Refer to the exhibit. OSPF is running throughout the network. You want to minimize the
propagation of LSAs into and out of Area 1.
Which OSPF feature would best to achieve this goal?
A.
stub
B.
totally stubby
C.
NSSA
D.
totally NSSA
Explanation:
We need to redistribute RIP from R1 to Area 1 so Area 3 cannot be a stub or totally stubby
area. To minimize the propagation of LSAs into and out of Area 1 we should configure it as
a totally NSSA. Notice that a NSSA allows LSA Type 3 & 7 while a Totally NSSA only allows
LSA Type 7
Note:
Both Totally Stubby Area & Totally Stubby NSSA do not accept external AS routes or interarea routes (LSA Types 3, 4 and 5). They recognize only intra-area routes and the default
route 0.0.0.0. The main difference between them is Totally Stubby NSSA accepts routes
from other AS while Totally Stubby Area does not.
Below summarizes the LSA Types allowed and not allowed in area types:
