The EMS_ENGINE table is used when you are running IEP in cluster mode. The EMS_ENGINE table contains the following columns:
ID. A value that uniquely identifies the IEP instance (instance1, instance2, and so on). If you are not running IEP in cluster mode, then the value is stand-alone.
INSTANCE_LOCATION. The IP address of the computer where the IEP instance is running.
LEASE_EXPIRATION. A timestamp that the cluster nodes use to determine which IEP instance is active.