|All nodes should be in the same subnet||Nodes can be in different networks||Amazon EC2 nodes|
|All nodes should be in the same multicast domain||No multicasting requirement||No multicasting requirement|
|Multicasting should not be blocked||No multicasting requirement||No multicasting requirement|
|No fixed IP addresses or hosts required||At least one well-known IP address or host required.||No fixed IP addresses or hosts required|
|Failure of any member does not affect membership discovery||New members can join with some WKA nodes down, but not if all WKA nodes are down.||Failure of any member does not affect membership discovery|
|Does not work on IaaSs such as Amazon EC2||IaaS-friendly||Works on Amazon EC2|
|No WKA requirement||Requires keepalive, elastic IPs, or some other mechanism for re-mapping IP addresses of WK members in cases of failure.||No WKA requirement|
Note that some production environments do not support multicast. However, if your environment supports multicast, there are no issues in using this as your 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. When the WKA member is down, the cluster breaks, and the members 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.