mediumMultiple Choice
300-410 Practice Question: An engineer is troubleshooting an EIGRP issue…
An engineer is troubleshooting an EIGRP issue where a router is not learning any routes from a neighbor, but the neighbor adjacency is up. The engineer checks the EIGRP topology table on the local router and sees that the neighbor is listed, but no routes from that neighbor are present. The engineer also verifies that the neighbor has routes to advertise. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the distinction between conditions that prevent adjacency formation (like mismatched K values or AS numbers) versus conditions that allow adjacency but suppress route advertisement (like stub configuration), leading candidates to incorrectly select metric weight mismatches when the adjacency is already up.
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 neighbor is configured as an EIGRP stub router.
When an EIGRP neighbor adjacency is up but no routes are received from the neighbor, the most likely cause is that the neighbor is configured as an EIGRP stub router. A stub router advertises only a default route or its directly connected and summary routes, depending on the stub setting, and does not advertise all learned routes. Since the engineer confirmed the neighbor has routes to advertise, the stub configuration on the neighbor would prevent those routes from being sent, even though the adjacency remains established.
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 neighbor is configured as an EIGRP stub router.
Why this is correct
An EIGRP stub router advertises only its connected, summary or static routes, so the adjacency stays up while the local router receives no routes from it. That matches the topology table showing the neighbour but no learned prefixes.
- ✗
The local router has a distribute-list out applied to the neighbor.
Why it's wrong here
A distribute-list out filters routes the local router advertises to that neighbour, so the neighbour's topology table would be empty, not the local one. It is the correct tool for controlling what you send; here the local router is failing to receive, so the filter must be inbound.
- ✗
The EIGRP metric weights are different on the two routers.
Why it's wrong here
Mismatched K-values prevent the routers forming an adjacency at all, because EIGRP validates metric weights in hello packets. The stem states the adjacency is up, so weights already match. K-values are configured identically when you want a neighbour relationship to establish in the first place.
- ✗
The local router has a route-map applied to the EIGRP process that is filtering all routes.
Why it's wrong here
A route-map filtering all routes would remove them from the topology table, but the stem states the neighbour is listed with no routes, which points to a distribute-list or prefix filtering rather than route-map denial. Route-maps are tempting because they filter EIGRP updates, but they would be correct when specific routes are selectively blocked.
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
About these practice questions
One of 1,401 original 300-410 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.