350-501 Automation and Quality of Service Practice Question
A service provider is implementing QoS on an MPLS network to support voice, video, and data traffic. Which queuing mechanism provides the lowest latency for real-time traffic?
⚠ Common exam trap
Cisco often tests the misconception that CBWFQ alone can handle real-time traffic, but the trap is that CBWFQ lacks a strict priority queue, so only LLQ provides the necessary low-latency guarantee for voice and video.
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
LLQ (Low Latency Queuing) is the correct choice because it provides a strict priority queue specifically designed for real-time traffic like voice and video. By placing delay-sensitive packets into a dedicated priority queue that is serviced before all other queues, LLQ ensures minimal and predictable latency, which is essential for maintaining voice quality in an MPLS network.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
FIFO
Why it's wrong here
FIFO provides no traffic differentiation, leading to unpredictable latency.
- ✗
WRED
Why it's wrong here
WRED is a congestion avoidance mechanism that drops packets probabilistically, not a queuing mechanism.
- ✓
LLQ
Why this is correct
LLQ provides a strict priority queue that ensures low latency and jitter for real-time traffic.
- ✗
CBWFQ
Why it's wrong here
CBWFQ uses class-based weighted fair queuing but does not provide a strict priority queue for real-time traffic.
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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.