hardMultiple Choice
300-410 Practice Question: Is troubleshooting an OSPFv2 adjacency issue…
A network engineer is troubleshooting an OSPFv2 adjacency issue between two routers across a Frame Relay network. R1 and R2 are connected via a point-to-point subinterface. The engineer configures 'ip ospf network point-to-point' on both subinterfaces. However, the adjacency does not form. 'show ip ospf interface' on R1 shows the interface is up and OSPF is enabled, but no neighbors are seen. What is the most likely cause?
⚠ Common exam trap
The trap here is assuming that because the interface is 'up' and OSPF is enabled, Layer 3 connectivity is functional; candidates often overlook that Frame Relay requires explicit mapping or DLCI assignment for multicast traffic like OSPF hellos to traverse the cloud.
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 Frame Relay map is missing or the DLCI is not assigned to the subinterface.
The most likely cause is that the Frame Relay map is missing or the DLCI is not assigned to the point-to-point subinterface. Even though OSPF is enabled and the interface is up, OSPF hellos are multicast to 224.0.0.5; without a Frame Relay map or a DLCI assignment, those multicast packets cannot be sent across the Frame Relay cloud. Therefore, no OSPF neighbor relationship can form. The other options are either already addressed in the scenario or less likely given the symptoms.
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 is set to broadcast, causing a DR/BDR election that fails on a point-to-point subinterface.
Why it's wrong here
Configuring point-to-point on both subinterfaces removes DR/BDR election entirely, so broadcast cannot be the state shown. The engineer already applied the command; the stem confirms OSPF is enabled. Broadcast network type is the default on multipoint Frame Relay interfaces, where DR/BDR election is genuinely required.
- ✗
The subinterface is not configured with an IP address.
Why it's wrong here
An unaddressed subinterface cannot form an OSPF adjacency, but the stem states the interface is up with OSPF enabled, which requires an IP address. The likely cause is a mismatched OSPF network type or area, or hello/MTU mismatch. Missing IP addressing is tempting as a basic check, yet it contradicts the stated interface state.
- ✓
The Frame Relay map is missing or the DLCI is not assigned to the subinterface.
Why this is correct
OSPF point-to-point mode still relies on Frame Relay Layer 2 reachability. Without a frame-relay map or DLCI assigned to the subinterface, hellos cannot traverse the PVC, so the adjacency never forms despite OSPF being enabled.
- ✗
The OSPF hello and dead timers are mismatched between R1 and R2.
Why it's wrong here
Mismatched hello/dead timers would prevent adjacency, but the stem gives no evidence of timer configuration differences, and default values match on both routers. Timer mismatch is the classic cause when one side is tuned for faster convergence, such as reducing hello to 5 seconds on a point-to-point link.
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 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 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.