300-410 Layer 3 Technologies Practice Question
A network engineer is configuring OSPFv3 on a router that connects to an IPv6 network. The router must form an adjacency with a neighbor on the same segment, but the engineer notices that the router is not sending any OSPFv3 Hello packets. The interface is up, and IPv6 unicast routing is enabled globally. Which of the following is the most likely cause?
⚠ Common exam trap
The trap here is assuming that enabling IPv6 unicast routing and creating an OSPFv3 process automatically enables OSPFv3 on all interfaces, as OSPFv2 does with network statements.
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 OSPFv3 process is not enabled on the interface.
For OSPFv3 to operate on an interface, the interface must be explicitly enabled for OSPFv3 using the 'ipv6 ospf' command under interface configuration. Simply enabling IPv6 unicast routing and configuring an OSPFv3 process is not sufficient. Without interface enablement, no Hello packets are sent, and no adjacency can form. This is a common oversight when transitioning from OSPFv2, where network statements are used.
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 OSPFv3 process is not enabled on the interface.
Why this is correct
OSPFv3 requires that the interface be explicitly enabled for OSPFv3 using the 'ipv6 ospf <process-id> area <area-id>' interface configuration command. Without this, the router will not send Hello packets on that interface even if the OSPFv3 process is running. Other options are incorrect because they either do not prevent Hello generation or are not applicable.
- ✗
The interface is configured as passive.
Why it's wrong here
A passive interface in OSPFv3 suppresses Hello packets on that interface, which would prevent adjacency formation. However, the question indicates that the router is not sending any Hello packets; if the interface were passive, it would still be included in the OSPFv3 domain but would not form adjacencies. The more fundamental issue is that the interface is not enabled for OSPFv3 at all.
- ✗
The OSPFv3 network type is set to point-to-multipoint.
Why it's wrong here
Changing the OSPFv3 network type to point-to-multipoint does not prevent Hello packets; it actually changes the Hello behavior but still sends Hellos. In fact, point-to-multipoint networks send Hellos as unicast, but they are still sent. This would not cause a complete absence of Hello packets, so it is not the most likely cause.
- ✗
The OSPFv3 router ID is not configured.
Why it's wrong here
If the OSPFv3 router ID is not explicitly configured, the router will attempt to derive one from an IPv4 address on a loopback or physical interface. If no IPv4 address exists, OSPFv3 will not start, but the symptom would be that the OSPFv3 process does not run at all, not that the interface is not sending Hellos. The question states that IPv6 unicast routing is enabled, and no mention of router ID issues.
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.