Node is a machine that runs the Chef-client software, nodes are sometimes referred to as “clients”.
Chef Workstation: A Chef Workstation is the host you use to modify your cookbooks and other configuration data.

Q14. What is a resource in Chef?

My suggestion is to first define Resource. A Resource represents a piece of infrastructure and its desired state, such as a package that should be installed, a service that should be running, or a file that should be generated.
You should explain about the functions of Resource for that include the following points:

Describes the desired state for a configuration item.
Declares the steps needed to bring that item to the desired state.
Specifies a resource type such as package, template, or service.
Lists additional details (also known as resource properties), as necessary.
Are grouped into recipes, which describe working configurations.

Q15. What do you mean by recipe in Chef?

For this answer, I will suggest you to use the above mentioned flow: first define Recipe. A Recipe is a collection of Resources that describes a particular configuration or policy. A Recipe describes everything that is required to configure part of a system.
After the definition, explain the functions of Recipes by including the following points:

Install and configure software components.
Manage files.
Deploy applications.
Execute other recipes.

Q16. How does a Cookbook differ from a Recipe in Chef?

The answer to this is pretty direct. You can simply say, “a Recipe is a collection of Resources, and primarily configures a software package or some piece of infrastructure. A Cookbook groups together Recipes and other information in a way that is more manageable than having just Recipes alone.”

Q17. What happens when you don’t specify a Resource’s action in Chef?

My suggestion is to first give a direct answer: when you don’t specify a resource’s action, Chef applies the default action.
Now explain this with an example, the below resource:
file ‘C:UsersAdministratorchef-reposettings.ini’ do
content ‘greeting=hello world’
end
is same as the below resource:
file ‘C:UsersAdministratorchef-reposettings.ini’ do
action :create
content ‘greeting=hello world’
end
because: create is the file Resource’s default action.

Q18. What is Ansible module?

Modules are considered to be the units of work in Ansible. Each module is mostly standalone and can be written in a standard scripting language such as Python, Perl, Ruby, bash, etc… One of the guiding properties of modules is idempotency, which means that even if an operation is repeated multiple times e.g. upon recovery from an outage, it will always place the system into the same state.

Q19. What are playbooks in Ansible?

Playbooks are Ansible’s configuration, deployment, and orchestration language. They can describe a policy you want your remote systems to enforce, or a set of steps in a general IT process. Playbooks are designed to be human-readable and are developed in a basic text language.
At a basic level, playbooks can be used to manage configurations of and deployments to remote machines.

Q20. How do I see a list of all of the ansible_ variables?

Ansible by default gathers “facts” about the machines under management, and these facts can be accessed in Playbooks and in templates. To see a list of all of the facts that are available about a machine, you can run the “setup” module as an ad-hoc action:
Ansible -m setup hostname
This will print out a dictionary of all of the facts that are available for that particular host.

Q21. How can I set deployment order for applications?

WebLogic Server 8.1 allows you to select the load order for applications. See the Application MBean Load Order attribute in Application. WebLogic Server deploys server-level resources (first JDBC and then JMS) before deploying applications. Applications are deployed in this order: connectors, then EJBs, then Web Applications. If the application is an EAR, the individual components are loaded in the order in which they are declared in the application.xml deployment descriptor.

Q22. Can I refresh static components of a deployed application without having to redeploy the entire application?

Yes, you can use weblogic.Deployer to specify a component and target a server, using the following syntax:
java weblogic.Deployer -adminurl http://admin:7001 -name appname -targets server1,server2 -deploy jsps/*.jsp

Q23. How do I turn the auto-deployment feature off?

The auto-deployment feature checks the applications folder every three seconds to determine whether there are any new applications or any changes to existing applications and then dynamically deploys these changes.

The auto-deployment feature is enabled for servers that run in development mode. To disable auto-deployment feature, use one of the following methods to place servers in production mode:

In the Administration Console, click the name of the domain in the left pane, then select the Production Mode checkbox in the right pane.
At the command line, include the following argument when starting the domain’s Administration Server:
-Dweblogic.ProductionModeEnabled=true
Production mode is set for all WebLogic Server instances in a given domain.

Q24. When should I use the external_stage option?

Set -external_stage using weblogic.Deployer if you want to stage the application yourself, and prefer to copy it to its target by your own means.

Ansible and Puppet are two of the most popular configuration management tools among DevOps engineers.

Continuous Monitoring Interview Questions

Let’s test your knowledge on Continuous Monitoring.

Q1. Why is Continuous monitoring necessary?

I will suggest you to go with the below mentioned flow:
Continuous Monitoring allows timely identification of problems or weaknesses and quick corrective action that helps reduce expenses of an organization. Continuous monitoring provides solution that addresses three operational disciplines known as:

continuous audit
continuous controls monitoring
continuous transaction inspection

Q2. What is Nagios?

You can answer this question by first mentioning that Nagios is one of the monitoring tools. It is used for Continuous monitoring of systems, applications, services, and business processes etc in a DevOps culture. In the event of a failure, Nagios can alert technical staff of the problem, allowing them to begin remediation processes before outages affect business processes, end-users, or customers. With Nagios, you don’t have to explain why an unseen infrastructure outage affect your organization’s bottom line.
Now once you have defined what is Nagios, you can mention the various things that you can achieve using Nagios.
By using Nagios you can:

Plan for infrastructure upgrades before outdated systems cause failures.
Respond to issues at the first sign of a problem.
Automatically fix problems when they are detected.
Coordinate technical team responses.
Ensure your organization’s SLAs are being met.
Ensure IT infrastructure outages have a minimal effect on your organization’s bottom line.
Monitor your entire infrastructure and business processes.

This completes the answer to this question. Further details like advantages etc. can be added as per the direction where the discussion is headed.

Q3. How does Nagios works?

I will advise you to follow the below explanation for this answer:
Nagios runs on a server, usually as a daemon or service. Nagios periodically runs plugins residing on the same server, they contact hosts or servers on your network or on the internet. One can view the status information using the web interface. You can also receive email or SMS notifications if something happens.
The Nagios daemon behaves like a scheduler that runs certain scripts at certain moments. It stores the results of those scripts and will run other scripts if these results change.

Now expect a few questions on Nagios components like Plugins, NRPE etc…

Q4. What are Plugins in Nagios?

Begin this answer by defining Plugins. They are scripts (Perl scripts, Shell scripts, etc.) that can run from a command line to check the status of a host or service. Nagios uses the results from Plugins to determine the current status of hosts and services on your network.
Once you have defined Plugins, explain why we need Plugins. Nagios will execute a Plugin whenever there is a need to check the status of a host or service. Plugin will perform the check and then simply returns the result to Nagios. Nagios will process the results that it receives from the Plugin and take the necessary actions.

Q5. What is NRPE (Nagios Remote Plugin Executor) in Nagios?

For this answer, give a brief definition of Plugins. The NRPE addon is designed to allow you to execute Nagios plugins on remote Linux/Unix machines. The main reason for doing this is to allow Nagios to monitor “local” resources (like CPU load, memory usage, etc.) on remote machines. Since these public resources are not usually exposed to external machines, an agent like NRPE must be installed on the remote Linux/Unix machines.

I will advise you to explain the NRPE architecture on the basis of diagram shown below. The NRPE addon consists of two pieces:

The check_nrpe plugin, which resides on the local monitoring machine.
The NRPE daemon, which runs on the remote Linux/Unix machine.

There is a SSL (Secure Socket Layer) connection between monitoring host and remote host as shown in the diagram below.

DevOps Interview Questions

Q6. What do you mean by passive check in Nagios?

According to me, the answer should start by explaining Passive checks. They are initiated and performed by external applications/processes and the Passive check results are submitted to Nagios for processing.
Then explain the need for passive checks. They are useful for monitoring services that are Asynchronous in nature and cannot be monitored effectively by polling their status on a regularly scheduled basis. They can also be used for monitoring services that are Located behind a firewall and cannot be checked actively from the monitoring host.

Q7. When Does Nagios Check for external commands?

Make sure that you stick to the question during your explanation so I will advise you to follow the below mentioned flow. Nagios check for external commands under the following conditions:

At regular intervals specified by the command_check_interval option in the main configuration file or,
Immediately after event handlers are executed. This is in addition to the regular cycle of external command checks and is done to provide immediate action if an event handler submits commands to Nagios.

Q8. What is the difference between Active and Passive check in Nagios?

For this answer, first point out the basic difference Active and Passive checks. The major difference between Active and Passive checks is that Active checks are initiated and performed by Nagios, while passive checks are performed by external applications.
If your interviewer is looking unconvinced with the above explanation then you can also mention some key features of both Active and Passive checks:
Passive checks are useful for monitoring services that are:

Asynchronous in nature and cannot be monitored effectively by polling their status on a regularly scheduled basis.
Located behind a firewall and cannot be checked actively from the monitoring host.

The main features of Actives checks are as follows:

Active checks are initiated by the Nagios process.
Active checks are run on a regularly scheduled basis.

Q9. How does Nagios help with Distributed Monitoring?

The interviewer will be expecting an answer related to the distributed architecture of Nagios. So, I suggest that you answer it in the below mentioned format:
With Nagios you can monitor your whole enterprise by using a distributed monitoring scheme in which local slave instances of Nagios perform monitoring tasks and report the results back to a single master. You manage all configuration, notification, and reporting from the master, while the slaves do all the work. This design takes advantage of Nagios’s ability to utilize passive checks i.e. external applications or processes that send results back to Nagios. In a distributed configuration, these external applications are other instances of Nagios.

Q10. Explain Main Configuration file of Nagios and its location?

First mention what this main configuration file contains and its function. The main configuration file contains a number of directives that affect how the Nagios daemon operates. This config file is read by both the Nagios daemon and the CGIs (It specifies the location of your main configuration file).
Now you can tell where it is present and how it is created. A sample main configuration file is created in the base directory of the Nagios distribution when you run the configure script. The default name of the main configuration file is nagios.cfg. It is usually placed in the etc/ subdirectory of you Nagios installation (i.e. /usr/local/nagios/etc/).

