All databases have a schema which is a formal definition (set of rules) which govern the database structure and types of objects and attributes which can be contained in the database. The schema contains a list of all classes and attributes in the forest.
The schema keeps track of:
- Classes
- Class attributes
- Class relationships such as subclasses (Child classes that inherit attributes from the super class) and super classes (Parent classes).
- Object relationships such as what objects are contained by other objects or what objects contain other objects.
There is a class Schema object for each class in the Active Directory database. For each object attribute in the database, there is an attributeSchema object.
PartitionsActive Directory objects are stored in the Directory Information Tree (DIT) which is broken into the following partitions:
- Schema partition - Defines rules for object creation and modification for all objects in the forest. Replicated to all domain controllers in the forest. Replicated to all domain controllers in the forest, it is known as an enterprise partition.
- Configuration partition - Information about the forest directory structure is defined including trees, domains, domain trust relationships, and sites (TCP/IP subnet group). Replicated to all domain controllers in the forest, it is known as an enterprise partition.
- Domain partition - Has complete information about all domain objects (Objects that are part of the domain including OUs, groups, users and others). Replicated only to domain controllers in the same domain.
- Partial domain directory partition - Has a list of all objects in the directory with a partial list of attributes for each object.
The DIT holds a subset of Active Directory information and stores enough information to start and run the Active Directory service
