A verification plan shows a network diagram with branch office Routers B1 through B100,
plus two ABRs, ABR1, and ABR2, all in area 100. The branches connect to the ABRs using
Frame Relay point-to-point subinterfaces. The verification plan lists the output of the show ip
ospf database summary 10.100.0.0 command on a router B1, one of the branches. Which of
the following is true regarding the output that could be listed for this command?

A.
The output lists nothing unless 10.100.0.0 has been configured as a summary route using
the area range command.

B.
If 10.100.0.0 is a subnet in area 0, the output lists one Type 3 LSA, specifically the LSA
with the lower metric when comparing ABR1’s and ABR2’s LSA for 10.100.0.0.

C.
If 10.100.0.0 is a subnet in area 0, the output lists two Type 3 LSAs, one each created by
BR1 and ABR2.

D.
None, because the Type 3 LSAs would exist only in the ABR’s LSDBs.

Explanation:
Each ABR, by definition, creates a single Type 3 LSA to represent a subnet known
in one area to be advertised into another areA. Assuming 10.100.0.0 is a subnet in area
0, both ABR1 and ABR2 would advertise a Type 3 LSA into area 100. The show ip
ospf database summary command specifically lists type 3 network summary LSAs.