I came across this question on a practice exam.
Which two statements about the isis routing protocol are true? (Choose two.)
A. - isis is capable of supporting ipv4 and ipv6
B. - isis is only capable of supporting ipv6 and clns
C. - isis routers use esis hellos to establish and to maintain neighbor relationships
D. - isis routers run the Bellman-Ford algorithm against LSDB for route selection
E. - level 1 routers learn about paths within the area of which they are a part
F. - level 2 routers learn about paths both within areas and between areas
I chose A and E and that's what the exam shows for an answer, but shouldn't F also be true?
Is the below assumption correct?
If all links in the diagram are L2 links, then RT3 would receive the inter-area routes. If the link between RT1 and RT2 was changed to a Level 1, then RT3 would NOT receive the inter-area routes.
If this is true, then response F from above is only sometimes true which would then make sense to me as to why it wasn't a correct answer
Your assumption is correct, if you change the link between RT1 and RT2 to level-1, since theses 2 routers are in 2 different areas you loose your ISIS adjacency and you will not receive any routes from RT1