What is the maximum size IP address range you can have in an Amazon VPC?

The maximum size IP address range you can have in an Amazon Virtual Private Cloud (VPC) is a /16 CIDR block. A /16 means that the first 16 bits of the IP address are fixed, and the remaining 16 bits can be used for host addresses within that VPC. This allocation allows for a total of 65,536 possible IP addresses (2^16), which provides a substantial range for private networking within your VPC.

Using a /16 CIDR block is particularly beneficial for organizations that anticipate needing many subnets or a large number of resources, as it gives them the flexibility to divide that address space into smaller subnets to organize and manage resources effectively.

In comparison, the other size options such as /8, /12, and /20 either represent smaller ranges than the /16 or do not meet the requirements for maximum size in a VPC. It's also important to note that while a /8 is larger than /16, it is not a valid choice for an Amazon VPC as it exceeds the maximum CIDR block size allowed. The /12 and /20 CIDR blocks provide fewer IP addresses than /16, making /16 the optimal selection for maximum addressable range in a VPC