In Microsoft Windows Server, a logical structure formed by combining two or more domain trees.
Forests provide a way of administering enterprise networks for a company whose subsidiaries each manage their own network users and resources. For example, a company called CarPoint might have a domain tree with the root domain carpoint.com, while a subsidiary company called Expedia might have a domain tree with the root domain expedia.com. Note that these two companies do not share a contiguous portion of the DNS namespace; this is typical of trees in a forest.
The two companies might want to administer their own users and resources but make those resources available to each other’s users. They can combine the two domain trees into a forest by establishing a two-way transitive trust between the root domains of the two trees.
Graphic D-34. Domain forest.
All trees in a forest must share a common directory schema and global catalog. The global catalog holds information about all objects in all domains of the forest and acts as an index of all users and resources for all domains in the forest.
By searching the global catalog, a user in one domain can locate resources anywhere in the forest. The global catalog contains only a subset of the attributes of each object. This ensures fast searches for users trying to locate network resources.