Question 19 of 2,152
EIGRP TroubleshootinghardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the offset-list was applied under `af-interface` instead of `address-family`, so it modifies the advertised distance (AD) sent to neighbors, not the feasible distance (FD). In EIGRP named mode, the configuration context determines what the offset-list targets: when placed under `af-interface`, it adjusts the metric in outgoing updates, increasing the AD that neighbors receive, while the local router’s FD remains unchanged. To affect the FD, the offset-list must be applied under the `address-family` section using the `offset-list <acl> {in|out} <metric>` command. This distinction is a common trap on the Cisco CCNP ENARSI 300-410 exam, testing your understanding of named mode’s hierarchical structure versus classic mode, where offset-lists always impact the FD for incoming updates. A helpful memory tip: “AF-interface adjusts AD outward; address-family fixes FD inward.”

300-410 EIGRP Troubleshooting Practice Question

This 300-410 practice question tests your understanding of eigrp troubleshooting. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.

An engineer configures EIGRP named mode with `address-family ipv4 unicast autonomous-system 100` and applies an offset-list to a neighbor using `offset-list 1 out 1000` under the `af-interface` configuration. Unexpectedly, the offset-list does not affect the feasible distance (FD) as expected, but the advertised distance (AD) is increased. Which is the most likely explanation?

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.

Question 1hardmultiple choice
Study the full EIGRP explanation →

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 offset-list was applied under `af-interface` instead of `address-family`, so it modifies the AD sent to neighbors, not the FD.

In EIGRP named mode, offset-lists applied under the `af-interface` affect only the AD (the metric sent to neighbors), not the FD. To affect the FD, the offset-list must be applied under the `address-family` section using `offset-list <acl> {in|out} <metric>`. This is a subtle difference from classic mode where offset-lists always affect the FD for incoming updates.

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 offset-list was applied under `af-interface` instead of `address-family`, so it modifies the AD sent to neighbors, not the FD.

    Why this is correct

    Named mode separates interface-specific and address-family-level offset-lists; only the latter adjusts FD.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    OSPF neighbours must agree on key parameters.

  • The offset-list command is not supported in named mode; it must be replaced with a route-map to adjust metrics.

    Why it's wrong here

    Offset-list is supported in named mode but with different placement.

  • The offset-list was applied outbound, which only affects the AD; inbound offset-lists affect the FD.

    Why it's wrong here

    Both inbound and outbound offset-lists affect FD in classic mode, but in named mode the placement matters.

  • The offset-list value of 1000 is too high and causes the route to be suppressed, so FD is not updated.

    Why it's wrong here

    High offset values do not suppress routes; they only increase metric.

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 300-410 OSPF questions on adjacency and route selection.

Related practice questions

Related 300-410 practice-question pages

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FAQ

Questions learners often ask

What does this 300-410 question test?

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

What is the correct answer to this question?

The correct answer is: The offset-list was applied under `af-interface` instead of `address-family`, so it modifies the AD sent to neighbors, not the FD. — In EIGRP named mode, offset-lists applied under the `af-interface` affect only the AD (the metric sent to neighbors), not the FD. To affect the FD, the offset-list must be applied under the `address-family` section using `offset-list <acl> {in|out} <metric>`. This is a subtle difference from classic mode where offset-lists always affect the FD for incoming updates.

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: "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.

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Last reviewed: Jun 18, 2026

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