Question 565 of 2,152
OSPF Troubleshooting (v2/v3)hardMultiple SelectObjective-mapped

300-410 OSPF Troubleshooting (v2/v3) Practice Question

This 300-410 practice question tests your understanding of ospf troubleshooting (v2/v3). 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.

Which THREE symptoms indicate a potential OSPFv2 neighbor adjacency problem due to a mismatch in configuration? (Choose THREE.)

Question 1hardmulti select
Review the full OSPF breakdown →

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 neighbor state remains stuck in INIT or EXSTART.

A mismatch in hello/dead timers, area ID, or authentication causes neighbors to stay stuck in INIT or EXSTART state. A mismatched MTU can cause stuck in EXSTART/EXCHANGE. A mismatched network type can also cause issues. Routes missing from the routing table is a symptom of many issues, not specific to mismatches.

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 state remains stuck in INIT or EXSTART.

    Why this is correct

    Mismatched parameters (e.g., timers, area ID) often prevent full adjacency, leaving the state in INIT or EXSTART.

    Related concept

    OSPF neighbours must agree on key parameters.

  • The neighbor state is 2WAY/DROTHER.

    Why it's wrong here

    2WAY/DROTHER is normal for non-DR/BDR routers on broadcast networks.

  • The 'show ip ospf neighbor' output shows the neighbor but with a state of DOWN.

    Why it's wrong here

    A neighbor in DOWN state is not listed in 'show ip ospf neighbor' output.

  • The 'show ip ospf neighbor' output shows the neighbor but with a state of EXSTART/EXCHANGE.

    Why this is correct

    Stuck in EXSTART/EXCHANGE often indicates MTU mismatch or DD packet issues.

    Related concept

    OSPF neighbours must agree on key parameters.

  • The OSPF routes are missing from the routing table.

    Why this is correct

    If adjacency is not FULL, routes are not exchanged, leading to missing OSPF routes.

    Related concept

    OSPF neighbours must agree on key parameters.

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

    A neighbor in DOWN state is not listed in 'show ip ospf neighbor' output.

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 300-410 OSPF questions on adjacency and route selection.

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FAQ

Questions learners often ask

What does this 300-410 question test?

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 state remains stuck in INIT or EXSTART. — A mismatch in hello/dead timers, area ID, or authentication causes neighbors to stay stuck in INIT or EXSTART state. A mismatched MTU can cause stuck in EXSTART/EXCHANGE. A mismatched network type can also cause issues. Routes missing from the routing table is a symptom of many issues, not specific to mismatches.

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.

What is the key concept behind this question?

OSPF neighbours must agree on key parameters.

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Last reviewed: Jun 18, 2026

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