A directed search is needed when a network node server or a central directory server receives a request for an LU for which it has a location stored in its database. The search is used to verify the information. A directed search is also used by a network node server to send a search request to a central directory server if the network node server has no information about the location of a requested resource. A directed search is used by an end node to request location information about a resource from the end node network node server.