NAT gateways hide information about your resources while still allowing communication with the outside internet. They work by translating a private IP address into a different public IP address and remembering the translation and connection state when your internal resources request outside communication. Anything in the public internet is blocked from doing the reverse and never knows the real IP address of the resource in the private subnet.

In AWS, a NAT gateway is a managed service that automatically scales to meet internet traffic requirements. Some AWS regions and Availability Zone (AZ) do not support a NAT gateway and a NAT instance must be used. A NAT instance is an EC2 instance with software to handle NAT activities. You will need to manage and monitor a NAT instance, but it maybe a cheaper option for you when the internet traffic is low even if a NAT gateway is available in your region. We will use quick start to create the environment that automatically checks for a NAT gateway support and creates a NAT instance if it is not available.