A directory service also called as named service maps the resources contained in the network to their actual address on the network.

With name service kind of directory , the user don't have to give the actual IP address of the resource just pass the name for that resource to access it.

Each resource is like an object in the directory server because everything is contained in it. Information about a resource is called as the attribute of that object.

Information can be made secure between the objects so that only permissable/allowed user can access that resource.

Directory service is nothing but a shared place , for the management ,administration and the organization of the common items that are available on the network that can have bulk of data stored in it .

Replication and Distribution are the primary features in the management of a directory.

The term replication is used to indicate that the same directory namespace (the same objects) are copied to another directory server for redundancy and throughput reasons.