300-410 Layer 3 Technologies Practice Question
A network engineer is configuring OSPFv3 on a Cisco router. The router has two interfaces in Area 0: GigabitEthernet0/0 (IPv6 address 2001:db8:1::1/64) and GigabitEthernet0/1 (IPv6 address 2001:db8:2::1/64). After enabling IPv6 unicast routing and configuring OSPFv3 with the router-id 1.1.1.1, the engineer notices that no OSPFv3 neighbors are forming. Which action is most likely to resolve the issue?
⚠ Common exam trap
The trap here is assuming that OSPFv3 is enabled globally under router configuration like OSPFv2, when in fact it must be enabled per interface.
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
✓
Enable OSPFv3 on the interfaces using the ipv6 ospf 1 area 0 command.
OSPFv3 requires enabling the protocol on each interface using the ipv6 ospf process-id area area-id command. Without this, the interface does not participate in OSPFv3, and no hellos are sent or received. The router ID and network type are secondary. Assigning IPv6 addresses from the same subnet is irrelevant because OSPFv3 uses link-local addresses for neighbor discovery.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Assign IPv6 addresses from the same subnet to both interfaces.
Why it's wrong here
OSPFv3 neighbors can form over interfaces with different IPv6 subnets because OSPFv3 uses link-local addresses for neighbor communication. Assigning the same subnet is not required and would actually cause addressing conflicts if the interfaces are on different links. The real issue is that OSPFv3 is not enabled on the interfaces, so no OSPFv3 packets are exchanged.
- ✓
Enable OSPFv3 on the interfaces using the ipv6 ospf 1 area 0 command.
Why this is correct
OSPFv3 is enabled per interface, unlike OSPFv2 which can be enabled under router configuration. Without the ipv6 ospf 1 area 0 interface command, the interfaces do not participate in OSPFv3, so no hellos are sent or received. This command activates OSPFv3 on the interface and associates it with Area 0. Thus, neighbors will form once the interfaces are enabled.
- ✗
Set the OSPFv3 network type to point-to-point on both interfaces.
Why it's wrong here
Changing the network type to point-to-point can affect neighbor formation on broadcast networks, but it is not the primary issue here. The interfaces are not enabled for OSPFv3 at all, so no hellos are sent regardless of network type. Point-to-point is useful for eliminating DR/BDR elections on links with only two routers, but it does not enable OSPFv3 on an interface.
- ✗
Configure a 64-bit router ID using the router-id command under the OSPFv3 process.
Why it's wrong here
OSPFv3 router ID is still a 32-bit value in dotted-decimal format, just like OSPFv2. Configuring a 64-bit router ID is not supported and would be rejected. The router ID must be unique and can be set manually, but it does not affect neighbor formation on interfaces that are not enabled for OSPFv3. The problem is interface enablement, not router ID format.
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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JA
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.