Overview

Active Directory (AD) is Microsoft's proprietary directory service. It runs on Windows Server and enables administrators to manage permissions and access to network resources. Active Directory stores data as objects. An object is a single element, such as a user, group, application or device such as a printer.

Active Directory stores information about objects on the network and makes this information easy for administrators and users to find and use. Active Directory uses a structured data store as the basis for a logical, hierarchical organization of directory information.

Active Directory includes:

• A set of rules, the schema, that defines the classes of objects and attributes contained in the directory, the constraints and limits on instances of these objects, and the format of their names. For more information about the schema, see Schema.
• A global catalog that contains information about every object in the directory. This allows users and administrators to find directory information regardless of which domain in the directory actually contains the data. For more information about the global catalog, see Global catalog.
• A query and index mechanism, so that objects and their properties can be published and found by network users or applications. For more information about querying the directory, see Searching in Active Directory Domain Services.
• A replication service that distributes directory data across a network. All domain controllers in a domain participate in replication and contain a complete copy of all directory information for their domain. Any change to directory data is replicated to all domain controllers in the domain. For more information about Active Directory replication, see Active Directory Replication Concepts.