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350-401 Practice Question: Which three statements about Cisco QoS queuing…
Which three statements about Cisco QoS queuing and scheduling are true? (Choose three.)
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
✓
Strict priority queuing ensures that voice traffic is always sent before other traffic.
Queuing manages packets when output is congested, and scheduling determines the order of transmission. Cisco uses multiple queues (e.g., 4 queues on Catalyst switches) with strict priority or weighted round-robin (WRR). Option A is correct because strict priority queue (PQ) ensures low-latency for voice. Option B is correct because WRR (or shaped round robin) is used for non-priority queues. Option C is correct because the default queue is usually queue 1 (or the best-effort queue). Option D is incorrect because tail drop is a congestion avoidance mechanism applied to a queue, not a scheduling method. Option E is incorrect because scheduling occurs on the egress interface, not ingress.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Strict priority queuing ensures that voice traffic is always sent before other traffic.
Why this is correct
Correct because strict priority queue guarantees low latency for delay-sensitive traffic like voice.
- ✓
Weighted Round Robin (WRR) is used to service non-priority queues in a round-robin fashion based on configured weights.
Why this is correct
Correct because WRR allocates bandwidth proportionally among non-priority queues.
- ✓
On Cisco Catalyst switches, the default queue (queue 1) is typically used for best-effort traffic.
Why this is correct
Correct because queue 1 is the default best-effort queue on many Catalyst platforms.
- ✗
Tail drop is a scheduling algorithm that determines which queue to service next.
Why it's wrong here
Incorrect because tail drop is a congestion avoidance mechanism that drops packets when a queue is full, not a scheduling algorithm.
- ✗
Queuing and scheduling are performed on the ingress interface before routing decisions.
Why it's wrong here
Incorrect because queuing and scheduling are egress functions, performed after the packet is switched to the output interface.
Go deeper
Related to this question
Learn chapter
SDN Controllers and Cisco ACI
Key term
QoS Queuing and Shaping
QoS Queuing and Shaping is a set of traffic management techniques that control how network packets are prioritized, delayed, or smoothed to ensure critical applications perform well even during congestion.
Key term
QoS Classification and Marking
QoS Classification and Marking is the process of identifying network traffic by type and assigning a priority label to ensure important data gets handled first.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 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 350-401 exam.