Why Have a Directory Service?

A directory service is one of the most important components of an extended computer system. Users and administrators frequently do not know the exact name of the objects they are interested in. They may know one of more attributes of the objects and can query the directory to get a list of objects that match the attributes. For example, "Find all duplex printers in Building 26." A directory service allows a user to find any object, given one of its attributes.

A directory service can:

• Enforce security that is defined by administrators in order to keep information safe from intruders.
• Distribute a directory across many computers in a network.
• Replicate a directory to make it available to more users and resistant to failure.
• Partition a directory into multiple stores to allow the storage of a very large numbers of objects.

A directory service is both a management tool and an end user tool. As the number of objects in a network grows, the directory service becomes essential. The directory service is the hub around which a large distributed system turns.