RDISC is implemented by in.rdisc, which should run on both routers and hosts. Normally, when in.rdisc runs on a host, in.rdisc enters a default route for each router that is also running in.rdisc. A host that is running in.rdisc cannot discover routers that are running only RIP. Furthermore, when routers are running in.rdisc (rather than in.routed), they can be configured to have a different preference, which causes hosts to select a better router. See the rdisc(1M) man page.