- A
Implement hierarchical QoS (HQoS) with a parent policy shaping per-tenant traffic and a child policy applying class-based weighted fair queuing (CBWFQ) for each tenant's applications.
HQoS provides per-tenant shaping and per-class queuing, meeting the requirements for fairness and isolation.
- B
Use a single level of CBWFQ on all interfaces, classifying traffic by tenant using VLANs.
Why wrong: Single-level CBWFQ cannot enforce per-tenant bandwidth limits; tenants could starve each other.
- C
Apply strict priority queuing for all mission-critical traffic across all tenants.
Why wrong: This would allow one tenant's critical traffic to monopolize bandwidth, violating fairness.
- D
Configure separate physical interfaces for each tenant and apply independent QoS policies.
Why wrong: This is not scalable and wastes ports; HQoS is designed for multi-tenant environments on shared interfaces.
Quick Answer
The correct choice is hierarchical QoS (HQoS) with a parent policy shaping per-tenant traffic and a child policy applying class-based weighted fair queuing (CBWFQ) for each tenant’s applications. This two-level structure enforces per-tenant fairness by using the parent shaper to cap each tenant’s aggregate bandwidth, preventing any single tenant from monopolizing the leaf-spine uplink, while the child CBWFQ policy prioritizes each tenant’s mission-critical flows over their own best-effort traffic. On the ENCOR 350-401 exam, this scenario tests your understanding of how HQoS solves multi-tenant isolation in modern data center designs—a common trap is confusing simple CBWFQ (which only prioritizes within a single queue) with the hierarchical approach needed for inter-tenant guarantees. Remember the memory tip: “Parent shapes the tenant, child sorts the apps”—the parent enforces the fairness boundary between tenants, and the child handles internal application priority.
CCNP QoS Architecture Practice Question
This 350-401 practice question tests your understanding of qos architecture. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 network team is designing QoS for a multi-tenant data center using leaf-spine architecture. Each tenant requires guaranteed bandwidth for their mission-critical applications, while best-effort traffic must not interfere. The design must use hierarchical queuing to enforce per-tenant fairness. Which queuing mechanism should the architect implement on the leaf switches?
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
Implement hierarchical QoS (HQoS) with a parent policy shaping per-tenant traffic and a child policy applying class-based weighted fair queuing (CBWFQ) for each tenant's applications.
Hierarchical QoS (HQoS) is the correct choice because it allows the architect to enforce per-tenant bandwidth guarantees using a parent policy (shaping) while applying class-based weighted fair queuing (CBWFQ) in a child policy to prioritize each tenant's mission-critical applications. This two-level structure ensures that best-effort traffic from one tenant cannot starve another tenant's guaranteed traffic, meeting the multi-tenant fairness requirement.
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.
- ✓
Implement hierarchical QoS (HQoS) with a parent policy shaping per-tenant traffic and a child policy applying class-based weighted fair queuing (CBWFQ) for each tenant's applications.
Why this is correct
HQoS provides per-tenant shaping and per-class queuing, meeting the requirements for fairness and isolation.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use a single level of CBWFQ on all interfaces, classifying traffic by tenant using VLANs.
Why it's wrong here
Single-level CBWFQ cannot enforce per-tenant bandwidth limits; tenants could starve each other.
- ✗
Apply strict priority queuing for all mission-critical traffic across all tenants.
Why it's wrong here
This would allow one tenant's critical traffic to monopolize bandwidth, violating fairness.
- ✗
Configure separate physical interfaces for each tenant and apply independent QoS policies.
Why it's wrong here
This is not scalable and wastes ports; HQoS is designed for multi-tenant environments on shared interfaces.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a single level of CBWFQ or strict priority queuing can achieve per-tenant fairness, but without hierarchical shaping, one tenant's bursty traffic can consume all available bandwidth, breaking the isolation required in multi-tenant environments.
Detailed technical explanation
How to think about this question
HQoS uses a parent policy to shape traffic to a per-tenant committed information rate (CIR) and a child policy to apply CBWFQ for application-level queues (e.g., voice, video, data). Under the hood, the parent policy's shaper meters traffic and drops or marks packets exceeding the CIR, while the child policy's CBWFQ uses weighted round-robin scheduling to allocate bandwidth among classes, ensuring that within a tenant, mission-critical traffic gets priority over best-effort. In a real-world leaf-spine data center, this is often implemented using MQC (Modular QoS CLI) with nested policy maps on the leaf switch's egress interfaces toward the spine.
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 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
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FAQ
Questions learners often ask
What does this 350-401 question test?
QoS Architecture — This question tests QoS Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Implement hierarchical QoS (HQoS) with a parent policy shaping per-tenant traffic and a child policy applying class-based weighted fair queuing (CBWFQ) for each tenant's applications. — Hierarchical QoS (HQoS) is the correct choice because it allows the architect to enforce per-tenant bandwidth guarantees using a parent policy (shaping) while applying class-based weighted fair queuing (CBWFQ) in a child policy to prioritize each tenant's mission-critical applications. This two-level structure ensures that best-effort traffic from one tenant cannot starve another tenant's guaranteed traffic, meeting the multi-tenant fairness requirement.
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: "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.
About these practice questions
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Last reviewed: Jun 24, 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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