350-501 Automation and Quality of Service Practice Question
Which THREE are common causes of QoS misconfiguration on PE routers? (Choose three.)
⚠ Common exam trap
Cisco often tests the distinction between QoS misconfiguration (e.g., wrong direction, incorrect match criteria) and capacity issues (e.g., insufficient bandwidth), so candidates mistakenly select 'insufficient bandwidth' as a misconfiguration when it is actually a resource constraint that QoS cannot fix.
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
✓
Applying a policy-map in the wrong direction (input vs output).
Applying a policy-map in the wrong direction (input vs output) is a common QoS misconfiguration because QoS actions like shaping, policing, and queuing are direction-specific. For example, shaping is typically applied on the egress interface to control outbound traffic, while policing can be applied inbound to rate-limit incoming traffic. Misapplying a policy-map (e.g., attaching a shaper to the input direction) will either be ignored by the router or cause unexpected behavior, leading to QoS failures.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Applying a policy-map in the wrong direction (input vs output).
Why this is correct
Correct: Common mistake that causes policy to have no effect.
- ✗
Using the 'bandwidth percent' command in a class that also has a priority queue.
Why it's wrong here
Valid in some implementations; not a misconfiguration per se.
- ✗
Insufficient bandwidth on the subscriber line.
Why it's wrong here
This is a capacity issue, not a misconfiguration.
- ✓
Class-map match criteria that do not correctly identify the intended traffic.
Why this is correct
Correct: Leading to improper QoS treatment.
- ✓
Attaching a QoS policy to a VRF interface using a policy-map that references a non-VRF-aware class-map.
Why this is correct
Correct: Policy may not apply to VRF traffic correctly.
Go deeper
Related to this question
About these practice questions
One of 971 original 350-501 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
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.