Question 1,521 of 2,152
EIGRP TroubleshootingmediumMultiple ChoiceObjective-mapped

EIGRP Variance: Enabling Unequal-Cost Load Balancing

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. A key principle to apply: variance. 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.

Consider the following EIGRP configuration on Router R4:

router eigrp 300

variance 2

network 172.16.0.0

What is the purpose of the variance command?

Quick Answer

The answer is that the variance command enables unequal-cost load balancing with a factor of 2. This is correct because EIGRP, by default, only installs the single best path (the successor) into the routing table, but the variance command instructs the router to consider any feasible successor whose metric is less than or equal to the variance multiplier times the best metric. With a variance of 2, any path with a metric up to twice the best metric becomes eligible for load balancing, allowing traffic to be distributed across unequal-cost links. On the Cisco CCNP ENARSI 300-410 exam, this command tests your understanding of EIGRP path selection and load balancing, often appearing in configuration scenarios where you must distinguish between equal-cost (default) and unequal-cost behavior. A common trap is forgetting that the path must also be a feasible successor—variance alone does not bypass the feasibility condition. Memory tip: think of variance as a “multiplier” that widens the metric window, so a variance of 2 doubles the acceptable metric range for load balancing.

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

It allows load balancing over paths with metrics up to twice the best metric.

The variance command in EIGRP allows unequal-cost load balancing by instructing the router to include routes in the routing table whose metric is less than or equal to the best metric multiplied by the variance value. With variance 2, any feasible successor route with a metric up to twice the best metric (i.e., ≤ best_metric × 2) will be installed and used for load balancing, provided it satisfies the feasibility condition (reported distance < feasible distance). Only option B accurately describes this behavior; option C is tempting but less precise because unequal-cost load balancing also requires feasible successors.

Key principle: Variance

Answer analysis

Option-by-option breakdown

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

  • It sets the maximum number of equal-cost paths to 2.

    Why it's wrong here

    Incorrect. The variance command does not set the maximum number of equal-cost paths; that is the function of the 'maximum-paths' command.

  • It allows load balancing over paths with metrics up to twice the best metric.

    Why this is correct

    Correct. Variance 2 allows any feasible successor with a metric ≤ 2 × best metric to be installed and used for load balancing.

    Related concept

    Variance

  • It enables unequal-cost load balancing with a factor of 2.

    Why it's wrong here

    Incorrect. While variance does enable unequal-cost load balancing, this option is imprecise because it implies variance alone suffices; the feasibility condition must also be satisfied.

  • It sets the EIGRP metric weight for delay to 2.

    Why it's wrong here

    Incorrect. The variance command does not set metric weights; metric weights are configured with the 'metric weights' command.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between 'variance' (which enables unequal-cost load balancing) and 'maximum-paths' (which limits the number of paths), leading candidates to mistakenly think variance controls the number of paths.

Trap categories for this question

  • Command / output trap

    Incorrect. The variance command does not set the maximum number of equal-cost paths; that is the function of the 'maximum-paths' command.

Detailed technical explanation

How to think about this question

Under the hood, EIGRP uses the Diffusing Update Algorithm (DUAL) to maintain loop-free paths. The variance multiplier only applies to routes that are already feasible successors (i.e., the next-hop router's reported distance is less than the local router's feasible distance). A common real-world scenario is using variance to load balance over a slower backup link (e.g., T1 vs. 100 Mbps) without waiting for equal metrics, but the feasibility condition ensures no routing loops occur.

KKey Concepts to Remember

  • Variance
  • Feasibility Condition

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

Variance

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. Variance 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.

What to study next

Got this wrong? Here's your next step.

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

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FAQ

Questions learners often ask

What does this 300-410 question test?

EIGRP Troubleshooting — This question tests EIGRP Troubleshooting — Variance.

What is the correct answer to this question?

The correct answer is: It allows load balancing over paths with metrics up to twice the best metric. — The variance command in EIGRP allows unequal-cost load balancing by instructing the router to include routes in the routing table whose metric is less than or equal to the best metric multiplied by the variance value. With variance 2, any feasible successor route with a metric up to twice the best metric (i.e., ≤ best_metric × 2) will be installed and used for load balancing, provided it satisfies the feasibility condition (reported distance < feasible distance). Only option B accurately describes this behavior; option C is tempting but less precise because unequal-cost load balancing also requires feasible successors.

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

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

What is the key concept behind this question?

Variance

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Last reviewed: Jul 4, 2026

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