If A, B, and C are all registered members of a group and C unregisters, A and B will receive a membership update with only A and B. This message is identical to the message that would be generated if C failed. To distinguish these two events, we assume that the client uses the broadcast4messaging facility to announce its intention to leave the group. When a node leaves the group intentionally, this is not a big issue. When a node fails, a global atomic broadcast facility sends a membership update to every other node in the list. One of the remaining nodes (we can select the node with the smallest id) that shares the log disk with the failed node, replays the log of the failed node. Similarly, if a node joins the group, the new node has to be synchronized with the rest of the nodes in the group.