Before you deploy ISA Server 2004 Enterprise Edition, you have to consider where you are going to locate the Configuration Storage servers, which store the configuration for all of the ISA Server arrays in the enterprise. Some of the aspects you should consider are:
The number of Configuration Storage servers that you want to install for failover/redundancy.
The amount of bandwidth available for synchronization of the servers.
Hardware availability - we recommend that the Configuration Storage server be behind the ISA Server firewall, not on the same computer. Additional Configuration Storage servers therefore require additional hardware.
More detailed information on these considerations, and other important information on enterprise deployment planning, is available in the document Deployment Guidelines for ISA Server 2004 Enterprise Edition.
Thanks for the useful information.