Which two characteristics describe IS-IS? (Choose two.)
A . A collection of Level 1 routers serves as the IS-IS backbone
B . Level 2 routers connect areas in an IS-IS autonomous system
C . A collection of Level 2 routers serve as the IS-IS backbone
D . A Level 1 IS routes between areas and toward other autonomous systems
Answer: BC
Explanation:
Reference: https://www.juniper.net/documentation/en_US/junos/topics/concept/isis-levelsunderstanding.html