The answer is that the centralized data policy lacks a match condition for the correct VPN or site list. This is the most likely reason for the failure because a Cisco SD-WAN centralized data policy on the vSmart must define not only the traffic match (like DSCP EF for voice) but also the scope of enforcement through a site list or VPN list. Without this scope, the vEdge routers, even though they receive and activate the policy, have no instruction to apply the preferred color 'mpls' specifically to the branch-to-branch traffic, so they fall back to default routing, which may choose the lower-latency Internet link. On the ENCOR 350-401 exam, this tests your understanding of how centralized data policies are structured and applied, with a common trap being that engineers focus only on the traffic match and forget the site or VPN context. Remember the mnemonic "Traffic plus Scope equals Policy"—without both, the policy is just a template with no teeth.
350-401 SD-WAN Architecture Practice Question
This 350-401 practice question tests your understanding of sd-wan architecture. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
A large enterprise uses Cisco SD-WAN with multiple transport clouds (MPLS and Internet). The network team wants to ensure that voice traffic between two branch offices always uses the MPLS link, even if the Internet link has lower latency. The engineer creates a centralized data policy on the vSmart to match voice traffic based on DSCP EF and sets the preferred color to 'mpls'. After applying the policy, the engineer tests and finds that voice traffic is still using the Internet link. The vEdge routers show that the policy is received and active. What is the most likely reason for this failure?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Clue: "always"
Why it matters: Absolute qualifier. An answer using 'always' is only correct if there are genuinely no exceptions — absolute statements are often wrong in networking.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The policy does not include a match condition for the correct VPN or site list.
Option D is correct because a centralized data policy on the vSmart must include match conditions for both the traffic (e.g., DSCP EF) and the scope of the policy (e.g., VPN list or site list). Without a site list or VPN list match, the policy may not apply to the specific branch-to-branch traffic, causing the vEdge to fall back to the default routing behavior (e.g., using the Internet link if it has lower latency). The vSmart distributes the policy to vEdges, but the vEdge only enforces it for matched traffic within the specified sites or VPNs.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 vEdge routers have not rebooted after the policy was applied.
Why it's wrong here
Incorrect because policy changes take effect immediately without reboot.
✗
The data policy was applied on the vEdge instead of the vSmart.
Why it's wrong here
Incorrect because the engineer stated the policy was applied on the vSmart.
✗
The DSCP EF marking is not supported in SD-WAN data policies.
The policy does not include a match condition for the correct VPN or site list.
Why this is correct
Correct because the policy must be associated with the specific VPN and site list to apply to the traffic.
Clue confirmation
The clue words "most likely", "always" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a centralized data policy with only traffic match conditions (like DSCP) will automatically apply to all traffic, when in reality the policy must also include a site list or VPN list to define the scope of enforcement.
Detailed technical explanation
How to think about this question
In Cisco SD-WAN, centralized data policies are defined on the vSmart and pushed to vEdge routers via OMP (Overlay Management Protocol). The policy must include a 'site-list' or 'vpn-list' to define which sites or VPNs the policy applies to; without this, the policy may be received and active but not match the traffic between the two branch offices. Additionally, the 'preferred color' action in a centralized data policy only influences path selection if the traffic matches the policy's match conditions, and if no match occurs, the vEdge uses the default OMP best-path selection, which may prefer lower latency links.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 350-401 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
SD-WAN Architecture — This question tests SD-WAN Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The policy does not include a match condition for the correct VPN or site list. — Option D is correct because a centralized data policy on the vSmart must include match conditions for both the traffic (e.g., DSCP EF) and the scope of the policy (e.g., VPN list or site list). Without a site list or VPN list match, the policy may not apply to the specific branch-to-branch traffic, causing the vEdge to fall back to the default routing behavior (e.g., using the Internet link if it has lower latency). The vSmart distributes the policy to vEdges, but the vEdge only enforces it for matched traffic within the specified sites or VPNs.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely", "always". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network engineer is configuring a Cisco SD-WAN solution for a multinational corporation. The engineer wants to use a centralized data policy to steer all traffic from the Finance department (VPN 10) to a specific WAN link (MPLS) for security reasons. The engineer creates a policy that matches traffic from VPN 10 and sets the preferred color to 'mpls'. After applying the policy, the engineer tests and finds that traffic from VPN 10 is still using the Internet link. The vEdge routers show that the policy is received and active. What is the most likely reason?
easy
A.The vEdge routers have not rebooted after the policy was applied.
✓ B.The policy is not attached to the correct site list or VPN list.
C.The data policy was applied on the vEdge instead of the vSmart.
D.The preferred color is not configured correctly in the policy.
Why B: The most likely reason is that the centralized data policy was not attached to the correct site list or VPN list. In Cisco SD-WAN, a centralized data policy must be explicitly associated with the sites (via site list) and VPNs (via VPN list) where it should be applied. Even if the policy is received and active on the vEdge routers, without proper attachment to the VPN 10 site list, the policy will not enforce the preferred color 'mpls' for Finance traffic, leaving it to use the default Internet link.
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Question Discussion
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