Which two statements about IS-IS are correct? (Choose two.)
Which two statements about IS-IS are correct? (Choose two.)
A Level 1 router can only form adjacencies with other Level 1 routers, which makes C correct. Additionally, Level 2 routers can form adjacencies with either Level 1 or Level 2 routers, confirming D is also correct.
Just correting, B and C are correct: A Level 1/Level 2 system sets the attached bit in the Level 1 PDUs that it generates into a Level 1 area to indicate that it is a Level 2-attached backbone router and that it can be used to reach prefixes outside the Level 1 area. Only L1/L2 routers can be form adjacency with L1 and L2 routers.
correct
B& C correct
CD ia correct