Q11. Explain how Flap Detection works in Nagios?

I will advise you to first explain Flapping first. Flapping occurs when a service or host changes state too frequently, this causes lot of problem and recovery notifications.
Once you have defined Flapping, explain how Nagios detects Flapping. Whenever Nagios checks the status of a host or service, it will check to see if it has started or stopped flapping. Nagios follows the below given procedure to do that:

Storing the results of the last 21 checks of the host or service analyzing the historical check results and determine where state changes/transitions occur
Using the state transitions to determine a percent state change value (a measure of change) for the host or service
Comparing the percent state change value against low and high flapping thresholds

A host or service is determined to have started flapping when its percent state change first exceeds a high flapping threshold. A host or service is determined to have stopped flapping when its percent state goes below a low flapping threshold.

Q12. What are the three main variables that affect recursion and inheritance in Nagios?

According to me the proper format for this answer should be:
First name the variables and then a small explanation of each of these variables:

Name
Use
Register

Then give a brief explanation for each of these variables. Name is a placeholder that is used by other objects. Use defines the “parent” object whose properties should be used. Register can have a value of 0 (indicating its only a template) and 1 (an actual object). The register value is never inherited.

Q13. What is meant by saying Nagios is Object Oriented?

Answer to this question is pretty direct. I will answer this by saying, “One of the features of Nagios is object configuration format in that you can create object definitions that inherit properties from other object definitions and hence the name. This simplifies and clarifies relationships between various components.”

Q14. What is State Stalking in Nagios?

I will advise you to first give a small introduction on State Stalking. It is used for logging purposes. When Stalking is enabled for a particular host or service, Nagios will watch that host or service very carefully and log any changes it sees in the output of check results.
Depending on the discussion between you and interviewer you can also add, “It can be very helpful in later analysis of the log files. Under normal circumstances, the result of a host or service check is only logged if the host or service has changed state since it was last checked.”

Containerization and Virtualization Interview Questions

Let’s see how much you know about containers and VMs.

Q1. What are containers?

My suggestion is to explain the need for containerization first, containers are used to provide consistent computing environment from a developer’s laptop to a test environment, from a staging environment into production.
Now give a definition of containers, a container consists of an entire runtime environment: an application, plus all its dependencies, libraries and other binaries, and configuration files needed to run it, bundled into one package. Containerizing the application platform and its dependencies removes the differences in OS distributions and underlying infrastructure.
DevOps Interview Questions

Q2. What are the advantages that Containerization provides over virtualization?

Below are the advantages of containerization over virtualization:

Containers provide real-time provisioning and scalability but VMs provide slow provisioning
Containers are lightweight when compared to VMs
VMs have limited performance when compared to containers
Containers have better resource utilization compared to VMs

Q3. How exactly are containers (Docker in our case) different from hypervisor virtualization (vSphere)? What are the benefits?

Given below are some differences. Make sure you include these differences in your answer:
DevOps Interview Questions

Q4. What is Docker image?

I suggest that you go with the below mentioned flow:
Docker image is the source of Docker container. In other words, Docker images are used to create containers. Images are created with the build command, and they’ll produce a container when started with run. Images are stored in a Docker registry such as registry.hub.docker.com because they can become quite large, images are designed to be composed of layers of other images, allowing a minimal amount of data to be sent when transferring images over the network.

Q5. What is Docker container?

This is a very important question so just make sure you don’t deviate from the topic. I advise you to follow the below mentioned format:
Docker containers include the application and all of its dependencies but share the kernel with other containers, running as isolated processes in user space on the host operating system. Docker containers are not tied to any specific infrastructure: they run on any computer, on any infrastructure, and in any cloud.
Now explain how to create a Docker container, Docker containers can be created by either creating a Docker image and then running it or you can use Docker images that are present on the Dockerhub.
Docker containers are basically runtime instances of Docker images.

Q6. What is Docker hub?

Answer to this question is pretty direct. Docker hub is a cloud-based registry service which allows you to link to code repositories, build your images and test them, stores manually pushed images, and links to Docker cloud so you can deploy images to your hosts. It provides a centralized resource for container image discovery, distribution and change management, user and team collaboration, and workflow automation throughout the development pipeline.

Q7. How is Docker different from other container technologies?

According to me, below points should be there in your answer:
Docker containers are easy to deploy in a cloud. It can get more applications running on the same hardware than other technologies, it makes it easy for developers to quickly create, ready-to-run containerized applications and it makes managing and deploying applications much easier. You can even share containers with your applications.
If you have some more points to add you can do that but make sure the above the above explanation is there in your answer.

Q8. What is Docker Swarm?

You should start this answer by explaining Docker Swarn. It is native clustering for Docker which turns a pool of Docker hosts into a single, virtual Docker host. Docker Swarm serves the standard Docker API, any tool that already communicates with a Docker daemon can use Swarm to transparently scale to multiple hosts.
I will also suggest you to include some supported tools:

Dokku
Docker Compose
Docker Machine
Jenkins

Q9. What is Dockerfile used for?

This answer according to me should begin by explaining the use of Dockerfile. Docker can build images automatically by reading the instructions from a Dockerfile.
Now I suggest you to give a small definition of Dockerfle. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. Using docker build users can create an automated build that executes several command-line instructions in succession.

Now expect a few questions to test your experience with Docker.

Q10. Can I use json instead of yaml for my compose file in Docker?

You can use json instead of yaml for your compose file, to use json file with compose, specify the filename to use for eg:
docker-compose -f docker-compose.json up

Q11. Tell us how you have used Docker in your past position?

Explain how you have used Docker to help rapid deployment. Explain how you have scripted Docker and used Docker with other tools like Puppet, Chef or Jenkins. If you have no past practical experience in Docker and have past experience with other tools in similar space, be honest and explain the same. In this case, it makes sense if you can compare other tools to Docker in terms of functionality.

Q12. How to create Docker container?

I will suggest you to give a direct answer to this. We can use Docker image to create Docker container by using the below command:
docker run -t -i <image name> <command name>
This command will create and start container.
You should also add, If you want to check the list of all running container with status on a host use the below command:
docker ps -a

Q13. How to stop and restart the Docker container?

In order to stop the Docker container you can use the below command:
docker stop <container ID>
Now to restart the Docker container you can use:
docker restart <container ID>

Q14. How far do Docker containers scale?

Large web deployments like Google and Twitter, and platform providers such as Heroku and dotCloud all run on container technology, at a scale of hundreds of thousands or even millions of containers running in parallel.

Q15. What platforms does Docker run on?

I will start this answer by saying Docker runs on only Linux and Cloud platforms and then I will mention the below vendors of Linux:

Ubuntu 12.04, 13.04 et al
Fedora 19/20+
RHEL 6.5+
CentOS 6+
Gentoo
ArchLinux
openSUSE 12.3+
CRUX 3.0+

Cloud:

Amazon EC2
Google Compute Engine
Microsoft Azure
Rackspace

Note that Docker does not run on Windows or Mac.

Q16. Do I lose my data when the Docker container exits?

You can answer this by saying, no I won’t loose my data when Dcoker container exits. Any data that your application writes to disk gets preserved in its container until you explicitly delete the container. The file system for the container persists even after the container halts.

And, that’s it!

I hope these questions help you crack your DevOps interview. If you have any more questions for us, do mention them in the comments section and we will get back to you.

Originally published at https://www.edureka.co

#devops #docker #interview #kubernetes #interview-questions

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Top 100 DevOps Interview Questions You Must Prepare in 2020

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Android Interview Questions – Get ready for your next interview

Android – one of the hottest technologies, which is having a bright future. Get ready to crack your next interview with the following android interview questions. These interview questions start with basic and cover deep concepts along with advanced topics.

Android Interview Questions for Freshers

1. What is Android?

Android is an open-source mobile operating system that is based on the modified versions of Linux kernel. Though it was mainly designed for smartphones, now it is being used for Tablets, Televisions, Smartwatches, and other Android wearables.

2. Who is the inventor of Android Technology?

The inventors of Android Technology are- Andry Rubin, Nick Sears, and Rich Miner.

3. What is the latest version of Android?

The latest version of Android is Android 10.0, known as Android Q. The upcoming major Android release is Android 11, which is the 18th version of Android. [Note: Keep checking the versions, it is as of June 2020.]

4. How many Android versions can you recall right now?

Till now, there are 17 versions of Android, which have their names in alphabetical order. The 18th version of Android is also going to come later this year. The versions of Android are here:

Android 1.0 – Its release is 23 September 2008.
Android 1.1 – Its release date is 9 February 2009.
Android 1.5 – Its name is Cupcake, Released on 27 April 2009.
Android 1.6 – Its name is Donut, Released on 15 September 2009.
Android 2.0 – Its name is Eclair, Released on 26 October 2009
Android 2.2 – Its name is Froyo, Released on 20 May 2010.
Android 2.3 – Its name is Gingerbread, Released on 06 December 2010.
Android 3.0 – Its name is Honeycomb, Released on 22 February 2011.
Android 4.0 – Its name is Ice Cream Sandwich, Released on 18 October 2011.
Android 4.1 – Its name is Jelly Bean, Released on 9 July 2012.
Android 4.4 – Its name is KitKat, Released on 31 October 2013.
Android 5.0 – Its name is Lollipop, Released on 12 November 2014.
Android 6.0 – Its name is Marshmallow, Released on 5 October 2015.
Android 7.0 – Its name is Nougat, Released on 22 August 2016.
Android 8.0 – Its name is Oreo, Released on 21 August 2017.
Android 9.0 – Its name is Pie, Released on 6 August 2018.
Android 10.0 – Its name is Android Q, Released on 3 September 2019.
Android 11.0 – As of now, it is Android 11.

