The correct answer is that voice traffic is guaranteed to be sent before any other traffic. This is because the priority queue, configured under the voice class, is serviced first by the scheduler, and only after that traffic is fully transmitted does the remaining bandwidth become available for the non-priority classes. The video class then uses the bandwidth remaining percent command to claim 30% of that leftover capacity, which is the standard CBWFQ behavior when a strict priority queue is present. On the Cisco SPCOR 350-501 exam, this concept often appears in a QoS exhibit where candidates must distinguish between absolute bandwidth guarantees and percentage-based allocation of leftover bandwidth. A common trap is confusing bandwidth remaining percent with the regular bandwidth percent command—the former only applies after priority traffic is served, while the latter guarantees a fixed share of the total link. Remember the mnemonic: “Priority first, leftovers split by percent.”
350-501 Automation and Quality of Service Practice Question
This 350-501 practice question tests your understanding of automation and quality of service. 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.
Exhibit
Refer to the exhibit.
class-map match-any VOICE
match ip dscp ef
class-map match-any VIDEO
match ip dscp af41 af42
class-map match-any DATA
match ip dscp default
!
policy-map QOS_POLICY
class VOICE
priority level 1
set mpls experimental topmost 5
class VIDEO
bandwidth remaining percent 30
set mpls experimental topmost 4
class DATA
bandwidth remaining percent 70
set mpls experimental topmost 0
!
interface GigabitEthernet0/0/0
service-policy output QOS_POLICY
Which TWO statements accurately describe the behavior of the QoS policy shown in the exhibit?
Refer to the exhibit.
class-map match-any VOICE
match ip dscp ef
class-map match-any VIDEO
match ip dscp af41 af42
class-map match-any DATA
match ip dscp default
!
policy-map QOS_POLICY
class VOICE
priority level 1
set mpls experimental topmost 5
class VIDEO
bandwidth remaining percent 30
set mpls experimental topmost 4
class DATA
bandwidth remaining percent 70
set mpls experimental topmost 0
!
interface GigabitEthernet0/0/0
service-policy output QOS_POLICY
A
The policy shapes the total output traffic to 30 Mbps.
Why wrong: No shaping command is present; the policy only manages queuing.
B
During congestion, video traffic is allocated 30% of the remaining bandwidth after voice is served.
Bandwidth remaining percent allocates a percentage of the available bandwidth after priority queues are serviced.
C
Video traffic is placed in a strict priority queue.
Why wrong: Video uses bandwidth remaining percent, not priority.
D
The policy polices voice traffic to a maximum of 30% of the interface bandwidth.
Why wrong: No police command is configured; the priority queue can consume all available bandwidth.
E
Voice traffic is guaranteed to be sent before any other traffic.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
During congestion, video traffic is allocated 30% of the remaining bandwidth after voice is served.
Option B is correct because the policy uses the 'bandwidth remaining percent' command under the video class, which allocates 30% of the remaining bandwidth after the voice class (which is in a strict priority queue) has been served. This is the standard behavior for class-based weighted fair queuing (CBWFQ) when a priority queue is present: the priority traffic is serviced first, and then the remaining bandwidth is distributed according to the 'bandwidth remaining percent' values assigned to the non-priority classes.
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.
✗
The policy shapes the total output traffic to 30 Mbps.
Why it's wrong here
No shaping command is present; the policy only manages queuing.
✓
During congestion, video traffic is allocated 30% of the remaining bandwidth after voice is served.
Why this is correct
Bandwidth remaining percent allocates a percentage of the available bandwidth after priority queues are serviced.
Related concept
Read the scenario before looking for a memorised answer.
✗
Video traffic is placed in a strict priority queue.
Why it's wrong here
Video uses bandwidth remaining percent, not priority.
✗
The policy polices voice traffic to a maximum of 30% of the interface bandwidth.
Why it's wrong here
No police command is configured; the priority queue can consume all available bandwidth.
✓
Voice traffic is guaranteed to be sent before any other traffic.
Why this is correct
Priority level 1 ensures voice is dequeued first.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between 'bandwidth' (which allocates a guaranteed minimum during congestion) and 'bandwidth remaining percent' (which allocates a percentage of leftover bandwidth after priority queues), and candidates frequently confuse 'police' with 'shape' or misinterpret a fixed police rate as a percentage of interface bandwidth.
Trap categories for this question
Command / output trap
No shaping command is present; the policy only manages queuing.
Detailed technical explanation
How to think about this question
Under the hood, the 'priority' command in a QoS policy map creates a low-latency queue (LLQ) that is serviced before any CBWFQ queues, ensuring voice traffic experiences minimal jitter and delay. The 'bandwidth remaining percent' command allocates a percentage of the link bandwidth that remains after the priority queue has been serviced, which is critical for ensuring video traffic gets a fair share without starving other data traffic. In a real-world scenario, if the priority queue consumes more than its allocated police rate (e.g., due to burst), the excess voice traffic is dropped, preventing it from starving the video and data queues.
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 350-501 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
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Automation and Quality of Service — This question tests Automation and Quality of Service — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: During congestion, video traffic is allocated 30% of the remaining bandwidth after voice is served. — Option B is correct because the policy uses the 'bandwidth remaining percent' command under the video class, which allocates 30% of the remaining bandwidth after the voice class (which is in a strict priority queue) has been served. This is the standard behavior for class-based weighted fair queuing (CBWFQ) when a priority queue is present: the priority traffic is serviced first, and then the remaining bandwidth is distributed according to the 'bandwidth remaining percent' values assigned to the non-priority classes.
What should I do if I get this 350-501 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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Question Discussion
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