If dynamic definition of resources is allowed and if no predefined CDRSC is located, VTAM® automatically creates a CDRSC for the logical unit as part of routing. After the owning SSCP is found by trial-and-error routing of the session initiation request, the dynamically defined CDRSC is updated with the real network ID and owning SSCP name.

For releases of VTAM before Version 4, if two hosts attempt to establish a cross-network session with a logical unit that is not predefined in either of the initiating hosts, a conflict can arise in any intermediate host that receives these requests. The receiving host will then issue a sense code indicating duplicate DLU names. The sessions can be successfully established if the requests can be rerouted. This situation can be avoided, however, by predefining the DLU with NETID or by using the NetView® alias name translation facility or the alias function of the session management exit routine to define the name of the resource instead of allowing it to be dynamically defined.