350-401 Virtualization Practice Question
A network engineer is configuring a Cisco CSR 1000v router in a virtualized environment. The engineer needs to ensure that the router can forward traffic between multiple virtual routing and forwarding (VRF) instances while maintaining isolation. Which technology should the engineer use to allow communication between specific VRFs?
⚠ Common exam trap
The trap here is thinking that any tunneling or routing policy can enable inter-VRF communication, when VRF leaking is the specific and standard feature designed for this purpose.
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
✓
VRF leaking
VRF leaking is the correct technology because it allows specific routes to be imported from one VRF into another, enabling controlled communication while preserving isolation. This is typically done using route targets and route maps. Other options like GRE tunneling or policy-based routing can be used in specific cases but are not the standard method for inter-VRF communication on a single router.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
VRF leaking
Why this is correct
VRF leaking allows routes to be selectively imported and exported between VRF instances, enabling controlled communication while maintaining isolation for other traffic. This is the standard method to allow specific inter-VRF communication on Cisco IOS-XE routers without merging the routing tables entirely.
- ✗
Policy-based routing
Why it's wrong here
Policy-based routing (PBR) allows forwarding decisions based on policies rather than destination routing tables. It can be used to direct traffic between VRFs, but it is not a scalable or standard solution for enabling inter-VRF communication; it is more suited for specific traffic engineering scenarios.
- ✗
VLAN trunking
Why it's wrong here
VLAN trunking is a Layer 2 mechanism to carry multiple VLANs over a single link. It does not provide Layer 3 communication between VRFs, as VRFs operate at Layer 3 and require route leaking or tunneling to exchange routes.
- ✗
GRE tunneling
Why it's wrong here
GRE tunneling encapsulates packets to create point-to-point tunnels between routers, but it does not directly enable communication between VRFs on the same router. While it can be used to connect VRFs across devices, it is not the primary method for inter-VRF routing on a single router.
Go deeper
Related to this question
Learn chapter
Route Redistribution and Filtering
Key term
GRE
GRE (Generic Routing Encapsulation) is a tunneling protocol that encapsulates packets inside other packets to transport them across incompatible networks.
Key term
Virtual Routing and Forwarding
Virtual Routing and Forwarding (VRF) is a technology that allows a single physical router to operate like multiple independent routers by keeping separate routing tables and forwarding decisions for each instance.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.