5. Explain the Android Architecture with its components.

This is a popular android developer interview question

Android Architecture consists of 5 components that are-

a. Linux Kernel: It is the foundation of the Android Architecture that resides at the lowest level. It provides the level of abstraction for hardware devices and upper layer components. Linux Kernel also provides various important hardware drivers that act as software interfaces for hardwares like camera, bluetooth, etc.

b. Native Libraries: These are the libraries for Android that are written in C/C++. These libraries are useful to build many core services like ART and HAL. It provides support for core features.

c. Android Runtime: It is an Android Runtime Environment. Android Operating System uses it during the execution of the app. It performs the translation of the application bytecode into the native instructions. The runtime environment of the device then executes these native instructions.

d. Application Framework: Application Framework provides many java classes and interfaces for app development. And it also provides various high-level services. This complete Application framework makes use of Java.

e. Applications: This is the topmost layer of Android Architecture. It provides applications for the end-user, so they can use the android device and compute the tasks.

6. What are the services that the Application framework provides?

The Android application framework has the following key services-

a. Activity Manager: It uses testing and debugging methods.

b. Content provider: It provides the data from application to other layers.

c. Resource Manager: This provides users access to resources.

d. Notification Manager: This gives notification to the users regarding actions taking place in the background.

e. View System: It is the base class for widgets, and it is also responsible for event handling.

7. What are the important features of Linux Kernel?

The important features of the Linux Kernel are as follows:

a. Power Management: Linux Kernel does power management to enhance and improve the battery life of the device.

b. Memory Management: It is useful for the maximum utilization of the available memory of the device.

c. Device Management: It includes managing all the hardware device drivers. It maximizes the utilization of the available resources.

d. Security: It ensures that no application has any such permission that it affects any other application in order to maintain security.

e. Multi-tasking: Multi-tasking provides the users the ease of doing multiple tasks at the same time.

8. What are the building blocks of an Android Application?

This is a popular android interview question for freshers.

The main components of any Android application are- Activity, Services, Content Provider, and Broadcast Receiver. You can understand them as follows:

a. Activity- It is a class that acts as the entry point representing a single screen to the user. It is like a window to show the user interface.

b. Services- Services are the longest-running component that runs in the background.

c. Content Provider- The content provider is an essential component that allows apps to share data between themselves.

d. Broadcast receivers- Broadcast receiver is another most crucial application component. It helps the apps to receive and respond to broadcast messages from the system or some other application.

9. What are the important components of Android Application?

The Components of Android application are listed below:

Widgets
Intents
Views
Notification
Fragments
Layout XML files
Resources

10. What are the widgets?

Widgets are the variations of Broadcast receivers. They are an important part of home screen customization. They often display some data and also allow users to perform actions on them. Mostly they display the app icon on the screen.

11. Can you name some types of widgets?

Mentioned below are the types of widgets-

a. Informative Widgets: These widgets show some important information. Like, the clock widget or a weather widget.

b. Collective Widgets: They are the collection of some types of elements. For example, a music widget that lets us change, skip, or forward the song.

c. Control Widgets: These widgets help us control the actions within the application through it. Like an email widget that helps check the recent mails.

d. Hybrid Widgets: Hybrid widgets are those that consist of at least two or more types of widgets.

12. What are Intents?

Intents are an important part of Android Applications. They enable communication between components of the same application as well as separate applications. The Intent signals the Android system about a certain event that has occurred.

13. Explain the types of intents briefly?

Intent is of three types that are-

a. Implicit Intents: Implicit intents are those in which there is no description of the component name but only the action.

b. Explicit Intents: In explicit intents, the target component is present by declaring the name of the component.

c. Pending Intents: These are those intents that act as a shield over the Intent objects. It covers the intent objects and grants permission to the external app components to access them.

14. What is a View?

A view is an important building block that helps in designing the user interface of the application. It can be a rectangular box or a circular shape, for example, Text View, Edit Text, Buttons, etc. Views occupy a certain area of the screen, and it is also responsible for event handling. A view is the superclass of all the graphical user interface components.

15. What do you understand by View Group?

It is the subclass of the ViewClass. It gives an invisible container to hold layouts or views. You can understand view groups as special views that are capable of holding other views, that are Child View.

16. What do you understand about Shared Preferences?

It is a simple mechanism for data storage in Android. In this, there is no need to create files, and using APIs, it stores the data in XML files. It stores the data in the pair of key-values. SharedPreferences class lets the user save the values and retrieve them when required. Using SharedPreferences we can save primitive data like- boolean, float, integer, string and long.

17. What is a Notification?

A notification is just like a message that shows up outside the Application UI to provide reminders to the users. They remind the user about a message received, or some other timely information from the app.

18. Give names of Notification types.

There are three types of notifications namely-

a. Toast Notification- This notification is the one that fades away sometime after it pops up.

b. Status Notification- This notification stays till the user takes some action on it.

c. Dialog Notification- This notification is the result of an Active Activity.

19. What are fragments?

A fragment is a part of the complete user interface. These are present in Activity, and an activity can have one or more fragments at the same time. We can reuse a fragment in multiple activities as well.

20. What are the types of fragments?

There are three types of fragments that are: Single Fragment, List Fragment, Fragment Transactions.

Single Transactions can only show a single view for the user.
List Fragments have a special list view feature that provides a list from which the user can select one.
Fragment Transactions are helpful for the transition between one fragment to the other.

Frequently asked Android Interview Questions and Answers

21. What are Layout XML files?

Layout XML files contain the structure for the user interface of the application. The XML file also contains various different layouts and views, and they also specify various GUI components that are there in Activity or fragments.

22. What are Resources in Android Application?

The resources in Android Apps defines images, texts, strings, colors, etc. Everything in resources directory is referenced in the source code of the app so that we can use them.

23. Can you develop Android Apps with languages other than Java? If so, name some.

Yes, there are many languages that we can work with, for the development of Android Applications. To name some, I would say Java, Python, C, C++, Kotlin, C#, Corona/LUA.

24. What are the states of the Activity Lifecycle?

Activity lifecycle has the following four stages-

a. Running State: As soon as the activity starts, it is the first state.

b. Paused State: When some other activity starts without closing the previous one, the running activity turns into the Paused state.

c. Resume State: When the activity opens again after being in pause state, it comes into the Resume State.

d. Stopped State: When the user closes the application or stops using it, the activity goes to the Stopped state.

25. What are some methods of Activity?

The methods of Activity are as follows:

onCreate()
onStart()
onPause()
onRestart()
onResume()
onStop()
onDestroy()

26. How can you launch an activity in Android?

We launch an activity using Intents. For this we need to use intent as follows:

ntent intent_name= new Intent(this, Activity_name.class);
startActivity(intent_name);

27. What is the service lifecycle?

There are two states of a service that are-

a. Started State: This is when the service starts its execution. A Services come in start state only through the startService() method.

b. Bounded State: A service is in the bounded state when it calls the method bindService().

28. What are some methods of Services?

The methods of service are as follows-

onStartCommand()
onBind()
onCreate()
onUnbind()
onDestroy()
onRebind()

29. What are the types of Broadcast?

Broadcasts are of two types that are-

a. Ordered Broadcast: Ordered broadcasts are Synchronous and work in a proper order. It decides the order by using the priority assigned to the broadcasts.

b. Normal Broadcast: These are asynchronous and unordered. They are more efficient as they run unorderly and all at once. But, they lack full utilization of the results.

30. What are useful impotent folders in Android?

The impotent folders in an Android application are-

build.xml- It is responsible for the build of Android applications.
bin/ – The bin folder works as a staging area to wrap the files packages into the APK.
src/ – The src is a folder where all the source files of the project are present.
res/ – The res is the resource folder that stores values of the resources that are used in the application. These resources can be colors, styles, strings, dimensions, etc.
assets/ – It provides a facility to include files like text, XML, fonts, music, and video in the Android application.

31. What are the important files for Android Application when working on Android Studio?

This is an important android studio interview question

There are following three files that we need to work on for an application to work-

a. The AndroidManifest.xml file: It has all the information about the application.

b. The MainActivity.java file: It is the app file that actually gets converted to the dalvik executable and runs the application. It is written in java.

c. The Activity_main.xml file: It is the layout file that is available in the res/layout directory. It is another mostly used file while developing the application.

32. Which database do you use for Android Application development?

The database that we use for Android Applications is SQLite. It is because SQLite is lightweight and specially developed for Android Apps. SQLite works the same way as SQL using the same commands.

33. Tell us some features of Android OS.

The best features of Android include-

Multi-tasking
Support for a great range of languages
Support for split-screen
High connectivity with 5G support
Motion Control

34. Why did you learn Android development?

Learning Android Studio is a good idea because of the following-

It has a low application development cost.
It is an open-source platform.
It has multi-platform support as well as Multi-carrier support.
It is open for customizations.
Android is a largely used operating system throughout the world.

35. What are the different ways of storage supported in Android?

The various storage ways supported in Android are as follows:

Shared Preference
Internal Storage
External Storage
SQLite Databases
Network Connection

36. What are layouts?

Layout is nothing but arrangements of elements on the device screen. These elements can be images, tests, videos, anything. They basically define the structure of the Android user interface to make it user friendly.

37. How many layout types are there?

The type of layouts used in Android Apps are as follows:

Linear Layout
Relative Layout
Constraint Layout
Table Layout
Frame Layout
Absolute Layout
Scrollview layout

38. What is an APK?

An APK stands for Android Package that is a file format of Android Applications. Android OS uses this package for the distribution and installation of the Android Application.

39. What is an Android Manifest file?

The manifest file describes all the essential information about the project application for build tools, Android operating system, and google play. This file is a must for every Android project that we develop, and it is present in the root of the project source set.

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Mikael Abehsera

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Version Control System (VCS) Interview Questions

Q1. What is Version control?

This is probably the easiest question you will face in the interview. My suggestion is to first give a definition of Version control. It is a system that records changes to a file or set of files over time so that you can recall specific versions later. Version control systems consist of a central shared repository where teammates can commit changes to a file or set of file. Then you can mention the uses of version control.

