Which statement about a type 4 LSA in OSPF is true?
A.
It is an LSA that is originated by an ABR, that is flooded throughout the AS, and that describes a
route to the ASBR.
B.
It is an LSA that is originated by an ASBR, that is flooded throughout the AS, and that describes a
route to the ASBR.
C.
It is an LSA that is originated by an ASBR, that is flooded throughout the area, and that describes a
route to the ASBR.
D.
It is an LSA that is originated by an ABR, that is flooded throughout the AS, and that describes a
route to the ABR.
E.
It is an LSA that is originated by an ABR, that is flooded throughout the area, and that describes a
route to the ASBR.
Type-4 LSA’s are generated by an ABR for ASBR’s that are NOT located inside of that area. The type-4 LSA is used to ‘make sense’ of the Type-5 external LSA which is injected into another area (pointing to the ASBR’s RID and making that node in the database reachable).
I say A, Imagine the LSA 1 starts in area 1. When it gets to the ABR it is flooded to the area 0 as an LSA 4 and on the other side of area 0 it keeps going to any remaining areas making E wrong.
LSA Type 4 (called Summary ASBR LSA) is generated by the ABR to describe an ASBR to
routers in other areas so that routers in other areas know how to get to external routes throughthat ASBR.