Bringing the Domain and Forest Functionality Level to Windows 2008 R2¶
Samba’s current distribution supports domain and forest functionality up to Windows 2008 R2 at most. If your tree structure is already like this, you can skip this step.
To join as DC, execute the following commands in the PowerShell (run as administrator) of the Active Directory server.
To downgrade ForestMode to 2008 R2Set-ADForestMode -Identity DOMAINNAME -ForestMode Windows2008R2Forest
To downgrade DomainMode to 2008 R2Set-ADDomainMode -Identity DOMAINNAME -DomainMode Windows2008R2Domain
Important: Your domain must not have an operating system lower than forest and domain functionality. If the Windows2008R2Forest and Windows2008R2Domain levels are to be adjusted, the operating systems of the DC’s must be Windows 2008 R2 and above. Do not change this levels without making these checks. Otherwise you may cause your DC’s to be dropped from the domain.