Without configuration, slpd listens for multicast and for UDP/TCP unicast on the default network interface. If unicast and multicast routing is enabled between interfaces on a multihomed machine, no additional configuration is needed. This is because multicast packets that arrive at another interface are properly routed to the default. As a result, multicast requests for DA or other service advertisements arrive at slpd. If routing is not turned on for some reason, configuration is required.