Active Directory is a technology created by Microsoft that provides a variety of network services, including:

• LDAP-like directory services
• Kerberos-based authentication
• DNS-based naming and other network information

Using the same database, for use primarily in Windows environments, Active Directory also allows administrators to assign policies, deploy software, and apply critical updates to an organization. Active Directory stores information and settings in a central database. Active Directory networks can vary from a small installation with a few computers, users and printers to tens of thousands of users, many different domains and large server farms spanning many geographical locations. Active Directory was previewed in 1999, released first with Windows 2000 Server edition, and revised to extend functionality and improve administration in Windows Server 2003. Additional improvements were made in Windows Server 2003 R2. Active Directory was refined further in Windows Server 2008 and Windows Server 2008 R2 and was renamed Active Directory Domain Services. Active Directory was called NTDS (NT Directory Service) in older Microsoft documents. This name can still be seen in some Active Directory binaries. There is a common misconception that Active Directory provides software distribution. Software distribution is run by a separate service that uses additional proprietary schema attributes that work in conjunction with the LDAP protocol. Active Directory does not automate software distribution, but provides a mechanism by which other services can provide software distribution.