A NAT device in your VPC will enable instances in the private subnet to trigger outbound IPv4 traffic to other AWS services/internet while hindering inbound traffic initiated on the internet. Here when traffic goes out to the internet, IP address gets replaced by NAT device’s address and when the response comes back to the instances, the device translates the address of instances back to the private IP addresses. AWS has two types of NAT devices – NAT instance and NAT gateway. Linux AMIs are configured to run as NAT instances. NAT does not support IPv6 as well.