To check the routing tables, running the command show ip route:
Router # show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
C 192.168.1.0/24 is directly connected, Ethernet0
C 200.200.1.0/24 is directly connected, ethernet1
R 204.170.0.0/24 [120 / 5] via 172.25.2.1, 00:00:15, Serial0
R 172.16.0.0/16 [120 / 8] via 172.25.2.1, 00:00:20, Serial1
The show ip route shows a routing table where there are two directly connected networks identified with the letter C, and two learned by RIP with the letter R.
The line:
R 204.170.0.0/24 [120 / 5] via 172.25.2.1, 00:00:15, Serial0
It is interpreted as follows:
Routing Protocol R, R = RIP
204.170.0.0/24 network learns
[120 / 5] administrative distance / metric, in this case falls
172.25.2.1 via road which has been learned
00:00:15 elapsed time since the last update, RIP updates every 30 seconds.
Interface Serial0 input / output
Copy of a show ip protocols:
Router # show ip protocols
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 7 seconds
Invalid After 180 seconds, hold down 180, flushed after-240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Redistributing: rip