HKLM\SYSTEM\CurrentControlSet\Services\NTDS\Parameters\<Schema Version>

– Windows 2000 RTM with all Service packs = Schema version is 13
– Windows Server 2003 RTM with all Service packs = Schema version is 30
– Windows Server 2003 R2 RTM with all Service packs = Schema version is 31
– Windows Server 2008 RTM with all Service packs = Schema version is 44
– Windows Server 2008 R2 RTM with all Service packs = Schema version is 47
– Windows Server 2012 RTM = Schema version is 56