The correct answer is that voice traffic receives strict priority up to 10% of the interface bandwidth, video is guaranteed at least 30%, and all remaining traffic is fair-queued. This is because the `priority percent 10` command under class VOICE implements strict priority queuing, ensuring voice packets are transmitted before any other class, but it also polices that priority traffic to a maximum of 10% to prevent starvation. The `bandwidth percent 30` command under class VIDEO provides a minimum bandwidth guarantee using CBWFQ, meaning video will always get at least 30% of the link when there is congestion, while the `fair-queue` on class-default allows all other traffic to share the leftover bandwidth equitably. On the ENCOR 350-401 exam, this combination tests your understanding that priority and bandwidth can coexist in a single policy-map, but a common trap is assuming priority traffic can exceed its allocated percentage—it cannot, as the policer drops excess priority traffic. A helpful memory tip is “Priority first, then bandwidth, then fair-queue—the QoS hierarchy of service.”
CCNP Enterprise Network Design Practice Question
This 350-401 practice question tests your understanding of enterprise network design. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Voice traffic gets strict priority up to 10% of interface bandwidth, video gets at least 30%, and all other traffic is fair-queued.
Option A is correct because the policy-map uses the 'priority percent 10' command under class VOICE, which provides strict priority queuing for voice traffic, guaranteeing it is serviced first up to 10% of the interface bandwidth. The 'bandwidth percent 30' command under class VIDEO allocates a minimum bandwidth guarantee of 30% for video traffic, while the 'fair-queue' command under class-default ensures all other traffic shares the remaining bandwidth fairly using Cisco's Class-Based Weighted Fair Queuing (CBWFQ). This configuration is valid and commonly used in enterprise QoS designs to prioritize real-time traffic while still providing bandwidth guarantees for other critical 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.
✓
Voice traffic gets strict priority up to 10% of interface bandwidth, video gets at least 30%, and all other traffic is fair-queued.
Why this is correct
This is the correct interpretation of the policy-map.
Related concept
Read the scenario before looking for a memorised answer.
✗
Voice and video both get priority queuing, with voice at 10% and video at 30%.
Why it's wrong here
Only the 'priority' command provides strict priority; 'bandwidth' does not.
✗
The policy-map is invalid because you cannot use both priority and bandwidth in the same policy-map.
Why it's wrong here
It is valid to mix priority and bandwidth classes in a policy-map.
✗
The policy-map will only shape traffic, not prioritize it.
Why it's wrong here
There is no shaping command; this is a queuing policy.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that 'priority' and 'bandwidth' cannot coexist in the same policy-map, or that 'bandwidth' implies priority queuing, when in fact they serve different roles (strict priority vs. guaranteed minimum bandwidth) and are commonly used together in enterprise QoS designs.
Trap categories for this question
Command / output trap
Only the 'priority' command provides strict priority; 'bandwidth' does not.
Detailed technical explanation
How to think about this question
Under the hood, the 'priority percent' command creates a strict priority queue (LLQ - Low Latency Queuing) that is serviced before any other queues, but it is policed to the specified percentage to prevent starvation of other traffic. The 'bandwidth percent' command under CBWFQ guarantees a minimum bandwidth during congestion, but the actual bandwidth can exceed this if other classes are not using their allocation. A subtle behavior is that if the priority queue exceeds its allocated 10%, excess voice packets are dropped (not queued), which protects voice quality by avoiding delay variation (jitter) from queue buildup.
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.
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.
Enterprise Network Design — This question tests Enterprise Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Voice traffic gets strict priority up to 10% of interface bandwidth, video gets at least 30%, and all other traffic is fair-queued. — Option A is correct because the policy-map uses the 'priority percent 10' command under class VOICE, which provides strict priority queuing for voice traffic, guaranteeing it is serviced first up to 10% of the interface bandwidth. The 'bandwidth percent 30' command under class VIDEO allocates a minimum bandwidth guarantee of 30% for video traffic, while the 'fair-queue' command under class-default ensures all other traffic shares the remaining bandwidth fairly using Cisco's Class-Based Weighted Fair Queuing (CBWFQ). This configuration is valid and commonly used in enterprise QoS designs to prioritize real-time traffic while still providing bandwidth guarantees for other critical traffic.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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