hardMultiple Select
CCNP Practice Question: Which three statements about OSPF LSA types are…
Which three statements about OSPF LSA types are correct? (Choose three.)
⚠ Common exam trap
350-401 often tests the confusion between ABRs and ASBRs — candidates wrongly attribute Type 3 Summary LSAs to ASBRs, when ABRs generate Type 3 and ASBRs generate Type 5, and they forget Type 5 LSAs flood domain-wide rather than staying area-local.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Type 1 LSAs (Router LSAs) are generated by every OSPF router and describe the router's interfaces and neighbors within an area.
Option A is correct because Type 1 Router LSAs are originated by every OSPF-enabled router, are scoped to a single area, and describe that router's links (interfaces, IP addresses, metrics) and its neighbors on those links. Option B is correct because Type 2 Network LSAs are generated only by the Designated Router on multi-access segments such as broadcast and NBMA networks, and they list the DR, the BDR, and all attached routers to represent the transit network. Option D is correct because Type 4 ASBR Summary LSAs are produced by Area Border Routers to tell routers in other areas how to reach an Autonomous System Boundary Router located in a different area. Option C is wrong because Type 3 Summary LSAs are generated by ABRs to advertise inter-area routes, not by ASBRs to advertise external routes. Option E is wrong because Type 5 AS External LSAs are flooded throughout the entire OSPF autonomous system (except stub/NSSA areas), not confined to the originating area.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Type 1 LSAs (Router LSAs) are generated by every OSPF router and describe the router's interfaces and neighbors within an area.
Why this is correct
Every OSPF router originates a Type 1 Router LSA describing its own links, interface states and costs, flooded only within its area. This satisfies the requirement that each router advertises its local topology, forming the basis of the area's shortest-path tree.
- ✓
Type 2 LSAs (Network LSAs) are generated by the DR on broadcast and NBMA networks to list all routers attached to the segment.
Why this is correct
On broadcast and NBMA segments the DR originates the Type 2 Network LSA, listing every attached router's Router ID. This satisfies the requirement to represent the multiaccess segment as a single pseudonode, reducing adjacency and LSA flooding.
- ✗
Type 3 LSAs (Summary LSAs) are generated by ASBRs to advertise external routes into the OSPF domain.
Why it's wrong here
Type 3 summary LSAs are generated by ABRs to advertise inter-area routes, not by ASBRs advertising external routes. External redistribution is carried by Type 5 (or Type 7 in NSSAs) LSAs. Type 3 would be correct when summarising networks between areas at an area border router.
- ✓
Type 4 LSAs (ASBR Summary LSAs) are generated by ABRs to advertise the location of an ASBR to routers in other areas.
Why this is correct
ABRs generate Type 4 ASBR Summary LSAs to tell routers in other areas where the ASBR sits, since Type 1 LSAs do not cross area boundaries. This satisfies the requirement for inter-area reachability to external routes.
- ✗
Type 5 LSAs (AS External LSAs) are flooded only within the area where they originate.
Why it's wrong here
Type 5 AS External LSAs are flooded throughout the entire OSPF domain, except into stub, totally stubby and NSSA areas, not confined to their originating area. They are correct when redistributing external routes from an ASBR across all normal areas.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.