secondaryCidrBlock

The IPv4 CIDR block. Take note of the following requirements:

• You can specify one of the following standard IPv4 CIDR blocks or their subnets as the secondary IPv4 CIDR block: 192.168.0.0/16, 172.16.0.0/12, and 10.0.0.0/8.

• You can also use a custom CIDR block other than 100.64.0.0/10, 224.0.0.0/4, 127.0.0.0/8, 169.254.0.0/16, or their subnets as the secondary IPv4 CIDR block of the VPC.

• The CIDR block cannot start with 0. The subnet mask must be 8 to 28 bits in length.

• The secondary CIDR block cannot overlap with the primary CIDR block or an existing secondary CIDR block.