Check to see if an instance is using an EIP

The easiest way to check whether or not an instance is using an EIP is to see if the public DNS matches the EIP address of your Elastic IP.  (It's helpful to add the IP address in the name of the Elastic IP.)

NOTE:   The "User Data" information does not list the current IP address of the instance; it lists the IP address that was originally used to launch the instance, so sometimes it does not match the "Public DNS name."