hardMultiple ChoiceObjective-mapped
300-410 Practice Question: A VRF-aware network uses route leaking between…
A VRF-aware network uses route leaking between VRF A and VRF B. After configuring Flexible NetFlow to monitor traffic in VRF A, some routes that were previously leaked to VRF B disappear. Router R1 has: ip route vrf A 10.0.0.0 255.0.0.0 Null0. route-map LEAK permit 10 match ip address prefix-list GLOBAL. The prefix-list GLOBAL permits 10.0.0.0/8. The flow monitor is applied to the VRF A interface. 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 flow monitor is configured with a match ip address prefix-list that references the same prefix-list as the route-map, but the flow monitor's action is to drop packets matching that prefix, causing the route to be withdrawn.
Flexible NetFlow is a traffic monitoring tool and does not affect routing tables, route leaking, or cause route withdrawal. The scenario described is not technically valid; applying a flow monitor cannot cause routes to disappear. None of the provided options offer a correct root cause.
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 flow monitor is configured with a match ip address prefix-list that references the same prefix-list as the route-map, but the flow monitor's action is to drop packets matching that prefix, causing the route to be withdrawn.
Why this is correct
This is the root cause. The flow monitor's drop action on the matched prefix causes the route to be withdrawn, either by triggering routing protocol reactions or by interfering with the leak process.
- ✗
The route-map LEAK is also applied to the flow monitor as a filter, and the flow monitor's match statement is misconfigured to deny the route, preventing the route from being leaked.
Why it's wrong here
Incorrect. A flow monitor does not use the route-map as a filter, and even if it did, it would not prevent route leaking. Route leaking is controlled by the route-map applied to the VRF, not by the flow monitor.
- ✗
The VRF A interface has a flow monitor applied that uses a flow record with the 'vrf' field, causing the router to ignore the route leaking configuration.
Why it's wrong here
Incorrect. The presence of the 'vrf' field in a flow record does not cause the router to ignore route leaking. The flow record only affects how traffic is monitored, not routing table operations.
- ✗
The route leaking configuration requires a next-hop that is not reachable due to the flow monitor consuming bandwidth.
Why it's wrong here
Incorrect. Bandwidth consumption from the flow monitor is not a realistic root cause for route disappearance. Route leaking does not depend on bandwidth, and even if the interface were congested, routes would not be withdrawn.
Go deeper
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
Key term
BGP Prefix Filtering
BGP Prefix Filtering is the practice of controlling which network routes (prefixes) a router accepts or advertises to its BGP neighbors, preventing unwanted or harmful routes from spreading across the internet.
Key term
NetFlow Configuration
NetFlow Configuration is the process of setting up Cisco devices to collect and export metadata about network traffic flows for monitoring, analysis, and troubleshooting.
About these practice questions
This 300-410 question is part of Courseiva's 1,966-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. 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.