Lesson Summary: Elastic IP (EIP) and Elastic Network Interfaces (ENI) give us a flexible way to retain the same IP address on an instance. This ability is useful in many application scenarios. With ENI, settings such as IP addresses and security groups migrate with the interface. Instances must still be in public subnets to be accessible with either. This lesson shows how to use each and some of the behaviors we need to be aware of as SysOPs Administrators.