Router>ena
Router#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#hostname HaNoi
HaNoi(config)#int s0
HaNoi(config-if)#ip address 12.0.0.2 255.255.255.252
HaNoi(config-if)#clock rate 64000
HaNoi(config-if)#no shut
%LINK-3-UPDOWN: Interface Serial0, changed state to up
HaNoi(config-if)#exit
HaNoi(config)#router ospf 12
HaNoi(config-router)#network 12.0.0.0 0.0.0.3 area 0
HaNoi(config-router)#exit
HaNoi(config)#router ospf 12
HaNoi(config-router)#network 12.0.0.0 0.0.0.3 area 0
HaNoi(config-router)#exit
HaNoi(config)#^Z
%SYS-5-CONFIG_I: Configured from console by console

HaNoi#show ip ospf database 

       OSPF Router with ID (12.0.0.2) (Process ID 12)

         Router Link States (Area 0) 

Link ID         ADV Router      Age         Seq#       Checksum Link count
                     0   0x80000002    0x5073 
12.0.0.2        12.0.0.2           0   0x80000006    0x6176 
11.0.0.2        12.0.0.1           0   0x80000005    0x9024