Version control allows you to:

Revert files back to a previous state.
Revert the entire project back to a previous state.
Compare changes over time.
See who last modified something that might be causing a problem.
Who introduced an issue and when.

Q2. What are the benefits of using version control?

I will suggest you to include the following advantages of version control:

With Version Control System (VCS), all the team members are allowed to work freely on any file at any time. VCS will later allow you to merge all the changes into a common version.
All the past versions and variants are neatly packed up inside the VCS. When you need it, you can request any version at any time and you’ll have a snapshot of the complete project right at hand.
Every time you save a new version of your project, your VCS requires you to provide a short description of what was changed. Additionally, you can see what exactly was changed in the file’s content. This allows you to know who has made what change in the project.
A distributed VCS like Git allows all the team members to have complete history of the project so if there is a breakdown in the central server you can use any of your teammate’s local Git repository.

Q3. Describe branching strategies you have used.

This question is asked to test your branching experience so tell them about how you have used branching in your previous job and what purpose does it serves, you can refer the below points:

Feature branching: A feature branch model keeps all of the changes for a particular feature inside of a branch. When the feature is fully tested and validated by automated tests, the branch is then merged into master.
Task branching: In this model each task is implemented on its own branch with the task key included in the branch name. It is easy to see which code implements which task, just look for the task key in the branch name.
Release branching: Once the develop branch has acquired enough features for a release, you can clone that branch to form a Release branch. Creating this branch starts the next release cycle, so no new features can be added after this point, only bug fixes, documentation generation, and other release-oriented tasks should go in this branch. Once it is ready to ship, the release gets merged into master and tagged with a version number. In addition, it should be merged back into develop branch, which may have progressed since the release was initiated.

In the end tell them that branching strategies varies from one organization to another, so I know basic branching operations like delete, merge, checking out a branch etc.

Q4. Which VCS tool you are comfortable with?

You can just mention the VCS tool that you have worked on like this: “I have worked on Git and one major advantage it has over other VCS tools like SVN is that it is a distributed version control system.”
Distributed VCS tools do not necessarily rely on a central server to store all the versions of a project’s files. Instead, every developer “clones” a copy of a repository and has the full history of the project on their own hard drive.

Q5. What is Git?

I will suggest that you attempt this question by first explaining about the architecture of git as shown in the below diagram. You can refer to the explanation given below:

Git is a Distributed Version Control system (DVCS). It can track changes to a file and allows you to revert back to any particular change.
Its distributed architecture provides many advantages over other Version Control Systems (VCS) like SVN one major advantage is that it does not rely on a central server to store all the versions of a project’s files. Instead, every developer “clones” a copy of a repository I have shown in the diagram below with “Local repository” and has the full history of the project on his hard drive so that when there is a server outage, all you need for recovery is one of your teammate’s local Git repository.
There is a central cloud repository as well where developers can commit changes and share it with other teammates as you can see in the diagram where all collaborators are commiting changes “Remote repository”.

DevOps Interview Questions

Q6. Explain some basic Git commands?

Below are some basic Git commands:

DevOps Interview Questions

Q7. In Git how do you revert a commit that has already been pushed and made public?

There can be two answers to this question so make sure that you include both because any of the below options can be used depending on the situation:

Remove or fix the bad file in a new commit and push it to the remote repository. This is the most natural way to fix an error. Once you have made necessary changes to the file, commit it to the remote repository for that I will use
git commit -m “commit message”
Create a new commit that undoes all changes that were made in the bad commit.to do this I will use a command
git revert <name of bad commit>

Q8. How do you squash last N commits into a single commit?

There are two options to squash last N commits into a single commit. Include both of the below mentioned options in your answer:

If you want to write the new commit message from scratch use the following command
git reset –soft HEAD~N &&
git commit
If you want to start editing the new commit message with a concatenation of the existing commit messages then you need to extract those messages and pass them to Git commit for that I will use
git reset –soft HEAD~N &&
git commit –edit -m”$(git log –format=%B –reverse .HEAD@{N})”

Q9. What is Git bisect? How can you use it to determine the source of a (regression) bug?

I will suggest you to first give a small definition of Git bisect, Git bisect is used to find the commit that introduced a bug by using binary search. Command for Git bisect is
git bisect <subcommand> <options>
Now since you have mentioned the command above, explain what this command will do, This command uses a binary search algorithm to find which commit in your project’s history introduced a bug. You use it by first telling it a “bad” commit that is known to contain the bug, and a “good” commit that is known to be before the bug was introduced. Then Git bisect picks a commit between those two endpoints and asks you whether the selected commit is “good” or “bad”. It continues narrowing down the range until it finds the exact commit that introduced the change.

Q10. What is Git rebase and how can it be used to resolve conflicts in a feature branch before merge?

According to me, you should start by saying git rebase is a command which will merge another branch into the branch where you are currently working, and move all of the local commits that are ahead of the rebased branch to the top of the history on that branch.
Now once you have defined Git rebase time for an example to show how it can be used to resolve conflicts in a feature branch before merge, if a feature branch was created from master, and since then the master branch has received new commits, Git rebase can be used to move the feature branch to the tip of master.
The command effectively will replay the changes made in the feature branch at the tip of master, allowing conflicts to be resolved in the process. When done with care, this will allow the feature branch to be merged into master with relative ease and sometimes as a simple fast-forward operation.

Q11. How do you configure a Git repository to run code sanity checking tools right before making commits, and preventing them if the test fails?

I will suggest you to first give a small introduction to sanity checking, A sanity or smoke test determines whether it is possible and reasonable to continue testing.
Now explain how to achieve this, this can be done with a simple script related to the pre-commit hook of the repository. The pre-commit hook is triggered right before a commit is made, even before you are required to enter a commit message. In this script one can run other tools, such as linters and perform sanity checks on the changes being committed into the repository.
Finally give an example, you can refer the below script:

#!/bin/sh
files=$(git diff –cached –name-only –diff-filter=ACM | grep ‘.go$’)
if [ -z files ]; then
exit 0
fi
unfmtd=$(gofmt -l $files)
if [ -z unfmtd ]; then
exit 0
fi
echo “Some .go files are not fmt’d”
exit 1

This script checks to see if any .go file that is about to be committed needs to be passed through the standard Go source code formatting tool gofmt. By exiting with a non-zero status, the script effectively prevents the commit from being applied to the repository.

Q12. How do you find a list of files that has changed in a particular commit?

For this answer instead of just telling the command, explain what exactly this command will do so you can say that, To get a list files that has changed in a particular commit use command
git diff-tree -r {hash}
Given the commit hash, this will list all the files that were changed or added in that commit. The -r flag makes the command list individual files, rather than collapsing them into root directory names only.
You can also include the below mention point although it is totally optional but will help in impressing the interviewer.
The output will also include some extra information, which can be easily suppressed by including two flags:
git diff-tree –no-commit-id –name-only -r {hash}
Here –no-commit-id will suppress the commit hashes from appearing in the output, and –name-only will only print the file names, instead of their paths.

Q13. How do you setup a script to run every time a repository receives new commits through push?

There are three ways to configure a script to run every time a repository receives new commits through push, one needs to define either a pre-receive, update, or a post-receive hook depending on when exactly the script needs to be triggered.

Pre-receive hook in the destination repository is invoked when commits are pushed to it. Any script bound to this hook will be executed before any references are updated. This is a useful hook to run scripts that help enforce development policies.
Update hook works in a similar manner to pre-receive hook, and is also triggered before any updates are actually made. However, the update hook is called once for every commit that has been pushed to the destination repository.
Finally, post-receive hook in the repository is invoked after the updates have been accepted into the destination repository. This is an ideal place to configure simple deployment scripts, invoke some continuous integration systems, dispatch notification emails to repository maintainers, etc.

Hooks are local to every Git repository and are not versioned. Scripts can either be created within the hooks directory inside the “.git” directory, or they can be created elsewhere and links to those scripts can be placed within the directory.

Q14. How will you know in Git if a branch has already been merged into master?

I will suggest you to include both the below mentioned commands:
git branch –merged lists the branches that have been merged into the current branch.
git branch –no-merged lists the branches that have not been merged.

Continuous Integration questions

Now, let’s look at Continuous Integration interview questions:

Q1. What is meant by Continuous Integration?

I will advise you to begin this answer by giving a small definition of Continuous Integration (CI). It is a development practice that requires developers to integrate code into a shared repository several times a day. Each check-in is then verified by an automated build, allowing teams to detect problems early.
I suggest that you explain how you have implemented it in your previous job. You can refer the below given example:

DevOps Interview Questions

In the diagram shown above:

Developers check out code into their private workspaces.
When they are done with it they commit the changes to the shared repository (Version Control Repository).
The CI server monitors the repository and checks out changes when they occur.
The CI server then pulls these changes and builds the system and also runs unit and integration tests.
The CI server will now inform the team of the successful build.
If the build or tests fails, the CI server will alert the team.
The team will try to fix the issue at the earliest opportunity.
This process keeps on repeating.

Q2. Why do you need a Continuous Integration of Dev & Testing?

For this answer, you should focus on the need of Continuous Integration. My suggestion would be to mention the below explanation in your answer:
Continuous Integration of Dev and Testing improves the quality of software, and reduces the time taken to deliver it, by replacing the traditional practice of testing after completing all development. It allows Dev team to easily detect and locate problems early because developers need to integrate code into a shared repository several times a day (more frequently). Each check-in is then automatically tested.

Q3. What are the success factors for Continuous Integration?

Here you have to mention the requirements for Continuous Integration. You could include the following points in your answer:

Maintain a code repository
Automate the build
Make the build self-testing
Everyone commits to the baseline every day
Every commit (to baseline) should be built
Keep the build fast
Test in a clone of the production environment
Make it easy to get the latest deliverables
Everyone can see the results of the latest build
Automate deployment

Q4. Explain how you can move or copy Jenkins from one server to another?

