- A
Change the policer to a shaper and apply it to the voice class
Correct because shaping buffers excess traffic instead of dropping it, reducing jitter and packet loss for voice.
- B
Increase the policer rate to 20 Mbps to accommodate voice bursts
Why wrong: Incorrect because the link is only 10 Mbps; over-subscribing the policer can cause drops for other traffic and does not solve the congestion issue.
- C
Remove the policer and rely on FIFO queuing
Why wrong: Incorrect because FIFO does not prioritize voice, leading to increased delay and jitter during congestion.
- D
Apply the policy in the output direction only
Why wrong: Incorrect because the direction does not address the fundamental issue of dropping voice packets; the policy must provide priority queuing.
Quick Answer
The answer is to replace the policer with a shaper or apply a low-latency queue (LLQ) for the voice class. A policer drops excess traffic immediately when the configured rate is exceeded, which directly causes the choppy voice calls and packet loss reported during congestion. In contrast, a shaper buffers the excess traffic and smooths it out over time, while LLQ provides strict priority queuing that ensures voice packets are always sent first, preventing drops entirely. On the ENCOR 350-401 exam, this scenario tests your understanding that policers are suitable for marking or rate-limiting non-critical traffic, but for delay-sensitive voice (EF), you must guarantee bandwidth without drops—LLQ is the go-to mechanism. A common trap is assuming a policer can be tuned to avoid drops, but it inherently discards bursts. Memory tip: “Police drops, Shaper stops, LLQ tops”—meaning policers drop, shapers buffer, and LLQ gives voice top priority.
CCNP QoS Practice Question
This 350-401 practice question tests your understanding of qos. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
An engineer is deploying QoS on a WAN link between two sites using a Cisco ISR 4451 router. The link is a 10 Mbps MPLS circuit. The engineer wants to ensure that voice traffic (EF) is never dropped, even during congestion. The current policy uses a single class map for voice with a policer that drops excess traffic. During peak hours, users report choppy voice calls. What change should the engineer make?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"never"Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
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
Change the policer to a shaper and apply it to the voice class
The correct answer is to replace the policer with a shaper or use a low-latency queue (LLQ) to provide strict priority queuing. A policer drops excess traffic, which can cause voice packet loss. Using LLQ ensures voice gets priority without dropping.
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.
- ✓
Change the policer to a shaper and apply it to the voice class
Why this is correct
Correct because shaping buffers excess traffic instead of dropping it, reducing jitter and packet loss for voice.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the policer rate to 20 Mbps to accommodate voice bursts
Why it's wrong here
Incorrect because the link is only 10 Mbps; over-subscribing the policer can cause drops for other traffic and does not solve the congestion issue.
- ✗
Remove the policer and rely on FIFO queuing
Why it's wrong here
Incorrect because FIFO does not prioritize voice, leading to increased delay and jitter during congestion.
- ✗
Apply the policy in the output direction only
Why it's wrong here
Incorrect because the direction does not address the fundamental issue of dropping voice packets; the policy must provide priority queuing.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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.
What to study next
Got this wrong? Here's your next step.
Identify which 350-401 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
- →
QoS — study guide chapter
Learn the concepts, then practise the questions
- →
QoS practice questions
Targeted practice on this topic area only
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FAQ
Questions learners often ask
What does this 350-401 question test?
QoS — This question tests QoS — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Change the policer to a shaper and apply it to the voice class — The correct answer is to replace the policer with a shaper or use a low-latency queue (LLQ) to provide strict priority queuing. A policer drops excess traffic, which can cause voice packet loss. Using LLQ ensures voice gets priority without dropping.
What should I do if I get this 350-401 question wrong?
Identify which 350-401 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
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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Last reviewed: Jun 18, 2026
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.
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