If you are using Oracle 10g, no LogicalHostname resources are required.
Which LogicalHostname resources will Oracle listener resources use?
Use the answer to this question when you perform the procedure in Registering and Configuring Oracle Listener Resources.
If a cluster node that is running an instance of Oracle Real Application Clusters fails, an operation that a client application attempted might be required to time out before the operation is attempted again on another instance. If the Transmission Control Protocol/Internet Protocol (TCP/IP) network timeout is high, the client application might require a significant length of time to detect the failure. Typically, client applications require between three and nine minutes to detect such failures.
In such situations, client applications can connect to listener resources that are listening on an address that is represented by the Sun Cluster LogicalHostname resource. Configure the LogicalHostname resource and the listener resource in a separate resource group. Ensure that this resource group is mastered on the nodes on which Oracle Real Application Clusters is running. If a node fails, the resource group that contains the LogicalHostname resource and the listener resource fails over to another surviving node on which Oracle Real Application Clusters is running. The failover of the LogicalHostname resource enables new connections to be directed to the other instance of Oracle Real Application Clusters.