Studying "ip default-network"in RIP

R1#sh ip int bri

Interface                  IP-Address      OK? Method Status                Protocol

Serial0/0                  10.1.12.1       YES manual up                    up     

Loopback2                  2.2.2.2         YES manual up                    up     

Loopback3                  3.3.3.3         YES manual up                    up     

Loopback4                  4.4.4.4         YES manual up                    up  

R2#sh  ip int bri

Interface                  IP-Address      OK? Method Status                Protocol

Serial0/0                  10.1.12.2       YES manual up                    up     

Serial0/1                  10.1.23.2       YES manual up                    up    

R3#sho ip int bri

Interface                  IP-Address      OK? Method Status                Protocol

Serial0/0                  10.1.23.3       YES manual up                    up  

R1#sho run | s rip

router rip

 version 2

 network 2.0.0.0

 network 3.0.0.0

 network 10.0.0.0

 no auto-summary

R1(config)#ip default-network 2.0.0.0

R2(config)#router rip

R2(config-router)#ver 2

R2(config-router)#net 10.0.0.0

R3(config)#router rip

R3(config-router)#ver 2

R3(config-router)#net 10.0.0.0

R3(config-router)#no au

R2#sho ip route

Codes: C - connected, S - static, 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

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

Gateway of last resort is 10.1.12.1 to network 0.0.0.0

R    2.0.0.0/8 [120/1] via 10.1.12.1, 00:00:06, Serial0/0

R    3.0.0.0/8 [120/1] via 10.1.12.1, 00:00:06, Serial0/0

     10.0.0.0/24 is subnetted, 2 subnets

C       10.1.12.0 is directly connected, Serial0/0

C       10.1.23.0 is directly connected, Serial0/1

R*   0.0.0.0/0 [120/1] via 10.1.12.1, 00:00:06, Serial0/0

R3#sho ip route

Codes: C - connected, S - static, 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

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

Gateway of last resort is 10.1.23.2 to network 0.0.0.0

R    2.0.0.0/8 [120/2] via 10.1.23.2, 00:00:16, Serial0/0

R    3.0.0.0/8 [120/2] via 10.1.23.2, 00:00:16, Serial0/0

     10.0.0.0/24 is subnetted, 2 subnets

R       10.1.12.0 [120/1] via 10.1.23.2, 00:00:16, Serial0/0

C       10.1.23.0 is directly connected, Serial0/0

R*   0.0.0.0/0 [120/2] via 10.1.23.2, 00:00:16, Serial0/0

R2#ping 4.4.4.4

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

!!!!!

R3#ping 4.4.4.4

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 4.4.4.4, timeout is 2 seconds:

!!!!!