A domain controller is a machine that is able to answer logon requests from network workstations. Microsoft LanManager and IBM LanServer were two early products that provided this capability. The technology has become known as the LanMan Netlogon service.

When MS Windows NT3.10 was first released, it supported a new style of Domain Control and with it a new form of the network logon service that has extended functionality. This service became known as the NT NetLogon Service. The nature of this service has changed with the evolution of MS Windows NT and today provides a complex array of services that are implemented over an intricate spectrum of technologies.