hardMultiple ChoiceObjective-mapped
300-410 Practice Question: Two OSPF routers R1 and R2 are connected via a…
Two OSPF routers R1 and R2 are connected via a GigabitEthernet link in area 0. R1 has interface GigabitEthernet0/0 ip ospf network point-to-point, while R2 has the default OSPF network type broadcast. R1's show ip ospf neighbor shows R2 in FULL state, but R2's show ip ospf neighbor shows R1 in FULL state. However, routes from R1 are not appearing in R2's routing table. Show ip ospf database on R2 shows the router LSA from R1 but not the network LSA. What is the root cause?
⚠ Common exam trap
Cisco often tests the misconception that a FULL adjacency guarantees full route exchange, but the trap here is that OSPF network type mismatch can break route installation even when neighbor state is FULL and Router LSAs are exchanged.
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
✓
The OSPF network type mismatch causes R1 to not generate a network LSA, and R2 cannot install routes that rely on that LSA.
When R1 has the OSPF network type set to point-to-point on the GigabitEthernet link, it does not elect a DR/BDR and therefore does not generate a Type 2 (Network) LSA. R2, with the default broadcast network type, expects a Network LSA to build complete routing information for the segment. Although the adjacency reaches FULL and R2 receives R1's Type 1 (Router) LSA, the missing Network LSA prevents R2 from installing routes that depend on that LSA, such as those for networks advertised by R1 that are not directly connected to the link.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The OSPF network type mismatch causes R1 to not generate a network LSA, and R2 cannot install routes that rely on that LSA.
Why this is correct
R1's point-to-point network type does not elect a DR or generate Type 2 LSAs, so R2 lacks the necessary topology information for transit.
- ✗
The OSPF adjacency is stuck in EXSTART state due to MTU mismatch.
Why it's wrong here
The adjacency is FULL, so MTU is not an issue.
- ✗
R2 has a firewall blocking Type 2 LSAs.
Why it's wrong here
OSPF LSAs are not blocked by firewalls in this context; the issue is protocol behavior.
- ✗
R1's router LSA has an incorrect metric, causing R2 to ignore it.
Why it's wrong here
The metric is not the issue; the LSA type mismatch is.
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 300-410 question from scratch — 1,966 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 300-410 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 300-410 exam.