H12-821_V1.0 · Question #758
In the OSPF routing protocol, the only LSA types involved in intra-area route calculation are Router LSA, Network LSA, and Summary LSA.
The correct answer is B. FALSE. B is correct because Summary LSAs (Type 3) are used for inter-area routing, not intra-area routing. Intra-area route calculation relies solely on Type 1 (Router LSA) and Type 2 (Network LSA), which are flooded within a single area to build the SPF tree. Option A is wrong…
Question
Options
- ATRUE
- BFALSE
How the community answered
(29 responses)- A24% (7)
- B76% (22)
Explanation
B is correct because Summary LSAs (Type 3) are used for inter-area routing, not intra-area routing. Intra-area route calculation relies solely on Type 1 (Router LSA) and Type 2 (Network LSA), which are flooded within a single area to build the SPF tree.
Option A is wrong because including Summary LSAs in intra-area calculation is factually incorrect - Type 3 LSAs are originated by ABRs to advertise prefixes between areas, and they never participate in the SPF algorithm run within an area.
Memory tip: Think "Intra = 1 and 2" - only Router LSA (Type 1) and Network LSA (Type 2) feed the SPF tree inside an area. Summary (Type 3), ASBR Summary (Type 4), and External (Type 5/7) LSAs all deal with routes outside the local area.
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