r1(config)#router ospf 100
r1(config-router)#net
r1(config-router)#net 192.168.1.0 0.0.0.255 area 0

r2(config)#router ospf 100
r2(config-router)#net
r2(config-router)#network 131.16.24.0 0.0.0.255 area 0
r2(config-router)#net 192.168.1.0 0.0.0.255 area 0

r3(config)#router ospf 100
r3(config-router)#network 192.168.1.0 0.0.0.255 area 0
r3(config-router)#network 172.16.1.0 0.0.0.255 area 0

r4(config)#router ospf 100
r4(config-router)#network 172.16.1.0 0.0.0.255 area 0
r4(config-router)#network 10.1.1.0 0.0.0.255 area 0
r4(config-router)#network 10.2.2.0 0.0.0.255 area 0

r3#show 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 not set

     172.16.0.0/24 is subnetted, 1 subnets
C       172.16.1.0 is directly connected, Serial1/2
     10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
O       10.2.2.0/24 [110/65] via 172.16.1.2, 00:00:03, Serial1/2
O       10.1.1.1/32 [110/65] via 172.16.1.2, 00:00:03, Serial1/2
C    192.168.1.0/24 is directly connected, FastEthernet0/0

r4#show ip access-lists
Standard IP access list 10
    10 permit 192.168.1.1 (45 matches)
    20 permit 192.168.1.3 (15 matches)
    40 permit 172.16.1.1 (63 matches)
    30 permit 131.16.24.0, wildcard bits 0.0.0.255 (45 matches)

r4#show ip int s1/2
Serial1/2 is up, line protocol is up
  Internet address is 172.16.1.2/24
  Broadcast address is 255.255.255.255
  Address determined by setup command
  MTU is 1500 bytes
  Helper address is not set
  Directed broadcast forwarding is disabled
  Multicast reserved groups joined: 224.0.0.5
  Outgoing access list is not set
  Inbound  access list is 10
  Proxy ARP is enabled
  Local Proxy ARP is disabled
  Security level is default
  Split horizon is enabled
  ICMP redirects are always sent
  ICMP unreachables are always sent
  ICMP mask replies are never sent
  IP fast switching is enabled
  IP fast switching on the same interface is enabled
  IP Flow switching is disabled
  IP CEF switching is enabled
  IP CEF Feature Fast switching turbo vector
  IP multicast fast switching is enabled
  IP multicast distributed fast switching is disabled
  IP route-cache flags are Fast, CEF
  Router Discovery is disabled
  IP output packet accounting is disabled
  IP access violation accounting is disabled
  TCP/IP header compression is disabled
  RTP/IP header compression is disabled
  Policy routing is disabled
  Network address translation is disabled
  BGP Policy Mapping is disabled
  WCCP Redirect outbound is disabled
  WCCP Redirect inbound is disabled
  WCCP Redirect exclude is disabled

r1#ping 172.16.1.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 120/140/164 ms

r2#ping 172.16.1.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
U.U.U.
Success rate is 0 percent (0/5)

r2#ping
Protocol [ip]:
Target IP address: 172.16.1.2
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 131.16.24.1
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.2, timeout is 2 seconds:
Packet sent with a source address of 131.16.24.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 100/124/140 ms