If the master IP address has a problem, such as a duplicate IP address on the network, the Clusters plug-in might not be able to connect to the master IP address to allow you to manage the cluster. The My Clusters page uses the IP address found in the Cluster object by default. If the master IP address does not respond, you cannot connect to the master IP address to manage the cluster in iManager.
In OES 11 SP2 and later, you are prompted to use the server IP address of a specified node to manage the cluster while you fix the problem. See Section 9.12, Viewing or Modifying the Cluster Master IP Address or Port.