Question 183 of 500
Automation and Quality of ServicehardMultiple ChoiceObjective-mapped

Quick Answer

The answer is that the script uses a single 'show running-config' without filtering, and the parser fails to locate QoS policies applied under interfaces. This occurs because pyATS parsers map CLI output to a structured data model, and an unfiltered 'show running-config' often does not recursively parse deeply nested sub-configurations like 'service-policy input/output' under interface sections. The parser sees the top-level config but misses the QoS policy-map bindings nested within interface blocks, causing false compliance reports even when misconfigurations exist. On the Cisco SPCOR 350-501 exam, this tests your understanding of automation tool limitations and the importance of targeted parsing—a common trap is assuming a full config dump captures all details. To avoid this, always use filtered commands like 'show running-config interface' or 'show policy-map interface' to ensure pyATS extracts the exact QoS hierarchy. Memory tip: "Unfiltered show run misses the nested fun"—always target the interface level for QoS validation.

350-501 Automation and Quality of Service Practice Question

This 350-501 practice question tests your understanding of automation and quality of service. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 automation engineer is writing a Python script using Cisco's pyATS library to validate QoS configurations across a fleet of routers. The script runs without errors but reports that all routers are compliant even though some are not. What is the most likely issue?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

  • Clue: "most likely"

    Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

Question 1hardmultiple choice
Study the full QoS 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 script uses a single 'show running-config' without filtering, and the parser fails to locate QoS policies applied under interfaces

Option C is correct because the pyATS parser for 'show running-config' without filtering may not recursively parse QoS policy-map configurations applied under interfaces. When the script uses a single unfiltered 'show running-config', the parser might fail to extract QoS policies nested under interface sub-configurations, leading to false compliance reports. This is a common issue where the parser's data model does not map deeply nested CLI structures like 'service-policy input/output' under interfaces.

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 pyATS library does not support QoS features for the specific platform

    Why it's wrong here

    pyATS supports a wide range of platforms, and if a parser exists, it would correctly interpret the data.

  • The testbed credentials are incorrect but the script still returns compliant

    Why it's wrong here

    Incorrect credentials would cause connection errors or authentication failures, not false compliance.

  • The script uses a single 'show running-config' without filtering, and the parser fails to locate QoS policies applied under interfaces

    Why this is correct

    A generic 'show run' parser may not extract nested configurations like interface service-policies, leading to false compliance.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    Read the scenario before looking for a memorised answer.

  • The script is parsing the startup-config instead of running-config

    Why it's wrong here

    If it parsed startup-config, changes not saved would be missed, but the script would still detect the current config only if it matches.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the misconception that a generic 'show running-config' parser will capture all configuration details, when in reality, nested or interface-specific constructs require targeted parsing or explicit iteration.

Detailed technical explanation

How to think about this question

pyATS/Genie parsers use a YANG-like data model to map CLI output to structured data. For QoS, the 'show running-config' output must be parsed with the correct parser (e.g., 'show running-config | section policy-map') to capture nested interface-level policies. Without filtering, the parser may only capture top-level constructs like 'policy-map' definitions but miss the 'service-policy' statements under interfaces, leading to false compliance. In real-world automation, engineers must use targeted parsers or iterate over interfaces to validate QoS bindings.

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.

Related practice questions

Related 350-501 practice-question pages

Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.

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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 script uses a single 'show running-config' without filtering, and the parser fails to locate QoS policies applied under interfaces — Option C is correct because the pyATS parser for 'show running-config' without filtering may not recursively parse QoS policy-map configurations applied under interfaces. When the script uses a single unfiltered 'show running-config', the parser might fail to extract QoS policies nested under interface sub-configurations, leading to false compliance reports. This is a common issue where the parser's data model does not map deeply nested CLI structures like 'service-policy input/output' under interfaces.

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.

Are there clue words in this question I should notice?

Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.

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

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