Question 1hardmultiple choice
Full question →- → Why each wrong option is wrong in this specific scenario
- → When each wrong option would be correct
- → Real-world analogy and exam trap analysis
- → Related glossary terms and similar practice questions
Question 1,501 of 1,052
hardmultiple choiceObjective-mapped
CCNA Practice Question: Is troubleshooting OSPFv3 adjacency between two…
This 200-301 practice question tests your understanding of 200-301 exam topics. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
Exhibit
R1# show ospfv3 neighbor
OSPFv3 1 address-family ipv6 (router-id 1.1.1.1)
Neighbor ID Pri State Dead Time Interface ID Interface
R1# show ipv6 interface brief
GigabitEthernet0/0 [up/up]
FE80::1
GigabitEthernet0/1 [up/up]
FE80::2
R1# show running-config | section router ospfv3
router ospfv3 1
address-family ipv6
router-id 1.1.1.1
area 0
interface GigabitEthernet0/0
interface GigabitEthernet0/1
R1# show running-config interface GigabitEthernet0/0
interface GigabitEthernet0/0
ipv6 address FE80::1 link-local
ipv6 ospfv3 1 ipv6 area 0
!A network engineer is troubleshooting OSPFv3 adjacency between two directly connected Cisco routers, R1 and R2, both running IOS-XE. The engineer configures OSPFv3 on both routers but notices that the adjacency does not form. The engineer runs 'show ospfv3 neighbor' on R1 and sees no neighbors. What is the most likely cause of this issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 interface GigabitEthernet0/0 is missing the 'ipv6 ospfv3 1 ipv6 area 0' command.
The OSPFv3 adjacency requires that the routers use the same area and that the link-local addresses are used for neighbor discovery. In this case, R1 and R2 have link-local addresses on the same subnet but the OSPFv3 configuration on R1's interface GigabitEthernet0/0 is missing the 'ipv6 ospfv3 1 ipv6 area 0' command, which is necessary to enable OSPFv3 on that interface. The 'show ospfv3 neighbor' output shows no neighbors, indicating that OSPFv3 is not active on the interface. The correct fix is to add the 'ipv6 ospfv3 1 ipv6 area 0' command under the interface configuration.
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.
- ✗
The OSPFv3 process ID must match on both routers.
Why it's wrong here
OSPFv3 process IDs are locally significant and do not need to match for adjacency to form.
- ✓
The interface GigabitEthernet0/0 is missing the 'ipv6 ospfv3 1 ipv6 area 0' command.
Why this is correct
Without this command, OSPFv3 is not enabled on the interface, preventing adjacency formation.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
OSPF neighbours must agree on key parameters.
- ✗
The link-local addresses are not in the same subnet.
Why it's wrong here
Link-local addresses are only used for neighbor discovery and do not require subnet matching; they are always on the same link.
- ✗
The router ID 1.1.1.1 is duplicated on R2.
Why it's wrong here
Duplicate router IDs can cause issues, but the 'show ospfv3 neighbor' output would typically show the neighbor in EXSTART or EXCHANGE state, not missing entirely.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The interface GigabitEthernet0/0 is missing the 'ipv6 ospfv3 1 ipv6 area 0' command.Correct answer▾
Why this is correct
Without this command, OSPFv3 is not enabled on the interface, preventing adjacency formation.
✗The OSPFv3 process ID must match on both routers.Wrong answer — click to see why▾
Why this is wrong here
This is a common misconception; OSPFv3 uses the router ID for neighbor identification, not the process ID.
✗The link-local addresses are not in the same subnet.Wrong answer — click to see why▾
Why this is wrong here
Link-local addresses are automatically configured and do not affect OSPFv3 adjacency as long as they are unique.
✗The router ID 1.1.1.1 is duplicated on R2.Wrong answer — click to see why▾
Why this is wrong here
In this scenario, no neighbors are seen, indicating a more fundamental issue like OSPFv3 not being enabled on the interface.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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
Duplicate router IDs can cause issues, but the 'show ospfv3 neighbor' output would typically show the neighbor in EXSTART or EXCHANGE state, not missing entirely.
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 200-301 OSPF questions on adjacency and route selection.
Related practice questions
Related 200-301 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
CCNA subnetting practice questions
Practise IPv4 subnetting, CIDR, masks, host ranges and subnet selection.
CCNA OSPF practice questions
Practise OSPF neighbours, router IDs, metrics, areas and routing-table interpretation.
CCNA VLAN practice questions
Practise VLANs, access ports, trunks, allowed VLANs and switching scenarios.
CCNA STP practice questions
Practise spanning tree, root bridge election, port roles and STP troubleshooting.
CCNA EtherChannel practice questions
Practise LACP, PAgP, port-channel behaviour and bundle requirements.
CCNA ACL practice questions
Practise standard and extended ACLs, permit/deny logic and traffic filtering.
CCNA NAT practice questions
Practise static NAT, dynamic NAT, PAT and inside/outside address translation.
CCNA DHCP practice questions
Practise DHCP scopes, relay, leases and troubleshooting.
CCNA show ip route practice questions
Practise routing-table output, longest-prefix match, AD and route selection.
CCNA show interfaces trunk practice questions
Practise trunk verification and VLAN forwarding across switches.
CCNA wireless security practice questions
Practise WLAN security, authentication and wireless architecture concepts.
CCNA IPv6 practice questions
Practise IPv6 addressing, routes, neighbour discovery and common IPv6 exam traps.
Practice this exam
Start a free 200-301 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this 200-301 question test?
OSPF neighbours must agree on key parameters.
What is the correct answer to this question?
The correct answer is: The interface GigabitEthernet0/0 is missing the 'ipv6 ospfv3 1 ipv6 area 0' command. — The OSPFv3 adjacency requires that the routers use the same area and that the link-local addresses are used for neighbor discovery. In this case, R1 and R2 have link-local addresses on the same subnet but the OSPFv3 configuration on R1's interface GigabitEthernet0/0 is missing the 'ipv6 ospfv3 1 ipv6 area 0' command, which is necessary to enable OSPFv3 on that interface. The 'show ospfv3 neighbor' output shows no neighbors, indicating that OSPFv3 is not active on the interface. The correct fix is to add the 'ipv6 ospfv3 1 ipv6 area 0' command under the interface configuration.
What should I do if I get this 200-301 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 200-301 OSPF questions on adjacency and route selection.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
More 200-301 practice questions
- A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that w…
- A switch has DHCP snooping enabled, but users still experience IP-to-MAC spoofing attacks. Which additional feature shou…
- Switch SW1 sends traffic for VLAN 30 across a trunk to SW2, but hosts in VLAN 30 on SW2 cannot communicate with hosts in…
- What problem is HSRP designed to solve?
- Which DHCP message does the client send to formally accept an offered address?
- What metric does RIP use to choose the best path?
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Loading comments…
Sign in to join the discussion.
This 200-301 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 200-301 exam.