VPC in AWS

Each instance has a default network interface, called the primary network interface. You cannot detach a primary network interface from an instance.

VPC is a virtual private cloud enables you to launch AWS resources into a virtual network that you have defined.

closely resembles a traditional network that operate in your own data center, with the benefits of using the scalable infrastructure of AWS

CIDR Blocks

Secondary CIDR Blocks

CIDR Blocks is prefix-based standard for the representation of IP addresses and their routing properties.

can add the secondary CIDR blocks to the VPC directly from the console or by using the CLI after they have created the VPC with the primary CIDR block

who are launching more and more resources in their VPCs, can now scale up their VPCs on-demand

no longer have to over-allocate private IPv4 space to VPCs, allocate only what is required at the time

IPv6 CIDR Blocks

standard syntax for writing IPv6 addresses with a routing prefix

It consists of an IPv6 address, a slash, then a number of bits to measure the routing prefix

Elastic Network Interface

Primary and Secondary Private IP Addresses

Each instance has a default network interface, called the primary network interface. You cannot detach a primary network interface from an instance.

Attaching Elastic Network Interface

You can attach a network interface to any of your stopped or running instances, using either the Instances or Network Interfaces pages of the Amazon EC2 console.

Public and Elastic IP Addresses

An Elastic IP address is a public IPv4 address, which is reachable from the internet.

If your instance does not have a public IPv4 address, you can associate an Elastic IP address with your instance to enable communication with the internet.