A directory server uses knowledge information to pass requests for information to other servers. The knowledge information held by a directory server is a reference to a directory server holding other naming contexts. When a server receives a request for information, it checks whether it can respond to the request using the information in the local data store. If it cannot, it checks the referral defined for the data store, and returns the details of an alternate directory server to the directory client.
The client can then send the request to the other directory server. Some clients contact the alternate server automatically, so the referral mechanism is transparent to users. Other clients return the referral information to the user. See "Example: The XYZ Corporation" for an example of how referrals are used.