350-501 Automation and Quality of Service Practice Question
A service provider uses an MPLS-TE tunnel to carry voice and data traffic. The tunnel is experiencing packet loss during congestion. The engineer wants to ensure that voice traffic receives guaranteed bandwidth and low latency while data traffic uses remaining bandwidth. Which QoS configuration should be applied on the tunnel interface?
⚠ Common exam trap
Cisco often tests the misconception that CBWFQ alone can provide low latency for voice, but the trap here is that CBWFQ lacks a strict priority queue, so voice traffic will experience delay and jitter, making LLQ the only correct choice for real-time traffic.
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
✓
LLQ with a priority queue for voice and a default class for data
Low Latency Queuing (LLQ) allows you to place voice traffic into a strict priority queue, ensuring guaranteed bandwidth and low latency during congestion, while the default class uses CBWFQ to allocate remaining bandwidth to data traffic. This matches the requirement of prioritizing voice without starving data entirely, as the priority queue is policed to prevent voice from consuming all bandwidth.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
LLQ with a priority queue for voice and a default class for data
Why this is correct
LLQ ensures low latency for voice, and the default class uses remaining bandwidth for data.
- ✗
CBWFQ with bandwidth allocation for voice and data
Why it's wrong here
CBWFQ does not provide strict priority for voice, potentially causing latency.
- ✗
Policing on voice traffic to limit its rate
Why it's wrong here
Policing discards excess traffic but does not guarantee bandwidth or low latency.
- ✗
Shaping on the tunnel to 75% of bandwidth with no queuing
Why it's wrong here
Shaping without queuing does not prioritize voice over data.
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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.