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300-410 EIGRP Active State Practice Question

This 300-410 practice question tests your understanding of mpls operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: eIGRP Active State. 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.

EIGRP stuck-in-active (SIA) occurs in a large network. Router R1 shows 'show ip eigrp topology 10.0.0.0/24' output: 'P 10.0.0.0/24, 1 successors, FD is 128000, Q is 0, SIA is 00:01:00' and 'show ip eigrp neighbors' shows neighbor R2 in state 'Active'. R1 configuration includes 'router eigrp 100 network 10.0.0.0 passive-interface default'. What is the root cause?

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

R1 has a route-map that filters the query for prefix 10.0.0.0/24.

EIGRP SIA occurs when a router does not receive a reply to its query within the active timer. The scenario shows R1 has a neighbor R2 in Active state, but R1's configuration includes 'passive-interface default', which would normally prevent neighbor formation. Since the neighbor exists, the passive-interface default is likely overridden or not affecting the interface to R2. Option B is the most plausible cause: R1 has a route-map that filters the query for prefix 10.0.0.0/24, preventing the query from being sent to R2. Without receiving the query, R2 cannot reply, leading to SIA.

Key principle: EIGRP Active State

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • R2 has 'passive-interface default' configured, which prevents it from sending query replies back to R1.

    Why it's wrong here

    Incorrect. The scenario states R1 has passive-interface default, not R2. Additionally, passive-interface on R1 would prevent neighbor formation, not cause an Active state neighbor.

  • R1 has a route-map that filters the query for prefix 10.0.0.0/24.

    Why this is correct

    Correct. A route-map filtering the specific prefix 10.0.0.0/24 can block the query from being sent to R2, so R2 never replies, causing SIA.

    Related concept

    EIGRP Active State

  • The EIGRP K-values mismatch between R1 and R2 causes neighbor relationship issues.

    Why it's wrong here

    Incorrect. K-values mismatch would prevent the EIGRP neighbor relationship from forming at all, but here the neighbor exists.

  • The network 10.0.0.0 is not directly connected; need redistribution.

    Why it's wrong here

    Incorrect. The network command under EIGRP includes 10.0.0.0/24, so no redistribution is needed. This does not cause SIA.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Passive-interface is often blamed for SIA, but here the actual cause is a distribute-list or route-map that filters the specific query. Ensure you check for route filtering when neighbors exist and SIA occurs.

Trap categories for this question

  • Command / output trap

    Incorrect. The network command under EIGRP includes 10.0.0.0/24, so no redistribution is needed. This does not cause SIA.

  • Scenario analysis trap

    Incorrect. The scenario states R1 has passive-interface default, not R2. Additionally, passive-interface on R1 would prevent neighbor formation, not cause an Active state neighbor.

Detailed technical explanation

How to think about this question

Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.

KKey Concepts to Remember

  • EIGRP Active State
  • Distribute-list
  • Stuck-in-Active (SIA)

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

EIGRP Active State

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.

Quick reference

Routing Protocol Comparison

ProtocolMetricMax HopsAlgorithmType
RIP v2Hop count15Bellman-FordDistance vector
OSPFCost (bandwidth)UnlimitedDijkstra (SPF)Link state
EIGRPComposite metricUnlimitedDUALHybrid
IS-ISCostUnlimitedDijkstraLink state
BGPPolicy / attributesUnlimitedPath vectorPath vector

RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.

What to study next

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FAQ

Questions learners often ask

What does this 300-410 question test?

MPLS Operations — This question tests MPLS Operations — EIGRP Active State.

What is the correct answer to this question?

The correct answer is: R1 has a route-map that filters the query for prefix 10.0.0.0/24. — EIGRP SIA occurs when a router does not receive a reply to its query within the active timer. The scenario shows R1 has a neighbor R2 in Active state, but R1's configuration includes 'passive-interface default', which would normally prevent neighbor formation. Since the neighbor exists, the passive-interface default is likely overridden or not affecting the interface to R2. Option B is the most plausible cause: R1 has a route-map that filters the query for prefix 10.0.0.0/24, preventing the query from being sent to R2. Without receiving the query, R2 cannot reply, leading to SIA.

What should I do if I get this 300-410 question wrong?

Review eIGRP Active State, then practise related 300-410 questions on the same topic to reinforce the concept.

What is the key concept behind this question?

EIGRP Active State

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Last reviewed: Jun 18, 2026

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