DCE Directory Service Architecture
The DCE Directory Service is a distributed, replicated database service. It is distributed because the information that forms the database is stored in different places - information about one group of users and resources might be stored in one directory server, while information about a second group of users and resources is stored in a different directory server. The Directory Service is replicated because information about a given name or group of names can be stored in more than one location, for higher availability.
The Directory Service database consists of a hierarchical set of names, the namespace, which have associated attributes. Given a name, its associated attributes can be looked up in the Directory Service. For example, given the name of a print server, the Directory Service can return the printer's location. The Directory Service gives distributed system users a well-known, central place to store information, which can then be retrieved from anywhere in the distributed system.
More:
Overview of Directory Service Components
Viewpoints on the Directory Service
Related Services: Registration and Lookup Path