Domain Security

Security is one of the primary reasons for Active Directory's existence. First off, all of the account names and passwords reside on a single machine (the domain controller), which can easily be locked away, protected, and backed up. The multiple domain controllers automatically replicate the changes to one another, so that each one has up-to-date information.

Active Directory is also a vital part of the network's other security mechanisms. When your computer is a member of a domain, the first thing you do is log on, just as in a workgroup. But when you log into a domain, Windows 7 transmits your name and password (in encrypted form) to the domain controller, which checks your credentials and grants or denies you access.