CCNA Cisco Certified Network Associate Study Guide - FTP Server

254 Chapter 5 � IP Routing
To configure a default route, you use wildcards in the network address
and mask locations of a static route. Think of a default route as a static route
that uses wildcards instead of network and mask information. In this section,
you’ll create a default route on the 2501C router.
Router 2501C is directly connected to networks 172.16.40.0 and
172.16.50.0. The routing table needs to know about networks 172.16.10.0,
172.16.20.0, and 172.16.30.0. To configure the router to route to the other
three networks, I placed three static routes in the routing table. By using a
default route, you can just create one static route entry instead. First, you
must delete the existing static routes from the router, then add the default
route.
2501C(Config)#no ip route 172.16.10.0 255.255.255.0
172.16.40.1
2501C(Config)#no ip route 172.16.20.0 255.255.255.0
172.16.40.1
2501C(Config)#no ip route 172.16.30.0 255.255.255.0
172.16.40.1
2501C(Config)#ip route 0.0.0.0 0.0.0.0 172.16.40.1
If you look at the routing table now, you’ll see only the two directly connected
networks, plus an S*, which indicates that this entry is a candidate for
a default route.
2501C#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M –
[output cut]
- IS-IS level-1, L2 - IS-IS level-2, * - candidate
default U - per-user static route, o – ODR
Gateway of last resort is 172.16.40.1 to network 0.0.0.0
172.16.0.0/24 is subnetted, 5 subnets
C 172.16.50.0 is directly connected, Ethernet0
C 172.16.40.0 is directly connected, Serial0
S* 0.0.0.0/0 [1/0] via 172.16.40.1
2501C#
Notice also in the routing table that the gateway of last resort is now set.
However, there is one more command you must be aware of when using
default routes: the ip classless command. All Cisco routers are classful