For client applications to access services in an HA cluster in a transparent way, a virtual IP address must be supplied to the client applications. This virtual IP address is usually referred to as the "logical host." This logical host identity is a network address (or host name) and is not tied to a single cluster node.

When failover happens, the cluster control software will resolve the virtual IP address to the physical IP address of the active node in the cluster. (A virtual IP address is like any other IP address except it does not have a specific host or node to resolve to. It resolves at run time to a node wherever the IP is physically bound and reachable on the network.) The client application should not be affected in any way other than experiencing a brief outage of the services.