The answer is that the neighbor is stuck in the 2WAY state, which means the OSPF adjacency has not progressed to FULL. On a broadcast multiaccess network, the 2WAY state is normal for non-designated router (DR) and non-backup designated router (BDR) neighbors, but if a router expects to form a full adjacency—such as between a DR and BDR—this state indicates a failure in the database exchange process. For the Cisco CCNP ENARSI 300-410 exam, this output tests your ability to interpret the *show ip ospf neighbor detail* command and recognize that a state other than FULL or DROTHER signals a problem, often caused by mismatched MTU, authentication, or a silent interface misconfiguration. A common trap is assuming 2WAY is always an error, but remember: on a broadcast segment, only the DR and BDR should reach FULL; all other neighbor pairs remain in 2WAY. Memory tip: “2WAY means hello, but no database play”—if you see it where FULL is expected, check your MTU and authentication settings first.
300-410 OSPF Troubleshooting (v2/v3) Practice Question
This 300-410 practice question tests your understanding of ospf troubleshooting (v2/v3). Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A network engineer runs the following command on Router R1:
R1# show ip ospf neighbor detail
Neighbor 10.1.1.4, interface address 192.168.14.4
In the area 0 via interface GigabitEthernet0/2
Neighbor priority is 1, State is 2WAY, 2 state changes
DR is 10.1.1.1, BDR is 10.1.1.4
Options is 0x12 (L L S R)
Dead timer due in 00:00:38
Neighbor is up for 00:05:22
Index 1/1/1, retransmission queue length 0, number of retransmission 0
First 0x0(0)/0x0(0) Next 0x0(0)/0x0(0)
Last retransmission scan length is 0, time is 0 msec
Last retransmission scan time is 0 msec
Based on this output, what is the problem?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The neighbor is in 2WAY state, meaning the adjacency is not fully established.
The neighbor state is 2WAY, not FULL. This indicates that the neighbor relationship has not progressed to full adjacency. On a broadcast network, routers in 2WAY state have exchanged hello packets but have not completed database exchange. This could be due to mismatched MTU, authentication, or other issues, but the key observation is that the state is not FULL.
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 neighbor is in 2WAY state, meaning the adjacency is not fully established.
Why this is correct
2WAY state indicates that the routers have seen each other's hello packets but have not exchanged LSAs. FULL is required for complete adjacency.
Clue confirmation
The clue word "first" in the question point toward this answer.
Router R1 is the DR and the neighbor is the BDR, so the state is correct.
Why it's wrong here
Even if R1 is DR and neighbor is BDR, they should still form a FULL adjacency, not 2WAY.
✗
The dead timer is about to expire, causing the neighbor to go down.
Why it's wrong here
Dead timer is 00:00:38, which is not near zero.
✗
The neighbor has a lower priority than R1, so it remains in 2WAY.
Why it's wrong here
Priority does not affect the state progression beyond 2WAY; all routers should go to FULL with DR/BDR.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
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 300-410 OSPF questions on adjacency and route selection.
OSPF Troubleshooting (v2/v3) — This question tests OSPF Troubleshooting (v2/v3) — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The neighbor is in 2WAY state, meaning the adjacency is not fully established. — The neighbor state is 2WAY, not FULL. This indicates that the neighbor relationship has not progressed to full adjacency. On a broadcast network, routers in 2WAY state have exchanged hello packets but have not completed database exchange. This could be due to mismatched MTU, authentication, or other issues, but the key observation is that the state is not FULL.
What should I do if I get this 300-410 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 300-410 OSPF questions on adjacency and route selection.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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