I took one of my DC's offline over the weekend to format & load it with Server 2008 R2, so prior to turning it off, I transferred all services to my other DC, did a DCPROMO and removed it as a domain controller.
Everything went fine, with the exception that I changed the domain controller name in Server 2008. It is still an AD server for the same domain in AD, just a different computer name.
I am currently working on an Exchange 2003 to Exchange 2010 migration, so when I logged into EMC this morning, I was presented with a "Cannot connect to Active Directory Server <OldServername>" ...
I opened Exchange Management Shell and typed "Get-ADServerSettings | fl" and none of the settings are pointing to the old DC?