Active Directory (AD) is a structure used on computers and servers running the Microsoft Windows operating system (OS). AD is used to store network, domain, and user information and was originally created by Microsoft in 1996. It was first deployed on Microsoft Windows 2000.ctive Directory makes use of a ‘pull’ system to receive changes from the server. The Microsoft Knowledge Consistency Checker (KCC) makes a replication topology of site links that uses defined sites to manage traffic. Intrasite replication occurs automatically once a change notification is received.