- A
Use the MQC framework to classify traffic based on DSCP markings, apply a priority queue for EF traffic, and allocate a minimum bandwidth guarantee for AF41 traffic.
This correctly implements DiffServ with consistent PHB: priority for voice (EF) and bandwidth guarantee for video (AF41) using MQC.
- B
Implement a single FIFO queue on all interfaces and rely on the default CoS-to-queue mapping to prioritize voice.
Why wrong: FIFO does not provide differentiated treatment; voice and video would compete with data, causing jitter and loss.
- C
Configure strict priority queuing for all traffic marked with DSCP values greater than 0.
Why wrong: This would prioritize all marked traffic, including bulk data, starving other traffic and not guaranteeing bandwidth for video.
- D
Use the IntServ model with RSVP to reserve bandwidth for each voice and video flow.
Why wrong: IntServ is not scalable for large campus networks and is not the DiffServ model required by the scenario.
Quick Answer
The correct approach is to use the Modular QoS CLI (MQC) framework to classify traffic by DSCP markings, apply a strict priority queue for EF (DSCP 46) voice traffic, and allocate a minimum bandwidth guarantee for AF41 (DSCP 34) video traffic. This works because DiffServ relies on consistent per-hop behavior, and MQC enforces that by mapping DSCP values to specific queuing actions: priority queuing gives voice the low-latency treatment it requires, while a minimum bandwidth reservation for AF41 ensures video gets a guaranteed share without starving other classes, as AF uses weighted fair queuing. On the ENCOR 350-401 exam, this question tests your ability to design a DiffServ QoS policy that balances real-time traffic with mission-critical data—a common trap is confusing priority queuing for video, which can starve other flows, or forgetting that EF must be strictly prioritized while AF needs a bandwidth guarantee. Remember the mnemonic: “Voice is Priority, Video is Assured—EF gets the fast lane, AF41 gets its share.”
350-401 QoS Architecture Practice Question
This 350-401 practice question tests your understanding of qos architecture. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An architect is designing a QoS policy for a campus LAN that must support real-time voice and video traffic alongside mission-critical data. The design must use the DiffServ model with consistent per-hop behavior across all switches. Which approach should the architect choose to ensure that voice traffic receives priority queuing while video traffic is guaranteed bandwidth without starving other classes?
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
Use the MQC framework to classify traffic based on DSCP markings, apply a priority queue for EF traffic, and allocate a minimum bandwidth guarantee for AF41 traffic.
Option A is correct because it uses the Modular QoS CLI (MQC) framework to classify traffic by DSCP markings, which aligns with the DiffServ model's per-hop behavior consistency. By applying a strict priority queue for EF (Expedited Forwarding, DSCP 46) traffic, voice gets low-latency treatment, while a minimum bandwidth guarantee for AF41 (Assured Forwarding, DSCP 34) ensures video traffic receives a guaranteed share without starving other classes, as AF uses weighted fair queuing with bandwidth allocation.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Use the MQC framework to classify traffic based on DSCP markings, apply a priority queue for EF traffic, and allocate a minimum bandwidth guarantee for AF41 traffic.
Why this is correct
This correctly implements DiffServ with consistent PHB: priority for voice (EF) and bandwidth guarantee for video (AF41) using MQC.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Implement a single FIFO queue on all interfaces and rely on the default CoS-to-queue mapping to prioritize voice.
Why it's wrong here
FIFO does not provide differentiated treatment; voice and video would compete with data, causing jitter and loss.
- ✗
Configure strict priority queuing for all traffic marked with DSCP values greater than 0.
Why it's wrong here
This would prioritize all marked traffic, including bulk data, starving other traffic and not guaranteeing bandwidth for video.
- ✗
Use the IntServ model with RSVP to reserve bandwidth for each voice and video flow.
Why it's wrong here
IntServ is not scalable for large campus networks and is not the DiffServ model required by the scenario.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that strict priority queuing can be applied broadly to multiple traffic classes without starvation risks, but the trap here is that only EF (voice) should use priority queuing, while AF (video) requires a bandwidth guarantee to avoid starving other classes.
Trap categories for this question
Scenario analysis trap
IntServ is not scalable for large campus networks and is not the DiffServ model required by the scenario.
Detailed technical explanation
How to think about this question
Under the hood, the MQC uses class maps to match DSCP values (e.g., EF for voice, AF41 for video) and policy maps to apply actions like priority (which assigns a strict priority queue with policer to prevent starvation) and bandwidth (which uses CBWFQ to guarantee a minimum percentage). In real-world deployments, the priority queue for EF should be policed (e.g., to 30% of link bandwidth) to prevent voice from overwhelming other traffic, while AF41's bandwidth guarantee ensures video throughput without preempting best-effort data.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 350-401 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Questions learners often ask
What does this 350-401 question test?
QoS Architecture — This question tests QoS Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use the MQC framework to classify traffic based on DSCP markings, apply a priority queue for EF traffic, and allocate a minimum bandwidth guarantee for AF41 traffic. — Option A is correct because it uses the Modular QoS CLI (MQC) framework to classify traffic by DSCP markings, which aligns with the DiffServ model's per-hop behavior consistency. By applying a strict priority queue for EF (Expedited Forwarding, DSCP 46) traffic, voice gets low-latency treatment, while a minimum bandwidth guarantee for AF41 (Assured Forwarding, DSCP 34) ensures video traffic receives a guaranteed share without starving other classes, as AF uses weighted fair queuing with bandwidth allocation.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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