How to find it:

The repadmin tool: repadmin /showattr * “cn=schema,cn=configuration,dc=Domain,dc=Com” /atts:objectVersion The following registry key: HKLM\SYSTEM\CurrentControlSet\Services\NTDS\Parameters<Schema Version #> dsquery: dsquery * CN=Schema,CN=Configuration,DC=Domain,DC=Com -Scope Base -attr objectVersion

Windows 2000 RTM (Schema version 13) Windows Server 2003 RTM (Schema version 30) Windows Server 2003 R2 (Schema version 31) Windows Server 2008 (Schema version 44) Windows Server 2008 R2 (Schema version 47)

How to Find the Current Schema Version - TechNet