350-501 LLQ (Low Latency Queueing) Practice Question
An SP engineer is configuring hierarchical QoS on a PE router for a subscriber with a 10 Mbps shaped rate. The child policy must guarantee 2 Mbps for voice, 4 Mbps for video, and the rest for data. However, the parent policy shape rate is 10 Mbps. Which configuration ensures proper operation?
⚠ Common exam trap
Voice traffic requires low-latency treatment; using the bandwidth command instead of priority is a common mistake.
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
✓
Parent shape 10 Mbps, child policy with LLQ for voice and CBWFQ for video and data with bandwidth 5 Mbps each
In hierarchical QoS, the child policy must respect the parent shape rate of 10 Mbps while providing low-latency for voice. The correct approach is to use LLQ (priority) for voice to ensure low delay and jitter, and CBWFQ for video and data to allocate bandwidth within the shape. Option A uses LLQ for voice and allocates 5 Mbps each to video and data via CBWFQ, totaling 10 Mbps, which fits within the parent shape. Option D incorrectly uses the bandwidth command for voice, which does not provide the necessary low-latency treatment. Options B and C either miss a data class or use bandwidth percent for voice, not priority.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Parent shape 10 Mbps, child policy with LLQ for voice and CBWFQ for video and data with bandwidth 5 Mbps each
Why this is correct
Correct. Uses LLQ for voice, ensuring low-latency, and CBWFQ for video and data with bandwidth summing to the shape rate.
- ✗
Parent shape 10 Mbps, child policy with priority for voice and bandwidth 4 Mbps for video, no data class
Why it's wrong here
Incorrect. Missing a data class; the default class would not guarantee data bandwidth.
- ✗
Parent shape 10 Mbps, child policy with bandwidth percent 20 voice, 40 video, and 40 data
Why it's wrong here
Incorrect. Uses bandwidth percent for voice, not priority, which does not ensure low-latency.
- ✗
Parent shape 10 Mbps, child policy with bandwidth 2 Mbps for voice, 4 Mbps for video, and default class for data
Why it's wrong here
Incorrect. Voice should be configured with priority (LLQ), not bandwidth, to meet latency requirements.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.