I will approach this task by copying the jobs directory from the old server to the new one. There are multiple ways to do that; I have mentioned them below:
You can:

Move a job from one installation of Jenkins to another by simply copying the corresponding job directory.
Make a copy of an existing job by making a clone of a job directory by a different name.
Rename an existing job by renaming a directory. Note that if you change a job name you will need to change any other job that tries to call the renamed job.

Q5. Explain how can create a backup and copy files in Jenkins?

Answer to this question is really direct. To create a backup, all you need to do is to periodically back up your JENKINS_HOME directory. This contains all of your build jobs configurations, your slave node configurations, and your build history. To create a back-up of your Jenkins setup, just copy this directory. You can also copy a job directory to clone or replicate a job or rename the directory.

Q6. Explain how you can setup Jenkins job?

My approach to this answer will be to first mention how to create Jenkins job. Go to Jenkins top page, select “New Job”, then choose “Build a free-style software project”.
Then you can tell the elements of this freestyle job:

Optional SCM, such as CVS or Subversion where your source code resides.
Optional triggers to control when Jenkins will perform builds.
Some sort of build script that performs the build (ant, maven, shell script, batch file, etc.) where the real work happens.
Optional steps to collect information out of the build, such as archiving the artifacts and/or recording javadoc and test results.
Optional steps to notify other people/systems with the build result, such as sending e-mails, IMs, updating issue tracker, etc…

Q7. Mention some of the useful plugins in Jenkins.

Below, I have mentioned some important Plugins:

Maven 2 project
Amazon EC2
HTML publisher
Copy artifact
Join
Green Balls

These Plugins, I feel are the most useful plugins. If you want to include any other Plugin that is not mentioned above, you can add them as well. But, make sure you first mention the above stated plugins and then add your own.

Q8. How will you secure Jenkins?

The way I secure Jenkins is mentioned below. If you have any other way of doing it, please mention it in the comments section below:

Ensure global security is on.
Ensure that Jenkins is integrated with my company’s user directory with appropriate plugin.
Ensure that matrix/Project matrix is enabled to fine tune access.
Automate the process of setting rights/privileges in Jenkins with custom version controlled script.
Limit physical access to Jenkins data/folders.
Periodically run security audits on same.

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Continuous Testing Interview Questions:

Now let’s move on to the Continuous Testing questions.

Q1. What is Continuous Testing?

I will advise you to follow the below mentioned explanation:
Continuous Testing is the process of executing automated tests as part of the software delivery pipeline to obtain immediate feedback on the business risks associated with in the latest build. In this way, each build is tested continuously, allowing Development teams to get fast feedback so that they can prevent those problems from progressing to the next stage of Software delivery life-cycle. This dramatically speeds up a developer’s workflow as there’s no need to manually rebuild the project and re-run all tests after making changes.

Q2. What is Automation Testing?

Automation testing or Test Automation is a process of automating the manual process to test the application/system under test. Automation testing involves use of separate testing tools which lets you create test scripts which can be executed repeatedly and doesn’t require any manual intervention.
Q3. What are the benefits of Automation Testing?

I have listed down some advantages of automation testing. Include these in your answer and you can add your own experience of how Continuous Testing helped your previous company:

Supports execution of repeated test cases
Aids in testing a large test matrix
Enables parallel execution
Encourages unattended execution
Improves accuracy thereby reducing human generated errors
Saves time and money

Q4. How to automate Testing in DevOps lifecycle?

I have mentioned a generic flow below which you can refer to:
In DevOps, developers are required to commit all the changes made in the source code to a shared repository. Continuous Integration tools like Jenkins will pull the code from this shared repository every time a change is made in the code and deploy it for Continuous Testing that is done by tools like Selenium as shown in the below diagram.
In this way, any change in the code is continuously tested unlike the traditional approach.

DevOps Interview Questions

Q5. Why is Continuous Testing important for DevOps?

You can answer this question by saying, “Continuous Testing allows any change made in the code to be tested immediately. This avoids the problems created by having “big-bang” testing left to the end of the cycle such as release delays and quality issues. In this way, Continuous Testing facilitates more frequent and good quality releases.”

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Q6. What are the key elements of Continuous Testing tools?

Key elements of Continuous Testing are:

Risk Assessment: It Covers risk mitigation tasks, technical debt, quality assessment and test coverage optimization to ensure the build is ready to progress toward next stage.
Policy Analysis: It ensures all processes align with the organization’s evolving business and compliance demands are met.
Requirements Traceability: It ensures true requirements are met and rework is not required. An object assessment is used to identify which requirements are at risk, working as expected or require further validation.
Advanced Analysis: It uses automation in areas such as static code analysis, change impact analysis and scope assessment/prioritization to prevent defects in the first place and accomplishing more within each iteration.
Test Optimization: It ensures tests yield accurate outcomes and provide actionable findings. Aspects include Test Data Management, Test Optimization Management and Test Maintenance
Service Virtualization: It ensures access to real-world testing environments. Service visualization enables access to the virtual form of the required testing stages, cutting the waste time to test environment setup and availability.

Q7. Which Testing tool are you comfortable with and what are the benefits of that tool?

Here mention the testing tool that you have worked with and accordingly frame your answer. I have mentioned an example below:
I have worked on Selenium to ensure high quality and more frequent releases.

Some advantages of Selenium are:

It is free and open source
It has a large user base and helping communities
It has cross Browser compatibility (Firefox, chrome, Internet Explorer, Safari etc.)
It has great platform compatibility (Windows, Mac OS, Linux etc.)
It supports multiple programming languages (Java, C#, Ruby, Python, Pearl etc.)
It has fresh and regular repository developments
It supports distributed testing

Q8. What are the Testing types supported by Selenium?

Selenium supports two types of testing:
Regression Testing: It is the act of retesting a product around an area where a bug was fixed.
Functional Testing: It refers to the testing of software features (functional points) individually.

Q9. What is Selenium IDE?

My suggestion is to start this answer by defining Selenium IDE. It is an integrated development environment for Selenium scripts. It is implemented as a Firefox extension, and allows you to record, edit, and debug tests. Selenium IDE includes the entire Selenium Core, allowing you to easily and quickly record and play back tests in the actual environment that they will run in.
Now include some advantages in your answer. With autocomplete support and the ability to move commands around quickly, Selenium IDE is the ideal environment for creating Selenium tests no matter what style of tests you prefer.

Q10. What is the difference between Assert and Verify commands in Selenium?

I have mentioned differences between Assert and Verify commands below:

Assert command checks whether the given condition is true or false. Let’s say we assert whether the given element is present on the web page or not. If the condition is true, then the program control will execute the next test step. But, if the condition is false, the execution would stop and no further test would be executed.
Verify command also checks whether the given condition is true or false. Irrespective of the condition being true or false, the program execution doesn’t halts i.e. any failure during verification would not stop the execution and all the test steps would be executed.

Q11. How to launch Browser using WebDriver?

The following syntax can be used to launch Browser:
WebDriver driver = new FirefoxDriver();
WebDriver driver = new ChromeDriver();
WebDriver driver = new InternetExplorerDriver();

Q12. When should I use Selenium Grid?

For this answer, my suggestion would be to give a small definition of Selenium Grid. It can be used to execute same or different test scripts on multiple platforms and browsers concurrently to achieve distributed test execution. This allows testing under different environments and saving execution time remarkably.

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Configuration Management Interview Questions

Now let’s check how much you know about Configuration Management.

Q1. What are the goals of Configuration management processes?

The purpose of Configuration Management (CM) is to ensure the integrity of a product or system throughout its life-cycle by making the development or deployment process controllable and repeatable, therefore creating a higher quality product or system. The CM process allows orderly management of system information and system changes for purposes such as to:

Revise capability,
Improve performance,
Reliability or maintainability,
Extend life,
Reduce cost,
Reduce risk and
Liability, or correct defects.

Q2. What is the difference between Asset management and Configuration Management?

Given below are few differences between Asset Management and Configuration Management:

DevOps Interview Questions

Q3. What is the difference between an Asset and a Configuration Item?

According to me, you should first explain Asset. It has a financial value along with a depreciation rate attached to it. IT assets are just a sub-set of it. Anything and everything that has a cost and the organization uses it for its asset value calculation and related benefits in tax calculation falls under Asset Management, and such item is called an asset.
Configuration Item on the other hand may or may not have financial values assigned to it. It will not have any depreciation linked to it. Thus, its life would not be dependent on its financial value but will depend on the time till that item becomes obsolete for the organization.

Now you can give an example that can showcase the similarity and differences between both:

Similarity:
Server – It is both an asset as well as a CI.
Difference:
Building – It is an asset but not a CI.
Document – It is a CI but not an asset

Q4. What do you understand by “Infrastructure as code”? How does it fit into the DevOps methodology? What purpose does it achieve?

Infrastructure as Code (IAC) is a type of IT infrastructure that operations teams can use to automatically manage and provision through code, rather than using a manual process.
Companies for faster deployments treat infrastructure like software: as code that can be managed with the DevOps tools and processes. These tools let you make infrastructure changes more easily, rapidly, safely and reliably.

Q5. Which among Puppet, Chef, SaltStack and Ansible is the best Configuration Management (CM) tool? Why?

This depends on the organization’s need so mention few points on all those tools:
Puppet is the oldest and most mature CM tool. Puppet is a Ruby-based Configuration Management tool, but while it has some free features, much of what makes Puppet great is only available in the paid version. Organizations that don’t need a lot of extras will find Puppet useful, but those needing more customization will probably need to upgrade to the paid version.
Chef is written in Ruby, so it can be customized by those who know the language. It also includes free features, plus it can be upgraded from open source to enterprise-level if necessary. On top of that, it’s a very flexible product.
Ansible is a very secure option since it uses Secure Shell. It’s a simple tool to use, but it does offer a number of other services in addition to configuration management. It’s very easy to learn, so it’s perfect for those who don’t have a dedicated IT staff but still need a configuration management tool.
SaltStack is python based open source CM tool made for larger businesses, but its learning curve is fairly low.

