Which CIDR Blocks Are Available for the VPC Service?

When creating a VPC, you need to specify an IPv4 CIDR block for it. Consider the following when selecting a CIDR block:

• Reserve enough IP addresses for subsequent service expansion.
• Avoid CIDR block conflicts. To enable communications between VPCs or between a VPC and an on-premises data center, ensure their CIDR blocks do not overlap.

Table 1 lists the supported VPC CIDR blocks.