When first installed, Windows NT4/200x/XP are preconfigured with certain user, group, and alias entities. Each has a well-known RID. These must be preserved for continued integrity of operation. Samba must be provisioned with certain essential domain groups that require the appropriate RID value. When Samba-3 is configured to use tdbsam, the essential domain groups are automatically created. It is the LDAP administrator's responsibility to create (provision) the default NT groups.

Each essential domain group must be assigned its respective well-known RID. The default users, groups, aliases, and RIDs are shown in Well-Known User Default RIDs.