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 1,368 of 1,052
hardmultiple choiceObjective-mapped
CCNA Practice Question: Is troubleshooting an OSPFv3 adjacency issue…
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 ipv6 ospf neighbor
Neighbor ID Pri State Dead Time Interface ID Interface
192.168.1.2 1 EXSTART/DR 00:00:32 2 GigabitEthernet0/0
R1# show ipv6 ospf interface gigabitethernet0/0
GigabitEthernet0/0 is up, line protocol is up
Link Local Address FE80::1, Interface ID 2
Area 0, Process ID 1, Router ID 192.168.1.1, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID) 192.168.1.1, local address FE80::1
Backup Designated router (ID) 192.168.1.2, local address FE80::2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:07
Index 1/1/1, flood queue length 0
Next 0x0(0)/0x0(0)/0x0(0)
Last flood scan length is 0, maximum is 0
Neighbor Count is 1, Adjacent neighbor count is 0
Adjacent with neighbor 192.168.1.2 (Backup Designated Router)
Suppress hello for 0 neighbor(s)
R1# show ipv6 route ospf
<no output>A network engineer is troubleshooting an OSPFv3 adjacency issue between two directly connected routers. Both routers are configured for OSPFv3 in area 0 on their GigabitEthernet0/0 interfaces. The engineer checks the OSPFv3 neighbor status on R1 and sees that the neighbor state is stuck in EXSTART. The engineer verifies that both interfaces are up and have IPv6 link-local addresses. What is the most likely cause of this problem?
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
✓
Ensure that the MTU is the same on both sides of the link.
The OSPFv3 adjacency is stuck in EXSTART state, which indicates a problem during the database description (DBD) packet exchange. Since both routers have IPv6 link-local addresses and are in the same area, the most common cause is an MTU mismatch. The MTU mismatch prevents DBD packets from being exchanged properly. The correct solution is to ensure the MTU is consistent on both interfaces. Option B is correct because it addresses the MTU issue. Option A is incorrect because OSPFv3 uses IPv6 link-local addresses by default and does not require global unicast addresses. Option C is incorrect because the router IDs are different (192.168.1.1 and 192.168.1.2). Option D is incorrect because OSPFv3 can form adjacencies over a broadcast network with default settings; the issue is not related to network type.
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.
- ✗
Configure a global unicast IPv6 address on the interface.
Why it's wrong here
OSPFv3 uses link-local addresses for neighbor discovery and does not require global unicast addresses.
- ✓
Ensure that the MTU is the same on both sides of the link.
- ✗
Change the router ID to be the same on both routers.
- ✗
Change the network type to point-to-point.
Why it's wrong here
OSPFv3 can form adjacencies over broadcast networks with default settings; changing network type is not necessary.
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.
✓Ensure that the MTU is the same on both sides of the link.Correct answer▾
Why this is correct
An MTU mismatch can cause OSPFv3 to get stuck in EXSTART state because DBD packets exceed the MTU of one interface.
✗Configure a global unicast IPv6 address on the interface.Wrong answer — click to see why▾
Why this is wrong here
The problem is not due to missing global addresses; the adjacency is stuck at EXSTART, not at DOWN or INIT.
✗Change the router ID to be the same on both routers.Wrong answer — click to see why▾
Why this is wrong here
The show output shows different router IDs (192.168.1.1 and 192.168.1.2), so this is not the issue.
✗Change the network type to point-to-point.Wrong answer — click to see why▾
Why this is wrong here
The adjacency is stuck in EXSTART, which is not typically resolved by changing network type; the issue is related to packet exchange.
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.
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: Ensure that the MTU is the same on both sides of the link. — The OSPFv3 adjacency is stuck in EXSTART state, which indicates a problem during the database description (DBD) packet exchange. Since both routers have IPv6 link-local addresses and are in the same area, the most common cause is an MTU mismatch. The MTU mismatch prevents DBD packets from being exchanged properly. The correct solution is to ensure the MTU is consistent on both interfaces. Option B is correct because it addresses the MTU issue. Option A is incorrect because OSPFv3 uses IPv6 link-local addresses by default and does not require global unicast addresses. Option C is incorrect because the router IDs are different (192.168.1.1 and 192.168.1.2). Option D is incorrect because OSPFv3 can form adjacencies over a broadcast network with default settings; the issue is not related to network type.
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.