Active Directory serves as a common repository of information for the Windows 2000 forest.
Objects can represent a wide variety of entities.
Some of the more common object classes include users, computers, printers, organizational units, and security groups. A few, special DC's in the forest are designated as Global Catalog servers, and contain a subset of attributes for all forest objects. Forest-wide searches begin by querying a Global Catalog server, which will then refer the query to a DC containing a complete set of attributes for the queried object. The Active Directory can be customized within each W2k domain, to meet the needs of the organization associated with the domain. Since each W2k domain functions as a security boundary, objects in a given domain are completely separate entities from objects in other domains of the forest, even if the objects in separate domains seem to be similar.