- A
Mark voice traffic with EXP 5, video with EXP 4, and data with EXP 0, and rely on the core to prioritize based on EXP.
Why wrong: Marking alone does not provide queuing; the PE-CE interfaces need explicit policies.
- B
Use a single-level policy with LLQ for voice and video together, and CBWFQ for data.
Why wrong: LLQ for both voice and video could cause voice to compete with video, violating the requirement that video not affect voice.
- C
Apply a parent policy with a shape for the total bandwidth and a child policy with LLQ for voice and CBWFQ for video and data.
This provides hierarchical control, ensuring voice gets priority within the shaped bandwidth while video and data get fair treatment.
- D
Apply class-based shaping to each traffic class separately on the interface.
Why wrong: Class-based shaping does not provide priority queuing; voice could still be delayed if its queue is full.
Quick Answer
The correct configuration approach is to apply a parent policy with a shape for the total bandwidth and a child policy with LLQ for voice and CBWFQ for video and data. This hierarchical QoS design ensures that voice traffic receives strict priority through Low Latency Queuing, while video is guaranteed bandwidth via Class-Based Weighted Fair Queuing without ever preempting voice, because the parent shaper enforces a hard cap on aggregate throughput. On the Cisco SPCOR 350-501 exam, this scenario tests your understanding of how HQoS decouples shaping at the parent level from queuing at the child level, a common trap being the mistaken belief that a single-level policy with LLQ alone can prevent video from starving voice under congestion. Remember the memory tip: “Parent shapes the pipe, child queues the type”—the parent controls the total rate, while the child policy applies DiffServ treatment using MPLS EXP markings to prioritize voice, video, and data appropriately.
350-501 Automation and Quality of Service Practice Question
This 350-501 practice question tests your understanding of automation and quality of service. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 service provider is designing a QoS policy for a multi-service MPLS VPN network that carries voice, video, and data traffic. The network uses DiffServ and MPLS EXP markings. The design must ensure that voice traffic is given priority over video and data, while video traffic should have better treatment than data but not at the expense of voice. The provider plans to use a hierarchical QoS (HQoS) policy at the PE-CE interfaces. Which configuration approach best meets these requirements?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"best"Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
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
Apply a parent policy with a shape for the total bandwidth and a child policy with LLQ for voice and CBWFQ for video and data.
Option C is correct because hierarchical QoS (HQoS) allows the service provider to enforce a total bandwidth shape at the parent level while using a child policy to apply LLQ for voice (ensuring strict priority) and CBWFQ for video and data (ensuring video gets better treatment than data without starving voice). This meets the requirement that video should not degrade voice, as the parent shape prevents any single class from monopolizing the link, and the child policy’s LLQ guarantees voice priority over all other traffic.
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.
- ✗
Mark voice traffic with EXP 5, video with EXP 4, and data with EXP 0, and rely on the core to prioritize based on EXP.
Why it's wrong here
Marking alone does not provide queuing; the PE-CE interfaces need explicit policies.
- ✗
Use a single-level policy with LLQ for voice and video together, and CBWFQ for data.
Why it's wrong here
LLQ for both voice and video could cause voice to compete with video, violating the requirement that video not affect voice.
- ✓
Apply a parent policy with a shape for the total bandwidth and a child policy with LLQ for voice and CBWFQ for video and data.
Why this is correct
This provides hierarchical control, ensuring voice gets priority within the shaped bandwidth while video and data get fair treatment.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Apply class-based shaping to each traffic class separately on the interface.
Why it's wrong here
Class-based shaping does not provide priority queuing; voice could still be delayed if its queue is full.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a single-level LLQ can handle multiple priority classes together, but the trap here is that combining voice and video in one LLQ queue violates the strict priority requirement for voice over video, which HQoS with separate child policies resolves.
Detailed technical explanation
How to think about this question
HQoS uses a two-level policy-map: the parent policy applies a shape (e.g., 'shape average 10 Mbps') to cap the aggregate rate, while the child policy defines per-class queuing (LLQ for voice, CBWFQ for video and data). The child policy’s LLQ ensures voice packets are dequeued first, and the parent shape prevents the priority queue from starving other queues by limiting the total output rate. In real-world MPLS VPN deployments, this approach aligns with RFC 4594 guidelines for DiffServ traffic classes, where voice (EF) is mapped to EXP 5 and video (AF4) to EXP 4, ensuring consistent behavior across the provider core.
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 350-501 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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Automation and Quality of Service — study guide chapter
Learn the concepts, then practise the questions
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FAQ
Questions learners often ask
What does this 350-501 question test?
Automation and Quality of Service — This question tests Automation and Quality of Service — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Apply a parent policy with a shape for the total bandwidth and a child policy with LLQ for voice and CBWFQ for video and data. — Option C is correct because hierarchical QoS (HQoS) allows the service provider to enforce a total bandwidth shape at the parent level while using a child policy to apply LLQ for voice (ensuring strict priority) and CBWFQ for video and data (ensuring video gets better treatment than data without starving voice). This meets the requirement that video should not degrade voice, as the parent shape prevents any single class from monopolizing the link, and the child policy’s LLQ guarantees voice priority over all other traffic.
What should I do if I get this 350-501 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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This 350-501 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 350-501 exam.
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