To establish a session, the location of the partner resource must be known to VTAM®. If the location of the partner resource is not statically defined, it can be monitored dynamically as a result of a directed, broadcast, or cross-subnetwork search. A directed search is used when VTAM has location information for the resource as the result of a previous search or if there is a central directory server in the network. A broadcast search is used when VTAM has no information about the location of the resource. A cross-subnetwork search is used to determine the location of a partner resource in another subnetwork.

A VTAM network operator can also initiate a search for a resource. Unlike searches that are performed for session initiation requests, an operator-initiated search does not update the directory services database when a resource is found.