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300-410 An engineer configures OSPFv3 on two routers Practice Question
An engineer configures OSPFv3 on two routers. Both routers are in the same area, but they fail to form an adjacency. Which is the most likely explanation?
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 link-local addresses on the interfaces are not configured.
OSPFv3 uses link-local addresses for neighbor adjacencies. If the link-local addresses are not configured or are in the same subnet, OSPFv3 will not form an adjacency because it cannot determine the next hop for routing updates.
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 link-local addresses on the interfaces are not configured.
Why this is correct
OSPFv3 requires link-local addresses to form adjacencies; without them, the routers cannot communicate.
- ✗
The OSPFv3 process is not enabled with an IPv6 unicast address-family.
Why it's wrong here
OSPFv3 requires an address-family, but this would not prevent adjacency formation if link-local addresses are present.
- ✗
The routers are using different OSPFv3 router IDs.
Why it's wrong here
Different router IDs are normal and do not prevent adjacency.
- ✗
The OSPFv3 network type is set to broadcast on both routers.
Why it's wrong here
Broadcast network type is common and does not prevent adjacency.
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.