Here is a quick reference of the Lync 2010 AD requirements.
The Active Directory environment where Microsoft Lync Server 2010 is installed must meet the following requirements:
The AD forest where Lync 2010 is deployed must have a functional level of one of the following: Windows Server 2008 R2 Windows Server 2008 Windows Server . . . → Read More: Lync Server 2010 AD Infrastructure Requirements