AWS VPC Introduction

What is AWS VPC?

• VPC stands for Virtual Private Cloud.
• A virtual private cloud (VPC) is a virtual network dedicated to your AWS account.
• Amazon Virtual Private Cloud provides a logically isolated area of the AWS cloud where you can launch AWS resources in a virtual network that you define.
• VPC allows the user to select IP address range, create subnets, and configure route tables, network gateways, and security settings, etc
• You can provide multiple layers of security, including security groups and network access control lists, to help control access to Amazon EC2 instances in each subnet.
• You can have multiple VPCs in a region and have a max 5 VPC per region — soft limit)
• We can add max 5 CIDR per VPC and for each CIDR minimum size is /28 = 16 IP Addresses and maximum size is /16 = 65536 IP Addresses.

Where VPCs live?

• All VPCs are created and exist in one and only one AWS region.
• AWS regions are geographic locations around the world where Amazon data centers are clustered within regions.
• Each Amazon account can host multiple VPCs because VPCs are isolated from each other.
• We can have multiple VPC in the same region with different CIDR.

Default and Custom VPCs

• If your account was created, it comes with a default VPC.
• New instances are launched into default VPC if no subnet is specified
• It has a default subnet in each Availability Zone and it is ready for you to use.
• You can launch instances into your default VPC without needing to know anything about Amazon VPC.
• Default VPCs are assigned a CIDR range of 172.31.0.0/16. Default subnets within a default VPC are assigned /20 netblocks within the VPC CIDR range.

You can also create your own Custom VPC, and configure it as you need. This is also known as a nondefault VPC.

VPC State