Here is my current set up:1 domain, 1 forest2 domain controllers. One of the domain controllers holds all of the FSMO roles except Infrastructure1 domain controller with the Global Catalog1 Exchange 2007 serverWhen I take down the domain controller that holds most of the FSMO roles in addition to the Global Catalog, my Exchange Server becomes unusable. I see the following errors in the event viewer on the Exchange server: (2604) MSExchangeADAccess, (9385) MSExchangeSA and (4001) MSExchangeSystemAttendant. These only happen when that particular domain controller is offline. I've read a number of articles concerning these errors. Is it possible that I could avoid these problems by simply adding a Global Catalog destination to my other domain controller? Or would I need to transfer FSMO roles to the other domain controller as well. My goal is to have e-mail accessible even if one of my domain controllers is down for maintenance.

Hi brown26 The Exchange Server needs a GC, so making your second server a GC should allow you to take down your DC and still have the Exchange Server available. You don't need to transfer any FSMO roles. It is generally considered best practice to make all DCs GCs in single domain forests. There is very little overhead in doing so and it means you have failover for outage of a single DC/GC. In addition to Exchange availability, user domain logons require a GC. Tony

I agree with Tony.It is best practice to have two Global Catalog servers in the same site available for Exchange 2003/2007. Exchange 2007 is very intensive on Active Directory and the Global Catalog servers. In the event one server goes down Exchange will still be able to function.SF - MCITP:EMA, MCTS

Yes, we need to have a GC running in the site Resources: Network and Directory Servers table in Exchange 2007 System RequirementsGlobal Catalog Defined section in Why you need Active Directory for Exchange Server 2007