A cluster should contain two or more instances of a product that are configured to run within the same domain. To make an instance a member of the cluster, you must configure it to either of the available membership schemes., which are as follows:
- Well Known Address (WKA) membership scheme
- Multicast membership scheme
- AWS membership scheme
The Well-Known Addresses (WKA) feature is a mechanism that allows cluster members to discover and join a cluster using unicast instead of multicast. WKA is enabled by specifying a small subset of cluster members (referred to as WKA members) that are able to start a cluster. The WKA member starts the cluster and the other members join the cluster through this WKA member. If When the WKA member is down, the cluster breaks, and the members will not be able to cannot communicate with each other.
The system should have at least two well-known address (WKA) members in order to work correctly and to recover if a single WKA member fails.