Question 402 of 2,015

EIGRP →mediumMultiple ChoiceObjective-mapped

350-401 EIGRP Practice Question

This 350-401 practice question tests your understanding of eigrp. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 is troubleshooting an EIGRP issue in a large enterprise network. Two routers, R1 and R2, are connected via a T1 link. R1 is learning a route to 10.0.0.0/8 from R2 with a metric of 28160, but the same route is also learned from another neighbor with a metric of 26880. The engineer notices that the route from R2 is not being installed in the routing table. What is the most likely cause?

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 1mediummultiple choice

Study the full EIGRP explanation →

A
The route from R2 is a feasible successor, so it is not installed in the routing table.
Why wrong: Incorrect. Feasible successors are backup routes stored in the topology table, but the question describes a route that is not installed because a better metric route exists, not because it's a feasible successor.
B
EIGRP is using unequal-cost load balancing, so the higher metric route is not used.
Why wrong: Incorrect. Unequal-cost load balancing (variance) allows multiple routes with different metrics to be used, but by default only the best metric route is installed. The scenario does not mention variance configuration.
C
The route with metric 28160 is not installed because EIGRP selects the route with the lowest metric.
Correct. EIGRP installs only the route with the best (lowest) metric in the routing table. Since 26880 is lower than 28160, the route from R2 is not installed.
D
The route from R2 is a summary route, so it is not installed in the routing table.
Why wrong: Incorrect. Summary routes can be installed in the routing table if they are the best route. The metric difference indicates a non-summary issue.

Full breakdown with real-world context →

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 with metric 28160 is not installed because EIGRP selects the route with the lowest metric.

C is correct because EIGRP installs only the route with the best (lowest) metric into the routing table. The route from R2 has a metric of 28160, while the other neighbor advertises the same route with a metric of 26880. Since 26880 is lower, R1 selects that route as the successor and does not install the higher-metric route from R2.

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 route from R2 is a feasible successor, so it is not installed in the routing table.
Why it's wrong here
Incorrect. Feasible successors are backup routes stored in the topology table, but the question describes a route that is not installed because a better metric route exists, not because it's a feasible successor.
✗
EIGRP is using unequal-cost load balancing, so the higher metric route is not used.
Why it's wrong here
Incorrect. Unequal-cost load balancing (variance) allows multiple routes with different metrics to be used, but by default only the best metric route is installed. The scenario does not mention variance configuration.
✓
The route with metric 28160 is not installed because EIGRP selects the route with the lowest metric.
Why this is correct
Correct. EIGRP installs only the route with the best (lowest) metric in the routing table. Since 26880 is lower than 28160, the route from R2 is not installed.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The route from R2 is a summary route, so it is not installed in the routing table.
Why it's wrong here
Incorrect. Summary routes can be installed in the routing table if they are the best route. The metric difference indicates a non-summary issue.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the misconception that all learned EIGRP routes are installed in the routing table, but in reality only the successor (lowest metric) is installed unless unequal-cost load balancing is explicitly configured.

Trap categories for this question

Scenario analysis trap
Incorrect. Unequal-cost load balancing (variance) allows multiple routes with different metrics to be used, but by default only the best metric route is installed. The scenario does not mention variance configuration.

Detailed technical explanation

How to think about this question

EIGRP uses the Diffusing Update Algorithm (DUAL) to select the successor (best path) based on the lowest feasible distance. The feasible successor must satisfy the feasibility condition: its reported distance must be less than the successor's feasible distance. In this scenario, the route with metric 26880 is the successor, and the route from R2 (28160) may or may not be a feasible successor depending on whether its reported distance is less than the successor's feasible distance. If it is not, it is simply a non-feasible route and is not installed. The 'show ip eigrp topology' command can be used to verify the successor and feasible successor status.

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 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.

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

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FAQ

Questions learners often ask

What does this 350-401 question test?

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

What is the correct answer to this question?

The correct answer is: The route with metric 28160 is not installed because EIGRP selects the route with the lowest metric. — C is correct because EIGRP installs only the route with the best (lowest) metric into the routing table. The route from R2 has a metric of 28160, while the other neighbor advertises the same route with a metric of 26880. Since 26880 is lower, R1 selects that route as the successor and does not install the higher-metric route from R2.

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

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

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?

Read the scenario before looking for a memorised answer.

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