ilure. If all routes in a network were static, the only form of dynamic routing we would be able to employ would be the floating static route. A floating static route is a route that becomes active only if another static route is removed from the routing table. Here's an example: ip route 0.0.0.0 0.0.0.0 192.168.1.1 1 ip route 0.0.0.0 0.0.0.0 10.0.0.1 2 The primary default route points to 192.168.1.1, and has a metric of 1. The second default route points to 192.168.1.2, and has a metric of 2. Routes with the best metrics are inserted into the routing table, SO in this case, the first route will win. Should the network 192.168.1.0 become unavailable, all routes pointing to it will be removed from the routing table. At this time, the default route to 10.0.0.1 will be inserted into the routing table, since it now has the best metric for the 0.0.0.0/0 network. The floating static route allows routes to change if a directly connected interface goes down, but it cannot protect routes from failing if a remote device or link fails. Dynamic routing protocols usually allow all routers participating in the protocol to learn about any failures on the network. This is achieved through regular communi- cation between routers. Communication Between Routers Routers need to communicate with one another to learn the state of the network. One of the original routing protocols, the Routing Information Protocol (RIP), sent out updates about the network using broadcasts. This was fine for smaller networks, but as networks grew, these broadcasts became troublesome. Every host on a network listens to broadcasts, and with RIP, the broadcasts could be quite large. Most modern routing protocols communicate on broadcast networks using multi- cast packets. Multicast packets are packets with specific IP and corresponding MAC addresses that reference predetermined groups of devices. Because routing is usually a dynamic process, existing routers must be able to dis- cover new routers to add their information into the tables that describe the n