A network design shows area 1 with three internal routers, area 0 with four internal routers,
and area 2 with five internal routers. Additionally, one ABR (ABR1) connects areas 0 and 1,
plus a different ABR (ABR2) connects areas 0 and 2. How many Type 1 LSAs would be
listed in ABR2’s LSDB?

A.
6

B.
7

C.
15

D.
12

E.
None of the other answers is correct.

Explanation:
As an ABR connected to areas 0 and 2, ABR2 will have LSDB entries for both area 0 and
area 2. In Area 0, ABR2 learns Type 1 LSAs from the four routers internal to area 0, plus

ABR1, and plus 1 for the area 0 Type 1 LSA ABR2 creates for itselF. In area 2, ABR2 learns
1 each for the five routers internal to area 2, plus the 1 Type 1 LSA ABR2 created for itself
inside area 2. The total is 12.