Tree and Forest Structure
In accordance with DNS naming standards, Active Directory domains are created in an inverted tree structure, with the root at the top. In addition, this Windows 2000 domain hierarchy is based on trust relationships — that is, the domains are linked by interdomain trust relationships.
The default interdomain trust relationships are created by the system during domain controller creation. The number of trust relationships that are required to connect n domains is n –1, whether the domains are linked in a single, contiguous parent-child hierarchy or they constitute two or more separate contiguous parent-child hierarchies.
When it is necessary for domains in the same organization to have different namespaces, create a separate tree for each namespace. In Windows 2000, the roots of trees are linked automatically by two-way, transitive trust relationships. Trees linked by trust relationships form a forest A single tree that is related to no other trees constitutes a forest of one tree.
The tree structures for the entire Windows 2000 forest are stored in Active Directory in the form of parent-child and tree-root relationships. These relationships are stored as trust account objects (class trustedDomain ) in the System container within a specific domain directory partition. For each domain in a forest, information about its connection to a parent domain (or, in the case of a tree root, to another tree root domain) is added to the configuration data that is replicated to every domain in the forest. Therefore, every domain controller in the forest has knowledge of the tree structure for the entire forest, including knowledge of the links between trees. You can view the tree structure in Active Directory Domain Tree Manager.
For more information about configuration data, see "Active Directory Data Storage" in this book.