IPv4 networks use the router discovery protocol to dynamically discover the IP addresses of their neighboring routers. The router discovery protocol is discussed in the following subsection.

IPv6 networks use Neighbor Discovery to enable nodes to determine the neighbors that can be reached and to find routers that are able to forward packets for them. In IPv6 networks, the only routes that are dynamically discovered are default routes. All other routes must be statically (manually) configured using the TCPIP ROUTE command. Neighbor discovery is discussed in the subsection Using Neighbor Discovery.