Here is my configuration: My network is a small LAN (150 user and 3 servers), only 1 domain. Server A: DC Roles(Domain Name Master, Escheme Master)+ GC Server B: DC Roles(other 3 roles of the forest) + GC Server C: Exchange 2000 Member server Questions ? 1-Server A FAIL: If Global Catalog server (Server A) go down the client computers can't contact de Exchange server. So how can I force de Exchange server to use the other Global Catalog server (Server B) ? How my Exchange Client should be able to fail over to the GC B? Note: I don't want to restart server B or C 2- In Exchange 2000 Administrative console --- Server Property---- Directory Access appear the topology of my Domain: What is the function and difference of:? DC GC Configuration server How can I mitigate the domino effect ? I want to add some redundancy for state available the Exchange server in case of one GC server go DOWN. HOW do it?