A. No. You can have NT 4 BDCs (but never NT 4 PDCs) in Windows 2000 and Windows Server 2003 domains, but there can't be any NT 4 BDCs in the domain if you add a Server 2008 or later domain controller (DC). Windows 2000 and Server 2003 DCs are both supported in domains with Server 2008 and Server 2008 R2 DCs, except for setting domain functional levels. If you set a domain to Server 2008 domain functional level, for example, then you can only have Server 2008 and above DCs.

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