Unicast (Well-Known Address) Cluster Member Discovery

If you cannot or do not wish to use multicast discovery in your environment, then configure unicast discovery, also known as "well-known address" or WKA discovery. These "well-known addresses" enable a newly started node to discover existing members. Unicast discovery uses the TCP protocol.

The discovery property is be.engine.cluster.as.discover.url. For unicast discovery, the value is a semicolon-separated list comprising a sub-set of all the listen URLs (which are different for each PU), using this format: 

tcp://ip:port[;ip:port]*/
Note:
One cluster node in the WKA list must be running at all times
 At least one cluster node specified in the well-known address list must be running at all times, so that other new members can join the cluster (metaspace). If all nodes specified in the well-known address list stop, then other nodes that are still running continue to function, but they print warnings to the console and no new members can connect to this cluster.
For WKA discovery, make discover URL a cluster-level property and listen URL a PU-level property
 The discover URL property (be.engine.cluster.as.discover.url) must be present and configured identically for all potential cluster members. Therefore add this property at the cluster level of the CDD file. The listen URL property (be.engine.cluster.as.listen.url) must be present and configured differently for each possible cluster member. Therefore add this property at the PU level.