Refer to the Exhibit.
The IGP is IS-IS. R2 has configured its loopback interface in Level 2 only. Referring to the exhibit,
which statement is true?
A.
R2 advertises its loopback address to all L1 adjacencies.
B.
R1 cannot reach R2’s loopback address.
C.
R1 uses a default route to reach R2’s loopback address.
D.
R1 automatically selects R2 as the default gateway to reach R2’s loopback address.
this question does not make sense. The links going between areas cannot be L1 links.
Therefore I think the answer is B.
the answer is D shortest path
R1 is a L1 routers, so it can’t be aware of the existence of L2 informations such the loopback address of R2.
As such it has to rely on the two default routes that it has generated after the neighborships with R2 and R4 went up.
That said, right answer is C ( we don’t know which one of the two routes it prefers )