Q6. What is Puppet?

I will advise you to first give a small definition of Puppet. It is a Configuration Management tool which is used to automate administration tasks.
Now you should describe its architecture and how Puppet manages its Agents. Puppet has a Master-Slave architecture in which the Slave has to first send a Certificate signing request to Master and Master has to sign that Certificate in order to establish a secure connection between Puppet Master and Puppet Slave as shown on the diagram below. Puppet Slave sends request to Puppet Master and Puppet Master then pushes configuration on Slave.
Refer the diagram below that explains the above description.

DevOps Interview Questions

Q7. Before a client can authenticate with the Puppet Master, its certs need to be signed and accepted. How will you automate this task?

The easiest way is to enable auto-signing in puppet.conf.
Do mention that this is a security risk. If you still want to do this:

Firewall your puppet master – restrict port tcp/8140 to only networks that you trust.
Create puppet masters for each ‘trust zone’, and only include the trusted nodes in that Puppet masters manifest.
Never use a full wildcard such as *.

Q8. Describe the most significant gain you made from automating a process through Puppet.

For this answer, I will suggest you to explain you past experience with Puppet. you can refer the below example:
I automated the configuration and deployment of Linux and Windows machines using Puppet. In addition to shortening the processing time from one week to 10 minutes, I used the roles and profiles pattern and documented the purpose of each module in README to ensure that others could update the module using Git. The modules I wrote are still being used, but they’ve been improved by my teammates and members of the community

Q9. Which open source or community tools do you use to make Puppet more powerful?

Over here, you need to mention the tools and how you have used those tools to make Puppet more powerful. Below is one example for your reference:
Changes and requests are ticketed through Jira and we manage requests through an internal process. Then, we use Git and Puppet’s Code Manager app to manage Puppet code in accordance with best practices. Additionally, we run all of our Puppet changes through our continuous integration pipeline in Jenkins using the beaker testing framework.

Q10. What are Puppet Manifests?

It is a very important question so make sure you go in a correct flow. According to me, you should first define Manifests. Every node (or Puppet Agent) has got its configuration details in Puppet Master, written in the native Puppet language. These details are written in the language which Puppet can understand and are termed as Manifests. They are composed of Puppet code and their filenames use the .pp extension.
Now give an exampl. You can write a manifest in Puppet Master that creates a file and installs apache on all Puppet Agents (Slaves) connected to the Puppet Master.

Q11. What is Puppet Module and How it is different from Puppet Manifest?

For this answer, you can go with the below mentioned explanation:
A Puppet Module is a collection of Manifests and data (such as facts, files, and templates), and they have a specific directory structure. Modules are useful for organizing your Puppet code, because they allow you to split your code into multiple Manifests. It is considered best practice to use Modules to organize almost all of your Puppet Manifests.
Puppet programs are called Manifests which are composed of Puppet code and their file names use the .pp extension.

Q12. What is Facter in Puppet?

You are expected to answer what exactly Facter does in Puppet so according to me, you should say, “Facter gathers basic information (facts) about Puppet Agent such as hardware details, network settings, OS type and version, IP addresses, MAC addresses, SSH keys, and more. These facts are then made available in Puppet Master’s Manifests as variables.”

Q13. What is Chef?

Begin this answer by defining Chef. It is a powerful automation platform that transforms infrastructure into code. Chef is a tool for which you write scripts that are used to automate processes. What processes? Pretty much anything related to IT.
Now you can explain the architecture of Chef, it consists of:

Chef Server: The Chef Server is the central store of your infrastructure’s configuration data. The Chef Server stores the data necessary to configure your nodes and provides search, a powerful tool that allows you to dynamically drive node configuration based on data.
Chef Node: A Node is any host that is configured using Chef-client. Chef-client runs on your nodes, contacting the Chef Server for the information necessary to configure the node. Since a Node is a machine that runs the Chef-client software, nodes are sometimes referred to as “clients”.
Chef Workstation: A Chef Workstation is the host you use to modify your cookbooks and other configuration data.

Q14. What is a resource in Chef?

My suggestion is to first define Resource. A Resource represents a piece of infrastructure and its desired state, such as a package that should be installed, a service that should be running, or a file that should be generated.
You should explain about the functions of Resource for that include the following points:

Describes the desired state for a configuration item.
Declares the steps needed to bring that item to the desired state.
Specifies a resource type such as package, template, or service.
Lists additional details (also known as resource properties), as necessary.
Are grouped into recipes, which describe working configurations.

Q15. What do you mean by recipe in Chef?

For this answer, I will suggest you to use the above mentioned flow: first define Recipe. A Recipe is a collection of Resources that describes a particular configuration or policy. A Recipe describes everything that is required to configure part of a system.
After the definition, explain the functions of Recipes by including the following points:

Install and configure software components.
Manage files.
Deploy applications.
Execute other recipes.

Q16. How does a Cookbook differ from a Recipe in Chef?

The answer to this is pretty direct. You can simply say, “a Recipe is a collection of Resources, and primarily configures a software package or some piece of infrastructure. A Cookbook groups together Recipes and other information in a way that is more manageable than having just Recipes alone.”

Q17. What happens when you don’t specify a Resource’s action in Chef?

My suggestion is to first give a direct answer: when you don’t specify a resource’s action, Chef applies the default action.
Now explain this with an example, the below resource:
file ‘C:UsersAdministratorchef-reposettings.ini’ do
content ‘greeting=hello world’
end
is same as the below resource:
file ‘C:UsersAdministratorchef-reposettings.ini’ do
action :create
content ‘greeting=hello world’
end
because: create is the file Resource’s default action.

Q18. What is Ansible module?

Modules are considered to be the units of work in Ansible. Each module is mostly standalone and can be written in a standard scripting language such as Python, Perl, Ruby, bash, etc… One of the guiding properties of modules is idempotency, which means that even if an operation is repeated multiple times e.g. upon recovery from an outage, it will always place the system into the same state.

Q19. What are playbooks in Ansible?

Playbooks are Ansible’s configuration, deployment, and orchestration language. They can describe a policy you want your remote systems to enforce, or a set of steps in a general IT process. Playbooks are designed to be human-readable and are developed in a basic text language.
At a basic level, playbooks can be used to manage configurations of and deployments to remote machines.

Q20. How do I see a list of all of the ansible_ variables?

Ansible by default gathers “facts” about the machines under management, and these facts can be accessed in Playbooks and in templates. To see a list of all of the facts that are available about a machine, you can run the “setup” module as an ad-hoc action:
Ansible -m setup hostname
This will print out a dictionary of all of the facts that are available for that particular host.

Q21. How can I set deployment order for applications?

WebLogic Server 8.1 allows you to select the load order for applications. See the Application MBean Load Order attribute in Application. WebLogic Server deploys server-level resources (first JDBC and then JMS) before deploying applications. Applications are deployed in this order: connectors, then EJBs, then Web Applications. If the application is an EAR, the individual components are loaded in the order in which they are declared in the application.xml deployment descriptor.

Q22. Can I refresh static components of a deployed application without having to redeploy the entire application?

Yes, you can use weblogic.Deployer to specify a component and target a server, using the following syntax:
java weblogic.Deployer -adminurl http://admin:7001 -name appname -targets server1,server2 -deploy jsps/*.jsp

Q23. How do I turn the auto-deployment feature off?

The auto-deployment feature checks the applications folder every three seconds to determine whether there are any new applications or any changes to existing applications and then dynamically deploys these changes.

The auto-deployment feature is enabled for servers that run in development mode. To disable auto-deployment feature, use one of the following methods to place servers in production mode:

In the Administration Console, click the name of the domain in the left pane, then select the Production Mode checkbox in the right pane.
At the command line, include the following argument when starting the domain’s Administration Server:
-Dweblogic.ProductionModeEnabled=true
Production mode is set for all WebLogic Server instances in a given domain.

Q24. When should I use the external_stage option?

Set -external_stage using weblogic.Deployer if you want to stage the application yourself, and prefer to copy it to its target by your own means.

Ansible and Puppet are two of the most popular configuration management tools among DevOps engineers.

Continuous Monitoring Interview Questions

Let’s test your knowledge on Continuous Monitoring.

Q1. Why is Continuous monitoring necessary?

I will suggest you to go with the below mentioned flow:
Continuous Monitoring allows timely identification of problems or weaknesses and quick corrective action that helps reduce expenses of an organization. Continuous monitoring provides solution that addresses three operational disciplines known as:

continuous audit
continuous controls monitoring
continuous transaction inspection

Q2. What is Nagios?

You can answer this question by first mentioning that Nagios is one of the monitoring tools. It is used for Continuous monitoring of systems, applications, services, and business processes etc in a DevOps culture. In the event of a failure, Nagios can alert technical staff of the problem, allowing them to begin remediation processes before outages affect business processes, end-users, or customers. With Nagios, you don’t have to explain why an unseen infrastructure outage affect your organization’s bottom line.
Now once you have defined what is Nagios, you can mention the various things that you can achieve using Nagios.
By using Nagios you can:

Plan for infrastructure upgrades before outdated systems cause failures.
Respond to issues at the first sign of a problem.
Automatically fix problems when they are detected.
Coordinate technical team responses.
Ensure your organization’s SLAs are being met.
Ensure IT infrastructure outages have a minimal effect on your organization’s bottom line.
Monitor your entire infrastructure and business processes.

This completes the answer to this question. Further details like advantages etc. can be added as per the direction where the discussion is headed.

Q3. How does Nagios works?

I will advise you to follow the below explanation for this answer:
Nagios runs on a server, usually as a daemon or service. Nagios periodically runs plugins residing on the same server, they contact hosts or servers on your network or on the internet. One can view the status information using the web interface. You can also receive email or SMS notifications if something happens.
The Nagios daemon behaves like a scheduler that runs certain scripts at certain moments. It stores the results of those scripts and will run other scripts if these results change.

