Schema master must be running Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2
At least one global catalog server must be running Windows Server 2008 R2, Windows Server 2012, or Windows Server 2012 R2 in sites where Exchange Server is installed
Domain and forest functional levels must be at least Windows Server 2008
DNS
Must be configured to enable domain controller and global catalog server name resolution