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350-401 OSPF Practice Question

This 350-401 practice question tests your understanding of ospf. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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.

Drag and drop the steps of OSPF SPF calculation steps (Dijkstra) into the correct order, from first to last.

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.

Question 1mediumdrag order

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

✓

Initialize candidate list with root router

The Dijkstra SPF algorithm first initializes the candidate list with the root router itself. It then examines the root's neighbors, adding them to the candidate list. The router with the lowest cost is moved from candidate to the SPF tree. The process repeats by examining the newly added router's neighbors and updating the candidate list. Finally, when all routers are in the SPF tree, the algorithm terminates and the routing table is populated.

Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.

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 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?

OSPF — This question tests OSPF — OSPF neighbours must agree on key parameters..

What is the correct answer to this question?

The correct answer is: Initialize candidate list with root router — The Dijkstra SPF algorithm first initializes the candidate list with the root router itself. It then examines the root's neighbors, adding them to the candidate list. The router with the lowest cost is moved from candidate to the SPF tree. The process repeats by examining the newly added router's neighbors and updating the candidate list. Finally, when all routers are in the SPF tree, the algorithm terminates and the routing table is populated.

What should I do if I get this 350-401 question wrong?

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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