Below is a list of OS versions and related schema versions.

Find out the current schema version by inspecting the objectVersion property of CN=Schema,CN=Configuration,<Forest DN> For example, to find out the current schema version, use a tool like ADSIEDIT or dsquery, e.g.:

dsquery * CN=Schema,CN=Configuration,<Forest DN> -scope base –attr objectVersion

or use PowerShell:

Get-ADObject (Get-ADRootDSE).schemaNamingContext -Property objectVersion