If the Diameter realm table does not contain an entry for the destination realm and the application, the request message is forwarded to the default peer, if one is configured. There can be only one default peer per Diameter node. Unlike a realm routing entry in the realm table, the default peer is application (NASREQ/Gx/Gy) unaware, and therefore it is used as a route of last resort, regardless of whether the selected path leads to a server supporting this application or not. If the default peer is not configured, messages destined for a realm that is not listed in the realm routing table are dropped.