Question 2,113 of 2,152
EIGRP TroubleshootingmediumMultiple ChoiceObjective-mapped

Understanding the EIGRP Topology Table with the All-Links Option

This 300-410 practice question tests your understanding of eigrp troubleshooting. 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 eigrp topology all-links

EIGRP-IPv4 Topology Table for AS(100)/ID(192.168.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status

P 10.10.10.0/24, 1 successors, FD is 28160, Qos: 0 via 10.1.1.2 (28160/28160), GigabitEthernet0/0 via 10.2.2.2 (28672/28160), GigabitEthernet0/1 P 10.20.20.0/24, 1 successors, FD is 28160, Qos: 0 via 10.2.2.2 (28160/28160), GigabitEthernet0/1 via 10.3.3.2 (28672/28160), GigabitEthernet0/2

Based on this output, which statement is correct?

Quick Answer

The answer is that the network has redundant paths with feasible successors for both routes. This is correct because the all-links option in the EIGRP topology table reveals every known path, including those that meet the feasibility condition—where the reported distance from a neighbor is strictly less than the feasible distance (FD) of the successor. For 10.10.10.0/24, the route via 10.2.2.2 has a reported distance of 28160, which equals the FD of 28160, satisfying the condition and making it a feasible successor; similarly, for 10.20.20.0/24, the route via 10.3.3.2 qualifies. On the Cisco CCNP ENARSI 300-410 exam, this command tests your ability to distinguish between successors and feasible successors, a common trap being that the all-links output does not automatically mean all routes are feasible—you must check the reported distance against the FD. A quick memory tip: “Reported must be less than Feasible to be a Feasible successor.”

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 route to 10.20.20.0/24 has no feasible successor.

Option B is correct. The EIGRP feasibility condition requires the reported distance (RD) to be strictly less than the feasible distance (FD) for a path to be a feasible successor. In the output, for route 10.20.20.0/24, the FD is 28160, and both paths have an RD of 28160, which equals the FD, not less. Therefore, no feasible successor exists for this route. Option A is incorrect because neither route has a feasible successor. Option C is incorrect because the FD for 10.10.10.0/24 is 28160, not 28672. Option D is incorrect because the route is marked 'Passive', not 'Active'.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

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 network has redundant paths with feasible successors for both routes.

    Why it's wrong here

    This statement is incorrect because neither route has a feasible successor. For 10.10.10.0/24, the two paths have RD equal to FD (both 28160), so the second path is not a feasible successor. For 10.20.20.0/24, similarly no feasible successor.

  • The route to 10.20.20.0/24 has no feasible successor.

    Why this is correct

    This is correct. The feasibility condition requires RD < FD. For 10.20.20.0/24, both paths have RD = 28160 equal to FD, so they are not feasible successors. Thus there is no feasible successor.

    Related concept

    Read the scenario before looking for a memorised answer.

  • The FD for 10.10.10.0/24 is 28672.

    Why it's wrong here

    Incorrect. The FD for 10.10.10.0/24 is 28160, not 28672.

  • The route to 10.10.10.0/24 is in Active state.

    Why it's wrong here

    Incorrect. The route is marked 'P' for Passive, not Active.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between the feasible distance (FD) and the metric of alternate paths, leading candidates to confuse the FD value with the composite metric of a non-successor route.

Trap categories for this question

  • Similar concept trap

    This statement is incorrect because neither route has a feasible successor. For 10.10.10.0/24, the two paths have RD equal to FD (both 28160), so the second path is not a feasible successor. For 10.20.20.0/24, similarly no feasible successor.

Detailed technical explanation

How to think about this question

The feasibility condition in EIGRP requires that the reported distance (RD) from a neighbor be strictly less than the feasible distance (FD) for that route; if equal, the neighbor is not a feasible successor. In this output, the RD of 28160 for the second path to 10.20.20.0/24 equals the FD of 28160, which technically violates the strict inequality, but Cisco's implementation allows equality in some cases (e.g., when the path is via a different interface). This nuance is critical when analyzing EIGRP topology tables for loop-free alternate paths.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

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

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A practitioner preparing for the 300-410 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.

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.

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FAQ

Questions learners often ask

What does this 300-410 question test?

EIGRP Troubleshooting — This question tests EIGRP Troubleshooting — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The route to 10.20.20.0/24 has no feasible successor. — Option B is correct. The EIGRP feasibility condition requires the reported distance (RD) to be strictly less than the feasible distance (FD) for a path to be a feasible successor. In the output, for route 10.20.20.0/24, the FD is 28160, and both paths have an RD of 28160, which equals the FD, not less. Therefore, no feasible successor exists for this route. Option A is incorrect because neither route has a feasible successor. Option C is incorrect because the FD for 10.10.10.0/24 is 28160, not 28672. Option D is incorrect because the route is marked 'Passive', not 'Active'.

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

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Same concept, more angles

1 more ways this is tested on 300-410

These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.

Variation 1. A network engineer runs the following command to troubleshoot an EIGRP issue: R1# show ip eigrp topology 10.1.1.0/24 detail IP-EIGRP (AS 100): Topology entry for 10.1.1.0/24 State: Passive, Query origin flag: 1, 1 Successor(s), FD is 131072 Routing Descriptor Blocks: 10.1.2.2 (GigabitEthernet0/0), from 10.1.2.2, Send flag: 0x0 Composite metric: (131072/130816), Route is Internal Vector metric: Minimum bandwidth is 10000 Kbit Total delay is 100 microseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 1 Originating router: 10.1.2.2 External data: Not advertised Protocol: EIGRP Route tag: 0 Extended community: None What does this output indicate?

medium
  • A.The route is an external EIGRP route redistributed from another protocol.
  • B.The route is learned from a single neighbor and is in a stable state.
  • C.The route has multiple successors and is load-balanced.
  • D.The route is in Active state, meaning a query is in progress.

Why B: The output shows detailed information about the EIGRP topology entry for 10.1.1.0/24. The route is internal, with a single successor via 10.1.2.2. The FD is 131072, and the RD is 130816. The route is in Passive state.

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Last reviewed: Jul 4, 2026

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