Which three statements are true regarding the IS-IS link-state database (LSDB)? (Choose three.)
A.
An L1 router has a single database reflecting the connectivity of its area.
B.
An L1 router often relies on a default route generated by attached routers to reach interarea
destinations.
C.
The Level 2 database contains only backbone area routes unless route leaking is configured.
D.
Route leaking can be used to optimize Level 2 to Level 1 routing.
E.
An attached router has at least two LSDBs: one for each Level 1 area and a single LSDB for
the Level 2 backbone.
Explanation:
i believe the right answer is A,D,and E
B is wrong as default route generated by L1 router itself not the attached router
the following is written in Juniper JIR book:
Level 1 routers create a default route for interarea prefixes, which
points to the closest (in terms of metrics) Level 1 and Level 2-attached router.
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