Feb 06 2010
Upgrading Active Directory to Windows server 2008, when Exchange server 2000 or Exchange server 2003 is installed
For more detailed information also about Exchange 2007 and Exchange 2010 see “Exchange Server and it’s relationship to Active Directory“
To upgrade an Active directory forest/domain to a newer OS version you have to check some prerequisites.
If Exchange 2000 is running in the existing Windows domain, then first check with the following article that no mangled attributes exist, applies also to Windows Server 2008. http://support.microsoft.com/?id=314649
If Exchange 2000 Service pack 3 is installed, it can be used in an Active Directory Forest that contains Windows Server 2008 DCs but the Windows server 2008 DCs shouldn’t be in the same site as the Exchange 2000 server. If Windows Server 2008 DCs MUST run in an AD site that has Exchange 2000 servers, you have to configure the Directory Service Access (DSAccess) on the Exchange 2000 Server servers in the site, to use a DC that is running either Windows server 2003 or Windows server 2000. Configuring DSAccess manual will NOT provide any fallback to another Domain controller or Global catalog server. http://support.microsoft.com/kb/250570
UPDATE: Exchange 2000 isn’t supported to be used with Windows server 2008 DCs according to the “Exchange Server Supportability Matrix” but should work according to the article from the Exchange specialists “Exchange Server and Windows Server 2008“.
If Exchange 2003 is used, make sure that Exchange 2003 Service pack 2 is installed.
RODCs can be used without any problem in the forest but each Exchange server version requires a writeable Domain controller and a writeable Global catalog server.
UPDATE: According to the “Exchange Server Supportability Matrix” it is also supported to use Windows server 2008 R2 Dcs, when Exchange 2003 SP2 is installed.