easyMultiple Choice
350-401 Practice Question: In OSPF, which LSA type is used to describe…
In OSPF, which LSA type is used to describe routes to networks within the same area and is generated by the router that owns the network?
⚠ Common exam trap
Cisco often tests the distinction between the router that originates the LSA (Type 1) versus the DR that generates the LSA for the network segment (Type 2), causing candidates to confuse the 'owner' of the network with the DR's role.
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 (Router LSA)
Type 1 (Router LSA) is correct because each OSPF router generates a Type 1 LSA to describe its directly connected links and networks within the same area. This LSA is flooded only within the originating area and is the fundamental building block for intra-area route calculation using the SPF algorithm.
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 (Router LSA)
Why this is correct
Type 1 Router LSAs are originated by every OSPF router to advertise its own active interfaces and connected neighbors, including link type, link ID, interface IP, and metric. These LSAs are always confined to the area in which they are generated and form the base graph that Dijkstra's SPF algorithm processes. Because every router must describe itself before any other LSA can be interpreted, Type 1 is the most basic and essential LSA type.
- ✗
Type 2 (Network LSA)
Why it's wrong here
Type 2 Network LSAs are not originated by each router but only by the designated router (DR) on a broadcast or NBMA segment. The DR builds the LSA with the DR's interface IP and the Router IDs of all routers attached to that segment, creating a fake network node that enables other routers to calculate a multi-access segment efficiently. This makes Type 2 a derivative of Type 1 LSAs, not the foundational LSA type.
- ✗
Type 3 (Summary LSA)
Why it's wrong here
Type 3 Summary LSAs are generated exclusively by Area Border Routers (ABRs) to advertise prefixes that exist in one area into another area, effectively summarizing inter-area routes. They describe network reachability, not the ABR's own physical links, and they are produced only after Type 1 LSAs have been exchanged inside each area. Therefore, Type 3 cannot be the most basic LSA type.
- ✗
Type 5 (External LSA)
Why it's wrong here
Type 5 External LSAs are originated solely by Autonomous System Boundary Routers (ASBRs) to inject routes from outside OSPF, such as redistributed static or EIGRP routes, into the OSPF domain. These LSAs describe external prefixes with a forwarding address and external route tags, and they have no relationship to a router's internal link-state description. Since they represent external reachability, they cannot replace the fundamental Type 1 Router LSA.
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.
Go deeper
Related to this question
About these practice questions
Courseiva writes every 350-401 question from scratch — 1,923 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.