Recently i was discussing with one of my customer, he updated a issue relevant with his upgrade. Recently he downloaded the recent Exchange 2007 SP2 & tried upgrading to Exchange 2007 SP2 in an Active Directory forest that has only Windows Server 2008 R2 Domain Controllers. He tried to run the setup, but it fails if all domain controllers are running Windows Server 2008 R2 with the following error message.

[ERROR] Cannot find at least one domain controller running Windows Server 2003 Service Pack 1 or later in domain 'DC=DCName,DC=com,DC=DCName'. This could be the result of moving domain controller objects in Active Directory. Check that at least one domain controller running Windows Server 2003 Service Pack 1 or later is located in the 'Domain Controllers' organizational unit (OU) and rerun setup.

Yesterday during my search, i found Nasir Ali’s blog post @ Exchange Team blog – answers the queries.