Now expect a few questions on Nagios components like Plugins, NRPE etc…

Q4. What are Plugins in Nagios?

Begin this answer by defining Plugins. They are scripts (Perl scripts, Shell scripts, etc.) that can run from a command line to check the status of a host or service. Nagios uses the results from Plugins to determine the current status of hosts and services on your network.
Once you have defined Plugins, explain why we need Plugins. Nagios will execute a Plugin whenever there is a need to check the status of a host or service. Plugin will perform the check and then simply returns the result to Nagios. Nagios will process the results that it receives from the Plugin and take the necessary actions.

Q5. What is NRPE (Nagios Remote Plugin Executor) in Nagios?

For this answer, give a brief definition of Plugins. The NRPE addon is designed to allow you to execute Nagios plugins on remote Linux/Unix machines. The main reason for doing this is to allow Nagios to monitor “local” resources (like CPU load, memory usage, etc.) on remote machines. Since these public resources are not usually exposed to external machines, an agent like NRPE must be installed on the remote Linux/Unix machines.

I will advise you to explain the NRPE architecture on the basis of diagram shown below. The NRPE addon consists of two pieces:

The check_nrpe plugin, which resides on the local monitoring machine.
The NRPE daemon, which runs on the remote Linux/Unix machine.

There is a SSL (Secure Socket Layer) connection between monitoring host and remote host as shown in the diagram below.

DevOps Interview Questions

Q6. What do you mean by passive check in Nagios?

According to me, the answer should start by explaining Passive checks. They are initiated and performed by external applications/processes and the Passive check results are submitted to Nagios for processing.
Then explain the need for passive checks. They are useful for monitoring services that are Asynchronous in nature and cannot be monitored effectively by polling their status on a regularly scheduled basis. They can also be used for monitoring services that are Located behind a firewall and cannot be checked actively from the monitoring host.

Q7. When Does Nagios Check for external commands?

Make sure that you stick to the question during your explanation so I will advise you to follow the below mentioned flow. Nagios check for external commands under the following conditions:

At regular intervals specified by the command_check_interval option in the main configuration file or,
Immediately after event handlers are executed. This is in addition to the regular cycle of external command checks and is done to provide immediate action if an event handler submits commands to Nagios.

Q8. What is the difference between Active and Passive check in Nagios?

For this answer, first point out the basic difference Active and Passive checks. The major difference between Active and Passive checks is that Active checks are initiated and performed by Nagios, while passive checks are performed by external applications.
If your interviewer is looking unconvinced with the above explanation then you can also mention some key features of both Active and Passive checks:
Passive checks are useful for monitoring services that are:

Asynchronous in nature and cannot be monitored effectively by polling their status on a regularly scheduled basis.
Located behind a firewall and cannot be checked actively from the monitoring host.

The main features of Actives checks are as follows:

Active checks are initiated by the Nagios process.
Active checks are run on a regularly scheduled basis.

Q9. How does Nagios help with Distributed Monitoring?

The interviewer will be expecting an answer related to the distributed architecture of Nagios. So, I suggest that you answer it in the below mentioned format:
With Nagios you can monitor your whole enterprise by using a distributed monitoring scheme in which local slave instances of Nagios perform monitoring tasks and report the results back to a single master. You manage all configuration, notification, and reporting from the master, while the slaves do all the work. This design takes advantage of Nagios’s ability to utilize passive checks i.e. external applications or processes that send results back to Nagios. In a distributed configuration, these external applications are other instances of Nagios.

Q10. Explain Main Configuration file of Nagios and its location?

First mention what this main configuration file contains and its function. The main configuration file contains a number of directives that affect how the Nagios daemon operates. This config file is read by both the Nagios daemon and the CGIs (It specifies the location of your main configuration file).
Now you can tell where it is present and how it is created. A sample main configuration file is created in the base directory of the Nagios distribution when you run the configure script. The default name of the main configuration file is nagios.cfg. It is usually placed in the etc/ subdirectory of you Nagios installation (i.e. /usr/local/nagios/etc/).

Q11. Explain how Flap Detection works in Nagios?

I will advise you to first explain Flapping first. Flapping occurs when a service or host changes state too frequently, this causes lot of problem and recovery notifications.
Once you have defined Flapping, explain how Nagios detects Flapping. Whenever Nagios checks the status of a host or service, it will check to see if it has started or stopped flapping. Nagios follows the below given procedure to do that:

Storing the results of the last 21 checks of the host or service analyzing the historical check results and determine where state changes/transitions occur
Using the state transitions to determine a percent state change value (a measure of change) for the host or service
Comparing the percent state change value against low and high flapping thresholds

A host or service is determined to have started flapping when its percent state change first exceeds a high flapping threshold. A host or service is determined to have stopped flapping when its percent state goes below a low flapping threshold.

Q12. What are the three main variables that affect recursion and inheritance in Nagios?

According to me the proper format for this answer should be:
First name the variables and then a small explanation of each of these variables:

Name
Use
Register

Then give a brief explanation for each of these variables. Name is a placeholder that is used by other objects. Use defines the “parent” object whose properties should be used. Register can have a value of 0 (indicating its only a template) and 1 (an actual object). The register value is never inherited.

Q13. What is meant by saying Nagios is Object Oriented?

Answer to this question is pretty direct. I will answer this by saying, “One of the features of Nagios is object configuration format in that you can create object definitions that inherit properties from other object definitions and hence the name. This simplifies and clarifies relationships between various components.”

Q14. What is State Stalking in Nagios?

I will advise you to first give a small introduction on State Stalking. It is used for logging purposes. When Stalking is enabled for a particular host or service, Nagios will watch that host or service very carefully and log any changes it sees in the output of check results.
Depending on the discussion between you and interviewer you can also add, “It can be very helpful in later analysis of the log files. Under normal circumstances, the result of a host or service check is only logged if the host or service has changed state since it was last checked.”

Containerization and Virtualization Interview Questions

Let’s see how much you know about containers and VMs.

Q1. What are containers?

My suggestion is to explain the need for containerization first, containers are used to provide consistent computing environment from a developer’s laptop to a test environment, from a staging environment into production.
Now give a definition of containers, a container consists of an entire runtime environment: an application, plus all its dependencies, libraries and other binaries, and configuration files needed to run it, bundled into one package. Containerizing the application platform and its dependencies removes the differences in OS distributions and underlying infrastructure.
DevOps Interview Questions

Q2. What are the advantages that Containerization provides over virtualization?

Below are the advantages of containerization over virtualization:

Containers provide real-time provisioning and scalability but VMs provide slow provisioning
Containers are lightweight when compared to VMs
VMs have limited performance when compared to containers
Containers have better resource utilization compared to VMs

Q3. How exactly are containers (Docker in our case) different from hypervisor virtualization (vSphere)? What are the benefits?

Given below are some differences. Make sure you include these differences in your answer:
DevOps Interview Questions

Q4. What is Docker image?

I suggest that you go with the below mentioned flow:
Docker image is the source of Docker container. In other words, Docker images are used to create containers. Images are created with the build command, and they’ll produce a container when started with run. Images are stored in a Docker registry such as registry.hub.docker.com because they can become quite large, images are designed to be composed of layers of other images, allowing a minimal amount of data to be sent when transferring images over the network.

Q5. What is Docker container?

This is a very important question so just make sure you don’t deviate from the topic. I advise you to follow the below mentioned format:
Docker containers include the application and all of its dependencies but share the kernel with other containers, running as isolated processes in user space on the host operating system. Docker containers are not tied to any specific infrastructure: they run on any computer, on any infrastructure, and in any cloud.
Now explain how to create a Docker container, Docker containers can be created by either creating a Docker image and then running it or you can use Docker images that are present on the Dockerhub.
Docker containers are basically runtime instances of Docker images.

Q6. What is Docker hub?

Answer to this question is pretty direct. Docker hub is a cloud-based registry service which allows you to link to code repositories, build your images and test them, stores manually pushed images, and links to Docker cloud so you can deploy images to your hosts. It provides a centralized resource for container image discovery, distribution and change management, user and team collaboration, and workflow automation throughout the development pipeline.

Q7. How is Docker different from other container technologies?

According to me, below points should be there in your answer:
Docker containers are easy to deploy in a cloud. It can get more applications running on the same hardware than other technologies, it makes it easy for developers to quickly create, ready-to-run containerized applications and it makes managing and deploying applications much easier. You can even share containers with your applications.
If you have some more points to add you can do that but make sure the above the above explanation is there in your answer.

Q8. What is Docker Swarm?

You should start this answer by explaining Docker Swarn. It is native clustering for Docker which turns a pool of Docker hosts into a single, virtual Docker host. Docker Swarm serves the standard Docker API, any tool that already communicates with a Docker daemon can use Swarm to transparently scale to multiple hosts.
I will also suggest you to include some supported tools:

Dokku
Docker Compose
Docker Machine
Jenkins

Q9. What is Dockerfile used for?

This answer according to me should begin by explaining the use of Dockerfile. Docker can build images automatically by reading the instructions from a Dockerfile.
Now I suggest you to give a small definition of Dockerfle. A Dockerfile is a text document that contains all the commands a user could call on the command line to assemble an image. Using docker build users can create an automated build that executes several command-line instructions in succession.

Now expect a few questions to test your experience with Docker.

Q10. Can I use json instead of yaml for my compose file in Docker?

You can use json instead of yaml for your compose file, to use json file with compose, specify the filename to use for eg:
docker-compose -f docker-compose.json up

Q11. Tell us how you have used Docker in your past position?

Explain how you have used Docker to help rapid deployment. Explain how you have scripted Docker and used Docker with other tools like Puppet, Chef or Jenkins. If you have no past practical experience in Docker and have past experience with other tools in similar space, be honest and explain the same. In this case, it makes sense if you can compare other tools to Docker in terms of functionality.

Q12. How to create Docker container?

