Amazon VPC (Amazon Virtual Private Cloud) is used to launch AWS resources into a virtual network. The various components inside the Amazon VPC defines the traffic, security, routing configurations etc.
AWS Global Infrastructure at the high level were distributed as Regions. Region is a physical location in the world like Ireland, London, Singapore etc. Each region is further composed of Availability Zones (AZ). Availability Zones (AZ) are nothing but discrete data centers. For example, if Singapore is the region, then within that region, then AWS might have 3 different data centers located in the East, West, South of Singapore, that are isolated from one another. So if there is a power outage or accidental fire in one data center, the other data center will continue to operate without causing any disruption.
Having defined the regions and availability zones, the following diagram helps to fit VPC in the global infrastructure. Amazon VPC is the virtual network that span across multiple Availability Zones in a Region.
Amazon VPC — Overview
Amazon VPC is defined at the region level and it spans across multiple availability zones. So when instance has to be created inside the VPC, it can be chosen to host them in any of the availability zones inside the region. The instance is the physical server that has an IP address and are physically placed inside a data center (Availability Zone).
To visualize it, imagine placing your laptop (instance) in one of your office premises at location A(Availability Zone-a). You are visiting another branch at location B(Availability Zone — b) of your office on the next day and you have to resume your work. The instance you placed at location A cannot be physically accessible to you. But, if the data inside your laptop (instance) at location A can be copied to another laptop at location B, then you would be able to resume your work. You usually don’t care about the physical location as long as we were able to perform the same function as you did with the laptop (instance) at A.
The availability zones though might seem redundant, often most real world applications are hosted in more than one availability zones for the resiliency during the time of disruption. So when we define our virtual network (VPC), it has the option to span across multiple availability zones within the same region.
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