In an APPN network, when VTAM® receives a session initiation or directory search request for a resource, VTAM checks its directory services database for the location of the resource. The directory services database contains information about the location of resources obtained through resource definition, resource registration, and as the result of successful searches. If the resource is not located in that VTAM database, VTAM issues a broadcast search to all other APPN nodes or a search to a central directory server, if one is available. If there are interchange nodes in the network, at the end of a broadcast search, they are sequentially allowed to search the subareas to which they are attached. VTAM uses a cross-subnetwork search to search across a subnetwork boundary.