I will suggest you to give a direct answer to this. We can use Docker image to create Docker container by using the below command:
docker run -t -i <image name> <command name>
This command will create and start container.
You should also add, If you want to check the list of all running container with status on a host use the below command:
docker ps -a

Q13. How to stop and restart the Docker container?

In order to stop the Docker container you can use the below command:
docker stop <container ID>
Now to restart the Docker container you can use:
docker restart <container ID>

Q14. How far do Docker containers scale?

Large web deployments like Google and Twitter, and platform providers such as Heroku and dotCloud all run on container technology, at a scale of hundreds of thousands or even millions of containers running in parallel.

Q15. What platforms does Docker run on?

I will start this answer by saying Docker runs on only Linux and Cloud platforms and then I will mention the below vendors of Linux:

Ubuntu 12.04, 13.04 et al
Fedora 19/20+
RHEL 6.5+
CentOS 6+
Gentoo
ArchLinux
openSUSE 12.3+
CRUX 3.0+

Cloud:

Amazon EC2
Google Compute Engine
Microsoft Azure
Rackspace

Note that Docker does not run on Windows or Mac.

Q16. Do I lose my data when the Docker container exits?

You can answer this by saying, no I won’t loose my data when Dcoker container exits. Any data that your application writes to disk gets preserved in its container until you explicitly delete the container. The file system for the container persists even after the container halts.

And, that’s it!

I hope these questions help you crack your DevOps interview. If you have any more questions for us, do mention them in the comments section and we will get back to you.

Originally published at https://www.edureka.co

#devops #docker #interview #kubernetes #interview-questions

Sigrid Farrell

1623718560

How to Extend your DevOps Strategy For Success in the Cloud?

DevOps and Cloud computing are joined at the hip, now that fact is well appreciated by the organizations that engaged in SaaS cloud and developed applications in the Cloud. During the COVID crisis period, most of the organizations have started using cloud computing services and implementing a cloud-first strategy to establish their remote operations. Similarly, the extended DevOps strategy will make the development process more agile with automated test cases.

According to the survey in EMEA, IT decision-makers have observed a 129%* improvement in the overall software development process when performing DevOps on the Cloud. This success result was just 81% when practicing only DevOps and 67%* when leveraging Cloud without DevOps. Not only that, but the practice has also made the software predictability better, improve the customer experience as well as speed up software delivery 2.6* times faster.

3 Core Principle to fit DevOps Strategy

If you consider implementing DevOps in concert with the Cloud, then the

below core principle will guide you to utilize the strategy.

It is indispensable to follow a continuous process, including all stages from Dev to deploy with the help of auto-provisioning resources of the target platform.
The team always keeps an eye on major and minor application changes that can typically appear within a few hours of development to operation. However, the support of unlimited resource provisioning is needed at the stage of deployment.
Cloud or hybrid configuration can associate this process, but you must confirm that configuration should support multiple cloud brands like Microsoft, AWS, Google, any public and private cloud models.

Guide to Remold Business with DevOps and Cloud

Companies are now re-inventing themselves to become better at sensing the next big thing their customers need and finding ways with the Cloud based DevOps to get ahead of the competition.

#devops #devops-principles #azure-devops #devops-transformation #good-company #devops-tools #devops-top-story #devops-infrastructure

Brain Crist

1594753020

Citrix Bugs Allow Unauthenticated Code Injection, Data Theft

Multiple vulnerabilities in the Citrix Application Delivery Controller (ADC) and Gateway would allow code injection, information disclosure and denial of service, the networking vendor announced Tuesday. Four of the bugs are exploitable by an unauthenticated, remote attacker.

The Citrix products (formerly known as NetScaler ADC and Gateway) are used for application-aware traffic management and secure remote access, respectively, and are installed in at least 80,000 companies in 158 countries, according to a December assessment from Positive Technologies.

Other flaws announced Tuesday also affect Citrix SD-WAN WANOP appliances, models 4000-WO, 4100-WO, 5000-WO and 5100-WO.

Attacks on the management interface of the products could result in system compromise by an unauthenticated user on the management network; or system compromise through cross-site scripting (XSS). Attackers could also create a download link for the device which, if downloaded and then executed by an unauthenticated user on the management network, could result in the compromise of a local computer.

“Customers who have configured their systems in accordance with Citrix recommendations [i.e., to have this interface separated from the network and protected by a firewall] have significantly reduced their risk from attacks to the management interface,” according to the vendor.

Threat actors could also mount attacks on Virtual IPs (VIPs). VIPs, among other things, are used to provide users with a unique IP address for communicating with network resources for applications that do not allow multiple connections or users from the same IP address.

The VIP attacks include denial of service against either the Gateway or Authentication virtual servers by an unauthenticated user; or remote port scanning of the internal network by an authenticated Citrix Gateway user.

“Attackers can only discern whether a TLS connection is possible with the port and cannot communicate further with the end devices,” according to the critical Citrix advisory. “Customers who have not enabled either the Gateway or Authentication virtual servers are not at risk from attacks that are applicable to those servers. Other virtual servers e.g. load balancing and content switching virtual servers are not affected by these issues.”

A final vulnerability has been found in Citrix Gateway Plug-in for Linux that would allow a local logged-on user of a Linux system with that plug-in installed to elevate their privileges to an administrator account on that computer, the company said.

#vulnerabilities #adc #citrix #code injection #critical advisory #cve-2020-8187 #cve-2020-8190 #cve-2020-8191 #cve-2020-8193 #cve-2020-8194 #cve-2020-8195 #cve-2020-8196 #cve-2020-8197 #cve-2020-8198 #cve-2020-8199 #denial of service #gateway #information disclosure #patches #security advisory #security bugs

Top 100 DevOps Interview Questions You Must Prepare in 2020

Top DevOps Interview Questions

Q1. What are the fundamental differences between DevOps & Agile?

Q2. What is the need for DevOps?

Q3. How is DevOps different from Agile / SDLC?

Q4. Which are the top DevOps tools? Which tools have you worked on?

Q5. How do all these tools work together?

Q6. What are the advantages of DevOps?

Q7. What is the most important thing DevOps helps us achieve?

Q8. Explain with a use case where DevOps can be used in industry/ real-life.

Q9. Explain your understanding and expertise on both the software development side and the technical operations side of an organization you have worked with in the past.

Q10. What are the anti-patterns of DevOps?

Version Control System (VCS) Interview Questions

Q1. What is Version control?

Q2. What are the benefits of using version control?

Q3. Describe branching strategies you have used.

Q4. Which VCS tool you are comfortable with?

Q5. What is Git?

Q6. Explain some basic Git commands?

Q7. In Git how do you revert a commit that has already been pushed and made public?

Q8. How do you squash last N commits into a single commit?

Q9. What is Git bisect? How can you use it to determine the source of a (regression) bug?

Q10. What is Git rebase and how can it be used to resolve conflicts in a feature branch before merge?

Q11. How do you configure a Git repository to run code sanity checking tools right before making commits, and preventing them if the test fails?

Q12. How do you find a list of files that has changed in a particular commit?

Q13. How do you setup a script to run every time a repository receives new commits through push?

Q14. How will you know in Git if a branch has already been merged into master?

Continuous Integration questions

Q1. What is meant by Continuous Integration?

Q2. Why do you need a Continuous Integration of Dev & Testing?

Q3. What are the success factors for Continuous Integration?

Q4. Explain how you can move or copy Jenkins from one server to another?

Q5. Explain how can create a backup and copy files in Jenkins?

Q6. Explain how you can setup Jenkins job?

Q7. Mention some of the useful plugins in Jenkins.

Q8. How will you secure Jenkins?

Continuous Testing Interview Questions:

Q1. What is Continuous Testing?

Q2. What is Automation Testing?

Q4. How to automate Testing in DevOps lifecycle?

Q5. Why is Continuous Testing important for DevOps?

Q6. What are the key elements of Continuous Testing tools?

Q7. Which Testing tool are you comfortable with and what are the benefits of that tool?

Q8. What are the Testing types supported by Selenium?

Q9. What is Selenium IDE?

Q10. What is the difference between Assert and Verify commands in Selenium?

Q11. How to launch Browser using WebDriver?

Q12. When should I use Selenium Grid?

Configuration Management Interview Questions

Q1. What are the goals of Configuration management processes?

Q2. What is the difference between Asset management and Configuration Management?

Q3. What is the difference between an Asset and a Configuration Item?

Q4. What do you understand by “Infrastructure as code”? How does it fit into the DevOps methodology? What purpose does it achieve?

Q5. Which among Puppet, Chef, SaltStack and Ansible is the best Configuration Management (CM) tool? Why?

Q6. What is Puppet?

Q7. Before a client can authenticate with the Puppet Master, its certs need to be signed and accepted. How will you automate this task?

Q8. Describe the most significant gain you made from automating a process through Puppet.

Q9. Which open source or community tools do you use to make Puppet more powerful?

Q10. What are Puppet Manifests?

Q11. What is Puppet Module and How it is different from Puppet Manifest?

Q12. What is Facter in Puppet?

Q13. What is Chef?

Q14. What is a resource in Chef?

Q15. What do you mean by recipe in Chef?

Q16. How does a Cookbook differ from a Recipe in Chef?

Q17. What happens when you don’t specify a Resource’s action in Chef?

Q18. What is Ansible module?

Q19. What are playbooks in Ansible?

Q20. How do I see a list of all of the ansible_ variables?

Q21. How can I set deployment order for applications?

Q22. Can I refresh static components of a deployed application without having to redeploy the entire application?

Q23. How do I turn the auto-deployment feature off?

Q24. When should I use the external_stage option?

Continuous Monitoring Interview Questions

Q1. Why is Continuous monitoring necessary?

Q2. What is Nagios?

Q3. How does Nagios works?

Q4. What are Plugins in Nagios?

Q5. What is NRPE (Nagios Remote Plugin Executor) in Nagios?

Q6. What do you mean by passive check in Nagios?