Understand Open Shortest Path First (ospf) Design Guide

show ip ospf interface 
●
This command is a quick check to determine if all of the interfaces belong to the areas they are
supposed to be in. The sequence in which the OSPF network commands are listed is very
important.
In RTA configuration, if the "network 203.0.113.100 0.0.255.255 area 0.0.0.0" statement was put
before the "network 203.0.113.41 0.0.0.0 area 1" statement, all of the interfaces would be in area
0, which is incorrect because the loopback is in area 1.
Here is the command output on RTA, RTF, RTB, and RTD:
RTA#show ip ospf interface e0
Ethernet0 is up, line protocol is up
Internet Address 203.0.113.141 255.255.255.0, Area 0.0.0.0
Process ID 10, Router ID 203.0.113.41, Network Type BROADCAST
, Cost:
10
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 203.0.113.151
, Interface address 203.0.113.142
Backup Designated router (ID) 203.0.113.41, Interface address
203.0.113.141
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 0:00:02
Neighbor Count is 3, Adjacent neighbor count is 3
Adjacent with neighbor 203.0.113.151 (Designated Router)
Loopback0 is up, line protocol is up
Internet Address 203.0.113.41 255.255.255.255, Area 1
Process ID 10, Router ID 203.0.113.41, Network Type LOOPBACK, Cost: 1
Loopback interface is treated as a stub Host
RTF#show ip ospf interface e0
Ethernet0 is up, line protocol is up
Internet Address 203.0.113.142 255.255.255.0, Area 0.0.0.0
Process ID 10, Router ID 203.0.113.151, Network Type BROADCAST
, Cost: 10
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 203.0.113.151, Interface address 203.0.113.142
Backup Designated router (ID) 203.0.113.41, Interface address
203.0.113.141
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 0:00:08