This question is more theoretical. I am studying to certify in AWS, I am reading the aws certified solutions architect study guide for the second time and it is not clear to me what is the use that can be given to an ENI, I understand that they are used to connect a VPC with other services. Could someone give me an explanation "for dummies" and some examples of use? Thank you very much.
AOverflow.com
ENI is a network interface, which incorporates some configuration, which may include IP addresses, an Elastic IP (EIP), various security groups (firewall rules), a MAC address, a source/destination verification flag, and a description . An EIN can be connected to an EC2 instance (a virtual server); the server you are connected to may change over time.
This allows you to have a long-lived ENI that can connect to many short-lived servers over its lifetime. We have ENIs that haven't changed for years that are connected to EC2 instances that are replaced every two weeks.