This mode of server operation involves the Samba machine being made a member of a domain security context. This means by definition that all user authentication will be done from a centrally defined authentication regime. The authentication regime may come from an NT3/4-style (old domain technology) server, or it may be provided from an Active Directory server (ADS) running on MS Windows 2000 or later.

Of course it should be clear that the authentication backend itself could be from any distributed directory architecture server that is supported by Samba. This can be LDAP (from OpenLDAP), or Sun's iPlanet, or Novell e-Directory Server, and so on.