Work with a Custom VPC

Custom or nondefault VPCs are networks we create and administer based on our requirements. They are isolated networks that don’t permit inbound or outbound traffic, unless we set explicit network configurations according to our requirements.

Contrary to the default VPC, which is always created with the same network configuration, a custom VPC give us the choice to design a VPC with our own network configuration.

Determining VPC CIDR

The first question to be answered before creating a custom VPC is with what network CIDR Classless Inter-Domain Routing should the VPC be formed. To put it another way, how many IP addresses should our VPC have?

First, we need to determine the number of IP addresses that are required for our custom VPC network. As each resource will use an IP address, it is necessary to estimate how many resources, such as EC2 instances, RDS instances, etc., ...