hardMultiple Choice
350-401 Practice Question: An engineer is deploying a new SD-WAN solution…
An engineer is deploying a new SD-WAN solution using Cisco vManage. The WAN edge routers are connected to two different transport networks: MPLS and Internet. The engineer wants to ensure that voice traffic is always sent over the MPLS link when available, and only fails over to the Internet link if the MPLS link goes down. The engineer has configured a policy to set the preferred color for voice traffic to 'mpls'. However, during a test, voice traffic is still using the Internet link even though the MPLS link is up. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the misconception that configuring a policy alone is sufficient, when in fact the policy must be attached to the correct VPN and site list to be activated—candidates overlook the attachment step and assume the policy is automatically applied to all traffic.
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 policy is not attached to the correct VPN or site list.
The most likely cause is that the policy is not attached to the correct VPN or site list. In Cisco SD-WAN, a centralized data policy must be applied to a specific VPN (e.g., VPN 0 for transport, VPN 10 for service-side) and/or a site list to take effect. Even if the policy correctly sets the preferred color to 'mpls', it will not influence traffic forwarding unless it is properly associated with the VPN carrying the voice traffic and the site list containing the affected routers.
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 policy is not attached to the correct VPN or site list.
Why this is correct
In vManage, a preferred-color policy is enforced only after it is attached to a specific VPN or site list via the policy's 'Site and VPN' configuration. If the policy is not bound to the VPN that carries voice traffic, the vSmart controller will not inject the corresponding route attributes, leaving the traffic on its default path. Correct attachment is a prerequisite for any centralized policy to take effect, so a policy that is missing from the correct VPN or site list will silently do nothing.
- ✗
The voice traffic is using a different DSCP value than the one defined in the policy.
Why it's wrong here
Incorrect. The scenario states that the policy sets the preferred color for voice traffic. If the traffic does not match the policy match criteria, it would not be affected, but the question implies the policy is correctly matching voice traffic.
- ✗
The MPLS link is not in the 'up' state in the vManage overlay.
Why it's wrong here
The MPLS link's operational state in the vManage overlay is not a prerequisite for policy application; preferred-color policies are configured independently of transport link status. Even if the MPLS link were down, the policy would still attach to the VPN and attempt to steer traffic to the preferred color, though the path would be unavailable. Since the scenario explicitly states the MPLS link is up, its state cannot be the root cause of the policy not being applied.
- ✗
The policy is configured as a local policy instead of a centralized policy.
Why it's wrong here
While local policies and centralized policies are configured differently, both are capable of setting a preferred color; local policies operate on the device itself, while centralized policies are distributed by vSmart. The fact that a policy is local rather than centralized does not inherently prevent it from matching traffic and applying a preferred color, provided it is attached to the correct interface or VPN. Therefore, the real issue lies not in the policy type but in the attachment to the specific VPN or site list, which affects both policy types equally.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.