- A
OSPFv3 will form adjacencies over both interfaces using the configured IPv6 addresses.
Why wrong: Incorrect. OSPFv3 uses link-local addresses for adjacencies, not the global unicast addresses configured.
- B
OSPFv3 will form adjacencies over both interfaces using link-local addresses.
Correct. OSPFv3 always uses link-local addresses for neighbor communication. The global addresses are used for routing.
- C
OSPFv3 will only run on GigabitEthernet0/0 because the router-id is not configured for GigabitEthernet0/1.
Why wrong: Incorrect. The router-id is a global OSPFv3 parameter, not per-interface.
- D
OSPFv3 requires an explicit network command under the OSPFv3 process to enable on interfaces.
Why wrong: Incorrect. OSPFv3 is enabled directly on the interface with 'ipv6 ospf' command; there is no network command in OSPFv3.
Quick Answer
The answer is that OSPFv3 will form adjacencies over both interfaces using link-local addresses. This is because OSPFv3 operates on a per-interface basis and inherently uses IPv6 link-local addresses for neighbor discovery and next-hop forwarding, unlike OSPFv2 which relies on the configured IPv4 address. In the configuration, both GigabitEthernet interfaces have the `ipv6 ospf 1 area 0` command, which activates OSPFv3 on those links, and the router-id 2.2.2.2 is correctly set and unique, satisfying the mandatory requirement for OSPFv3 operation. On the ENCOR 350-401 exam, this concept tests your understanding that OSPFv3 does not use the global unicast IPv6 addresses shown in the config for forming neighbors; a common trap is assuming OSPFv3 behaves exactly like OSPFv2. Remember the memory tip: OSPFv3 uses link-local for neighbors, global for routes.
350-401 REST APIs and Data Models Practice Question
This 350-401 practice question tests your understanding of rest apis and data models. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Examine the following configuration for a Cisco IOS-XE device:
interface GigabitEthernet0/0 ip address 10.0.0.1 255.255.255.252
ipv6 address 2001:db8::1/64 ipv6 ospf 1 area 0 !
interface GigabitEthernet0/1 ip address 192.168.1.1 255.255.255.0
ipv6 address 2001:db8:1::1/64 ipv6 ospf 1 area 0 ! ipv6 router ospf 1 router-id 2.2.2.2
Which statement is true about OSPFv3 operation?
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
OSPFv3 will form adjacencies over both interfaces using link-local addresses.
OSPFv3 runs per interface and uses link-local addresses for neighbor discovery. The router-id is required and must be unique. Both interfaces are in area 0.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
OSPFv3 will form adjacencies over both interfaces using the configured IPv6 addresses.
Why it's wrong here
Incorrect. OSPFv3 uses link-local addresses for adjacencies, not the global unicast addresses configured.
- ✓
OSPFv3 will form adjacencies over both interfaces using link-local addresses.
Why this is correct
Correct. OSPFv3 always uses link-local addresses for neighbor communication. The global addresses are used for routing.
Related concept
OSPF neighbours must agree on key parameters.
- ✗
OSPFv3 will only run on GigabitEthernet0/0 because the router-id is not configured for GigabitEthernet0/1.
Why it's wrong here
Incorrect. The router-id is a global OSPFv3 parameter, not per-interface.
- ✗
OSPFv3 requires an explicit network command under the OSPFv3 process to enable on interfaces.
Why it's wrong here
Incorrect. OSPFv3 is enabled directly on the interface with 'ipv6 ospf' command; there is no network command in OSPFv3.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Trap categories for this question
Command / output trap
Incorrect. OSPFv3 is enabled directly on the interface with 'ipv6 ospf' command; there is no network command in OSPFv3.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
- OSPF neighbours must agree on key parameters.
- Router ID selection can affect neighbour relationships and LSDB output.
- OSPF cost influences the preferred path.
- A route can appear in OSPF information but not become the installed route.
TExam Day Tips
- Check area mismatch first when OSPF adjacency fails.
- Review passive interfaces when a network is advertised but no neighbour forms.
- Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
What to study next
Got this wrong? Here's your next step.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
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FAQ
Questions learners often ask
What does this 350-401 question test?
REST APIs and Data Models — This question tests REST APIs and Data Models — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: OSPFv3 will form adjacencies over both interfaces using link-local addresses. — OSPFv3 runs per interface and uses link-local addresses for neighbor discovery. The router-id is required and must be unique. Both interfaces are in area 0.
What should I do if I get this 350-401 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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Last reviewed: Jun 18, 2026
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.
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