Don't Forget The Operations Masters
Many IT people would add DCs to the existing Windows network some times after the first implement. At the same time, many IT people like to remove some early DCs from the network because their newly added ones are more powerful.
However, many IT people meet problems. Their domain no longer functioning properly after removing the early (exactly first) DCs. This is because the first DC is by default the Operations Master. Before removing it from the network, the administrator needs to run “dcpromo” to demote the DC to a member server. During this process it will automatically transfer the Operations Master roles to other DCs.
So, remember that even in the Windows Server 2003 domains, the DCs are not equal. Don't forget the Operations Master roles when removing old servers.