esign problem receiving the advertisement for 10.0.0.0 from Router A, Router B inserts the entire 10.0.0.0/8 network into its routing table. Router C has a different 10 network attached: 10.20.20.0/24. Again, RIP advertises the 10.0.0.0 network from Router C without a subnet mask. Router B has now received another advertisement for 10.0.0.0/8. The network is the same, the protocol is the same, and the hop count is the same. When a newer update is received for a route that has already been inserted into the routing table, the newer update is considered to be more reliable and is inserted into the routing table, overwriting the previous entry. This means each time Router B receives an update from Router A or Router C, it will change its routing table to show that network 10.0.0.0 is behind the router from which it received the update. You might be tempted to say that the networks behind Routers A and C in Fig- ure 10-9 are different, but from RIP's point of view, you would be wrong. Technically, the networks behind Routers A and C are the same. They are both part of the 10.0.0.0/8 network. The routers are connected to different subnets within the 10.0.0.0/8 network, which is why RIP has a problem with the design. The only other type of network that RIP understands is a host network. RIP can ad- vertise a route for a /32 or 255.255.255.255 network. Because RIP does not include subnet masks in its updates, a route is determined to be a host route when the address of the network is anything other than a normal network address. Configure routing protocols in IOS using the router command. The protocol name is included in the command, which puts the router into router configuration mode: Router-A (config)#router rip Router-A (config-router): On modern routers that support RIPv2, if you wish to use RIPv1, you must specify it explicitly in the router configuration, because RIPv2 is used by default: router rip version 1 Chapter 10: Routing Protocols By default, no interfaces are included in the routing protocol. This means 