A great part of network administration involves management of users, computers, and groups. A successful operating system must ensure that only properly authenticated users and computers can logon to the network and that each network resource is available only to authorized users. In the Microsoft® Windows® server operating systems, the Active Directory™ service plays several major roles in providing security. Among these roles are the efficient and effective management of user logon authentication and user authorization. Both are central features of the Windows security subsystem and both are fully integrated with Active Directory.