Recommendations and Limitations Flashcards
1
Q
VPC and subnet sizing for IPv4
A
When you create a VPC, you must specify an IPv4 CIDR block for the VPC. The allowed block size is between a /16 netmask (65,536 IP addresses) and /28 netmask (16 IP addresses). After you’ve created your VPC, you can associate secondary CIDR blocks with the VPC. For more information, see Manage IPv4 CIDR blocks for a VPC.
When you create a VPC, we recommend that you specify a CIDR block from the private IPv4 address ranges as specified in RFC 1918:
RFC 1918 range…………………………………….Example CIDR block
- 0.0.0 - 10.255.255.255 (10/8 prefix) Your VPC must be /16 or smaller, for example, 10.0.0.0/16.
- 16.0.0 - 172.31.255.255 (172.16/12 prefix) Your VPC must be /16 or smaller, for example, 172.31.0.0/16.
- 168.0.0 - 192.168.255.255 (192.168/16 prefix) Your VPC can be smaller, for example 192.168.0.0/20.
