Global Catalog Technical Reference
The global catalog is a distributed data repository that facilitates searching and logons in an Active Directory directory service forest. The global catalog allows users and applications to locate objects in any domain in the forest by searching on an important attribute of the object (for example, search on the user’s last name to locate the user object or search on a building name to find a printer in that building). The global catalog facilitates logons by ensuring that membership in universal groups from all domains are represented in the user’s access credentials. One or more domain controllers are designated as global catalog servers because they host the global catalog, which is built automatically by the Active Directory replication system.
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