Defining an IPv4 CIDR (Classless Inter-Domain Routing) notation.

yaml
VPC Name: MyVPC
IPv4 CIDR Block: 10.0.0.0/16

In this example, the CIDR block "10.0.0.0/16" indicates that the VPC will use IP addresses ranging from 10.0.0.0 to 10.0.255.255.

 

 

Subnet Name: PublicSubnet CIDR Block: 10.0.1.0/24 Availability Zone: us-east-1a

 

 

In example:

• VPC IPv4 CIDR Block: 10.0.0.0/16
• Subnet CIDR Block: 10.0.1.0/24

Here's what this means:

1. VPC IPv4 CIDR Block (10.0.0.0/16):

   • The VPC's overall address range spans from 10.0.0.0 to 10.0.255.255.
   • This provides a total of 65,536 IPv4 addresses (2^16).

2. Subnet CIDR Block (10.0.1.0/24):

   • The subnet is a smaller part of the VPC's address space.
   • The subnet's address range is from 10.0.1.0 to 10.0.1.255.
   • This provides a total of 256 IPv4 addresses (2^8).

The reason for having subnets with smaller CIDR blocks within the VPC is to logically divide the VPC's IP address space. Subnets are associated with specific availability zones, and this division allows you to isolate resources, control traffic flow, and implement different networking requirements within your VPC.

In practice, you might create multiple subnets within a VPC, each serving a different purpose (e.g., public subnet, private subnet). The choice of CIDR blocks for subnets is a design decision based on your network requirements and the number of resources you plan to deploy in each subnet.