Understanding Domain and Forest Functional Levels
Applies To: Windows Server 2008, Windows Server 2008 R2, Windows Server 2012
Domain and forest functional levels
All of the information in this topic has been updated and republished at Understanding Active Directory Domain Services (AD DS) Functional Levels. If you are only interested in how to enable domain-wide features or forest-wide features, see Raise the Domain Functional Level and Raise the Forest Functional Level.