- A
The automation script used RESTCONF which requires a commit to finalize
Why wrong: RESTCONF commits immediately; if rollback was performed, it would have undone the change.
- B
The device requires a reload to clear the old marking
Why wrong: Cisco IOS does not require a reload to clear marking changes; removal of the policy is immediate.
- C
The rollback script only applied to the outbound direction
Why wrong: The original change was inbound, so the rollback script likely targeted the inbound direction; the problem is likely outbound.
- D
The rolled back policy was applied inbound, but the outbound policy that also applies marking was not rolled back
The automation may have only rolled back the inbound policy, leaving the outbound marking policy active, which continues to mark traffic.
Quick Answer
The answer is that the rolled back policy was applied inbound, but the outbound policy that also applies marking was not rolled back. This is correct because QoS policies are applied independently per direction on an interface; a rollback of an inbound marking policy does not automatically revert any separate outbound marking policy that may have been configured earlier or as part of the same automation script. On the Cisco SPCOR / CCNP Service Provider Core 350-501 exam, this scenario tests your understanding of directional QoS application and the common trap of assuming a rollback is comprehensive—candidates often forget that outbound policies remain active unless explicitly reverted. A useful memory tip is “inbound rollback, outbound still on track,” reminding you that each direction’s policy must be verified independently during troubleshooting.
350-501 Automation and Quality of Service Practice Question
This 350-501 practice question tests your understanding of automation and quality of service. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
During a maintenance window, an automation script pushed a QoS policy that inadvertently changed the marking for all inbound traffic on a core interface. The change was rolled back, but performance reports show that some traffic is still being marked incorrectly. What is the most logical explanation?
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
The rolled back policy was applied inbound, but the outbound policy that also applies marking was not rolled back
Option D is correct because QoS policies can be applied independently in the inbound and outbound directions on an interface. If the original automation script modified the inbound marking policy, and the rollback only reverted that inbound policy, any outbound policy that also performs marking would remain unchanged and continue to incorrectly mark traffic. This explains why some traffic still shows incorrect marking after the rollback.
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 automation script used RESTCONF which requires a commit to finalize
Why it's wrong here
RESTCONF commits immediately; if rollback was performed, it would have undone the change.
- ✗
The device requires a reload to clear the old marking
Why it's wrong here
Cisco IOS does not require a reload to clear marking changes; removal of the policy is immediate.
- ✗
The rollback script only applied to the outbound direction
Why it's wrong here
The original change was inbound, so the rollback script likely targeted the inbound direction; the problem is likely outbound.
- ✓
The rolled back policy was applied inbound, but the outbound policy that also applies marking was not rolled back
Why this is correct
The automation may have only rolled back the inbound policy, leaving the outbound marking policy active, which continues to mark traffic.
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 concept that QoS policies are directional and that a rollback must consider both inbound and outbound policies independently, leading candidates to overlook the possibility of a separate outbound marking policy still being active.
Detailed technical explanation
How to think about this question
In Cisco IOS, QoS policies are configured using the 'service-policy input' and 'service-policy output' commands under an interface, and each direction maintains its own policy-map and class-map hierarchy. When a rollback script only removes or reverts the inbound policy, any outbound policy that also contains a 'set dscp' or 'set precedence' action continues to apply its marking to traffic exiting the interface. This is a common oversight in automation scripts that assume a single policy direction controls all marking.
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 small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
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.
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Automation and Quality of Service — study guide chapter
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FAQ
Questions learners often ask
What does this 350-501 question test?
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: The rolled back policy was applied inbound, but the outbound policy that also applies marking was not rolled back — Option D is correct because QoS policies can be applied independently in the inbound and outbound directions on an interface. If the original automation script modified the inbound marking policy, and the rollback only reverted that inbound policy, any outbound policy that also performs marking would remain unchanged and continue to incorrectly mark traffic. This explains why some traffic still shows incorrect marking after the rollback.
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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Last reviewed: Jun 25, 2026
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.
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