To engage in a technical discussion of domain implementation, it is first necessary to understand basic domain concepts—accounts, servers, and domains — and the interaction between these components.
The basic unit of security and centralized administration in Windows NT is the domain, a logical grouping of servers and workstations. A Windows NT network consists of one or more domains and can be contained at one site or span different sites. The minimum requirement for a domain is one server running Windows NT Server, which serves as the Primary Domain Controller and stores the master copy of the domain's user and group database. Optionally, a domain can include other servers running Windows NT Server acting as Backup Domain Controllers, Windows NT Server computers serving as standard servers, LAN Manager 2.x servers, Windows NT Workstation clients, and other clients, such as those running Windows® for Workgroups and MS-DOS®.
The following topics are summarized here for your convenience; other pertinent concepts are covered in other Windows NT Server materials.