Node Auto Discovery (Memcached)
For clusters running the Memcached engine, ElastiCache supports Auto Discovery—the ability for client programs to automatically identify all of the nodes in a cache cluster, and to initiate and maintain connections to all of these nodes.
Auto Discovery is only available for cache clusters running the Memcached engine. Redis cache clusters are single node clusters, thus there is no need to identify and track all the nodes in a Redis cluster.
With Auto Discovery, your application does not need to manually connect to individual cache nodes; instead, your application connects to one Memcached node and retrieves the list of nodes. From that list your application is aware of the rest of the nodes in the cluster and can connect to any of them. You do not need to hard code the individual cache node endpoints in your application.
All of the cache nodes in the cluster maintain a list of metadata about all of the other nodes. This metadata is updated whenever nodes are added or removed from the cluster.