- A
VRFs allow multiple customers to share the same physical infrastructure while keeping their traffic isolated.
Correct because each VRF maintains separate forwarding tables, providing Layer 3 isolation.
- B
In MPLS VPN, VRFs are combined with route targets to control route distribution between PE routers.
Correct because route targets (import/export) determine which VRFs receive which routes.
- C
VRF-aware features such as NAT, QoS, and ACLs can be applied per VRF to enforce path isolation policies.
Correct because Cisco IOS supports VRF-aware services for granular control.
- D
VRF can be used to replace VLANs for Layer 2 isolation.
Why wrong: Incorrect because VRF is a Layer 3 concept, while VLANs operate at Layer 2.
- E
In VRF-lite, path isolation is achieved using MPLS labels.
Why wrong: Incorrect because VRF-lite does not use MPLS; it relies on separate routing tables.
350-401 VRF and Path Isolation Practice Question
This 350-401 practice question tests your understanding of vrf and path isolation. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Which three statements about VRF path isolation in a service provider network are true? (Choose three.)
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
VRFs allow multiple customers to share the same physical infrastructure while keeping their traffic isolated.
Correct: VRFs isolate customer traffic; MPLS VPN uses VRFs with route targets; VRF-aware features like NAT and QoS can be applied per VRF. Incorrect: VRFs do not replace VLANs; VRF-lite does not use labels.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
VRFs allow multiple customers to share the same physical infrastructure while keeping their traffic isolated.
Why this is correct
Correct because each VRF maintains separate forwarding tables, providing Layer 3 isolation.
Related concept
Access ports place end devices into a single VLAN.
- ✓
In MPLS VPN, VRFs are combined with route targets to control route distribution between PE routers.
Why this is correct
Correct because route targets (import/export) determine which VRFs receive which routes.
Related concept
Access ports place end devices into a single VLAN.
- ✓
VRF-aware features such as NAT, QoS, and ACLs can be applied per VRF to enforce path isolation policies.
Why this is correct
Correct because Cisco IOS supports VRF-aware services for granular control.
Related concept
Access ports place end devices into a single VLAN.
- ✗
VRF can be used to replace VLANs for Layer 2 isolation.
Why it's wrong here
Incorrect because VRF is a Layer 3 concept, while VLANs operate at Layer 2.
- ✗
In VRF-lite, path isolation is achieved using MPLS labels.
Why it's wrong here
Incorrect because VRF-lite does not use MPLS; it relies on separate routing tables.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
- Access ports place end devices into a single VLAN.
- Trunk ports carry multiple VLANs between switches.
- Allowed VLAN lists decide which VLANs can cross a trunk.
- Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
- Use show vlan brief to verify access VLANs.
- Use show interfaces trunk to verify trunk state and allowed VLANs.
- Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.
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FAQ
Questions learners often ask
What does this 350-401 question test?
VRF and Path Isolation — This question tests VRF and Path Isolation — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: VRFs allow multiple customers to share the same physical infrastructure while keeping their traffic isolated. — Correct: VRFs isolate customer traffic; MPLS VPN uses VRFs with route targets; VRF-aware features like NAT and QoS can be applied per VRF. Incorrect: VRFs do not replace VLANs; VRF-lite does not use labels.
What should I do if I get this 350-401 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 350-401 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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Last reviewed: Jun 18, 2026
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