mediumMultiple Choice
300-410 OSPF neighbor states Practice Question
A network engineer runs the following command on Router R1:
R1# show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 192.168.1.2 1 FULL/DR 00:00:35 10.1.1.2 GigabitEthernet0/0 192.168.2.2 1 2WAY/DROTHER 00:00:32 10.2.2.2 GigabitEthernet0/1 192.168.3.2 1 FULL/BDR 00:00:38 10.3.3.2 GigabitEthernet0/2
Based on this output, what is a potential issue?
⚠ Common exam trap
Candidates often incorrectly assume that any state other than FULL indicates a problem. However, in OSPF broadcast multi-access networks, the 2WAY state between DROTHER routers is normal and does not indicate an issue.
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
✓
All neighbors are in FULL state, indicating no issues.
The output shows normal OSPF neighbor states on a broadcast multi-access network. The neighbor on Gi0/1 is in the 2WAY/DROTHER state, which is expected for non-DR/BDR routers. The neighbors on Gi0/0 and Gi0/2 are in FULL state (DR and BDR respectively). All states are valid, so there is no issue.
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 neighbor on Gi0/1 is not forming a full adjacency because it is in 2WAY state.
Why it's wrong here
2WAY/DROTHER is the expected state between non-DR/BDR routers on a broadcast segment; full adjacency forms only with the DR and BDR. It tempts because 2WAY on a point-to-point link would indicate a genuine adjacency failure, so the state looks alarming without checking network type.
- ✗
The neighbor on Gi0/0 is the DR, which is causing high CPU usage.
Why it's wrong here
DR status on Gi0/0 is normal and does not by itself cause high CPU; DR election follows priority and router ID. It tempts because a flapping DR can trigger repeated SPF recalculations and CPU spikes, so linking DR behaviour to CPU load is reasonable when instability is observed.
- ✗
The neighbor on Gi0/2 is the BDR, which is a problem because it should be the DR.
Why it's wrong here
A BDR on Gi0/2 is normal; DR/BDR election depends on priority and router ID, and any non-DR router legitimately becomes BDR. It tempts because DR/BDR roles are frequently misconfigured, so checking which router holds which role is a sensible troubleshooting step when adjacency problems appear.
- ✓
All neighbors are in FULL state, indicating no issues.
Why this is correct
The 2WAY/DROTHER state on GigabitEthernet0/1 is normal for a non-DR/BDR router on a broadcast segment, so no adjacency fault exists; the two FULL adjacencies confirm working OSPF relationships, meaning the output shows no actual problem.
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.
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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.