Host routes are advertised in router links advertisements as stub networks with mask 0xffffffff. They indicate either router interfaces to point-to-point networks, looped router interfaces, or IP hosts that are directly connected to the router (e.g., via a SLIP line). For each host directly connected to the router, the following items must be configured:
The IP address of the host.
The cost of sending a packet to the host, in terms of the link state metric. There may be multiple costs configured, one for each IP TOS. However, since the host probably has only a single connection to the internet, the actual configured cost(s) in many cases is unimportant (i.e., will have no effect on routing).