Samba-3 is not, and cannot act as, an Active Directory Server. It cannot truly functions as an Active Directory Primary Domain Controller. The protocols for some of the functionality of Active Directory Domain Controllers has been partially implemented on an experimental only basis. Please do not expect Samba-3 to support these protocols. Do not depend on any such functionality either now or in the future. The Samba Team may remove these experimental features or may change their behavior. This is mentioned for the benefit of those who have discovered secret capabilities in Samba-3 and who have asked when this functionality will be completed. The answer is maybe or maybe never!
To be sure, Samba-3 is designed to provide most of the functionality that Microsoft Windows NT4-style Domain Controllers have. Samba-3 does not have all the capabilities of Windows NT4, but it does have a number of features that Windows NT4 domain contollers do not have. In short, Samba-3 is not NT4 and it is not Windows Server 200x, it is not an Active Directory server. We hope this is plain and simple enough for all to understand.