What is Active Directory

• Active Directory stores information about Network Components
• It allows clients to find objects within the namespace.
• The term namespace  refers to the area in which the network components are located
• For example the table of content of a book forms a namespace in which chapters can be resolved to page numbers,
• DNS is a namespace which resolves host name to IP address
• Telephone book provides the namespace for resolving names to phone numbers .
• Active directory provides a namespace for resolving the name of the network objects to objects themselves
• Every thing that Active directory tracks is considered as an object
• An object is any user,system,resource or services tracked in active directory

http://wiki.answers.com/Q/What_is_active_directory_and_how_is_it_used
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