The Amazon Virtual Private Cloud (Amazon VPC) is a custom-defined virtual network within the AWS Cloud. You can provision your own logically isolated section of AWS, similar to designing and implementing a separate independent network that would operate in an onpremises data center.
Within a region, you can create multiple Amazon VPCs, and each Amazon VPC is logically isolated even if it shares its IP address space. When you create an Amazon VPC, you must specify the IPv4 address range by choosing a Classless Inter-Domain Routing (CIDR) block, such as 10.0.0.0/16. The address range of the Amazon VPC cannot be changed after the Amazon VPC is created. An Amazon VPC address range may be as large as /16 (65,536 available addresses) or as small as /28 (16 available addresses) and should not overlap any other network with which they are to be connected.
The Amazon VPC service was released after the Amazon EC2 service and because of this, there are two different networking platforms available within AWS: EC2-Classic and EC2-VPC. Amazon EC2 originally launched with a single, flat network shared with other AWS customers called EC2-Classic. As such, AWS accounts created prior to the arrival of the Amazon VPC service can launch instances into the EC2-Classic network and EC2-VPC. AWS accounts created after December 2013 only support launching instances using EC2-VPC. AWS accounts that support EC2-VPC will have a default VPC created in each region with a default subnet created in each Availability Zone. The assigned CIDR block of the VPC will be 172.31.0.0/16.
An Amazon VPC consists of the following components:
Nameand the value that you specify.