Following these guidelines for configuring groups of Proxy Servers into clusters:
All servers to be included in a particular cluster must be installed prior to creating any clusters.
All servers in a cluster must be the same type (UNIX or Windows). Clusters must be homogenous.
All servers in a cluster must be Proxy Server version 4. Only Proxy Server version 4 servers are supported for addition to clusters.
All Administration Servers must use the same protocol, HTTP or HTTPS. If you change the protocol of one Administration Server in a cluster, you must change the protocols for all Administration Servers. For more information, see Modifying Server Information.
All cluster-specific Administration Servers must have the same user name and password as the master Administration Server. Distributed administration can be used to configure multiple administrators on each Administration Server.
One cluster-specific Administration Server must be designated as the master Administration Server, which server you choose does not matter.
The master Administration Server must have access to each cluster-specific Administration Server. The master Administration Server retrieves information about all installed Sun Java System Web Proxy Servers.