mediumMultiple Choice
350-401 Practice Question: Runs the following command on Router R9: R9# show…
A network engineer runs the following command on Router R9:
R9# show ip ospf interface brief Interface PID Area IP Address/Mask Cost State Nbrs F/C
Gi0/0 1 0 192.168.1.9/24 10 DR 2/2 Gi0/1 1 1 10.0.0.9/24 20 BDR 1/1 Lo0 1 0 9.9.9.9/32 1 LOOP 0/0
Based on this output, what can be concluded?
⚠ Common exam trap
Cisco often tests the misinterpretation of the 'Nbrs F/C' field, where candidates confuse the total neighbor count with the number of fully adjacent neighbors, or assume that being in the DR state on one interface implies DR status on all interfaces.
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
✓
R9 has two fully adjacent neighbors on Gi0/0.
The output shows that on interface Gi0/0, R9 has a state of DR (Designated Router) and 2 fully adjacent neighbors (Nbrs F/C = 2/2). The '2/2' indicates 2 neighbors in a full state out of 2 total neighbors, meaning both neighbors have completed the OSPF adjacency process. Therefore, R9 has two fully adjacent neighbors on Gi0/0, making option B correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
R9 is the Designated Router on the segment connected to Gi0/1.
Why it's wrong here
R9 cannot be the Designated Router (DR) on the segment connected to Gi0/1 because the output shows 'State: BDR' for that interface. In OSPF, the BDR is the backup to the DR and does not initiate the flooding of updates on the segment. The DR for that link would be indicated by the state 'DR' on the interface or by the 'designated router' field in the neighbor table, neither of which applies to R9. Therefore, this statement is incorrect.
- ✓
R9 has two fully adjacent neighbors on Gi0/0.
Why this is correct
The 'Nbrs F/C' column for Gi0/0, which stands for Fully adjacent neighbors / Count of all neighbors, displays 2/2. This means that R9 has exactly two neighbors on that interface, and both have reached the 'Full' state, indicating fully adjacent neighbors with synchronized link-state databases. Therefore, the statement that R9 has two fully adjacent neighbors on Gi0/0 is a factual conclusion directly supported by the output.
- ✗
The loopback interface Lo0 is advertised as a /24 network.
Why it's wrong here
The loopback interface Lo0 is listed with IP address 9.9.9.9/32, meaning the configured subnet mask is 255.255.255.255. OSPF advertises the interface's actual prefix mask, so Lo0 will be injected into the OSPF domain as a /32 host route, not as a /24 network. A /24 advertisement would require a 255.255.255.0 mask on that interface, which is not the case. Hence, the statement that the loopback is advertised as a /24 network is incorrect.
- ✗
R9 is an Area Border Router.
Why it's wrong here
Having interfaces in area 0 and area 1 makes it an ABR, but the output does not explicitly state that; however, the question asks what can be concluded from the output, and the neighbor counts are correct.
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 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.