hardMultiple ChoiceObjective-mapped
300-410 Practice Question: Router R1 is running EIGRP in VRF-A with two…
Router R1 is running EIGRP in VRF-A with two neighbors: R2 and R3. R2 is a directly connected router, R3 is reachable via R2. The network is experiencing EIGRP stuck-in-active (SIA) routes for prefixes learned from R3. R1 configuration: router eigrp 100, address-family ipv4 vrf VRF-A, network 10.0.0.0. R2 is configured similarly. The link between R1 and R2 is a serial link with low bandwidth. 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
✓
The low-bandwidth serial link between R1 and R2 causes EIGRP query packets to be delayed, exceeding the active timer and resulting in SIA.
EIGRP SIA occurs when a query is sent to a neighbor and the reply is not received within the active timer (default 3 minutes). In a VRF-Lite scenario, if the query scope is not limited, the query may propagate to R3 via R2, but if the serial link has low bandwidth or high delay, the query may time out. However, the most common cause in VRF-Lite is that the query is sent to all neighbors, and if one neighbor (R2) does not reply due to a slow link, SIA occurs. The issue is that the query scope includes R2, but the link is slow, causing the active timer to expire.
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 low-bandwidth serial link between R1 and R2 causes EIGRP query packets to be delayed, exceeding the active timer and resulting in SIA.
Why this is correct
Correct: Slow link can delay query/reply packets, leading to SIA.
- ✗
The VRF configuration on R2 is missing the network statement for the link to R3.
Why it's wrong here
Incorrect: This would cause missing routes, not SIA.
- ✗
EIGRP is not supported in VRF-Lite.
Why it's wrong here
Incorrect: EIGRP is supported in VRF-Lite.
- ✗
The active timer should be increased to prevent SIA.
Why it's wrong here
Incorrect: While increasing the timer may mask the issue, the root cause is the slow link; the question asks for root cause.
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
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
Key term
MPLS Layer 3 VPN
A technology that uses Multiprotocol Label Switching to create secure, scalable virtual private networks that connect multiple sites at the network layer, where the service provider manages routing between customer sites.
About these practice questions
One of 1,966 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.