Question 512 of 997

Minimize Microservice Vulnerabilities →mediumMultiple ChoiceObjective-mapped

Troubleshooting ValidatingWebhookConfiguration: Service Unreachable

This CKS practice question tests your understanding of minimize microservice vulnerabilities. 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.

You have created a ValidatingWebhookConfiguration to reject pods without resource limits. When you try to create a pod without limits, it is created successfully. What is the most likely reason?

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.

A
The webhook is not matching the namespace labels
Why wrong: If the webhook does not match the namespace, it would not intercept the request, but the question implies the webhook is intended to apply cluster-wide.
B
The webhook service is not running or is unreachable
If the webhook service is down, the API server will fail open (depending on failurePolicy) and allow the pod creation.
C
The webhook is configured with failurePolicy: Fail
Why wrong: failurePolicy: Fail would cause the API server to reject the request if the webhook cannot be reached.
D
The pod is being created by a controller like a Deployment
Why wrong: Webhooks apply to all API requests, regardless of the creator.

Full breakdown with real-world context →

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 webhook service is not running or is unreachable

The most likely reason a pod without resource limits is created successfully despite a ValidatingWebhookConfiguration is that the webhook service itself is not running or is unreachable. When the API server cannot contact the webhook endpoint, the default behavior (failurePolicy: Ignore) allows the request to proceed, so the pod is created without validation. If the webhook were functioning correctly, it would reject the pod; thus, the failure to reject indicates a connectivity or service issue.

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 webhook is not matching the namespace labels
Why it's wrong here
If the webhook does not match the namespace, it would not intercept the request, but the question implies the webhook is intended to apply cluster-wide.
✓
The webhook service is not running or is unreachable
Why this is correct
If the webhook service is down, the API server will fail open (depending on failurePolicy) and allow the pod creation.
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 webhook is configured with failurePolicy: Fail
Why it's wrong here
failurePolicy: Fail would cause the API server to reject the request if the webhook cannot be reached.
✗
The pod is being created by a controller like a Deployment
Why it's wrong here
Webhooks apply to all API requests, regardless of the creator.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Candidates may incorrectly assume the ValidatingWebhookConfiguration is misconfigured (e.g., missing objectSelector or wrong failurePolicy) when the actual issue is that the webhook backend service is unreachable. In Kubernetes, if the API server cannot reach the webhook server, the failurePolicy (default Ignore) allows the pod creation, so the pod passes through without validation. This is a common pitfall where the webhook service itself is not running or not accessible, rather than a configuration error.

Detailed technical explanation

How to think about this question

Under the hood, the API server makes an HTTPS POST request to the webhook service URL defined in the ValidatingWebhookConfiguration. If the service is not running, the connection times out or is refused, and the API server applies the failurePolicy — defaulting to Ignore if not explicitly set to Fail. In a real-world scenario, a misconfigured network policy, missing endpoints, or a crashed webhook pod can cause this silent bypass, making it critical to monitor webhook health and set failurePolicy: Fail for security-sensitive validations.

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 CKS 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.

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FAQ

Questions learners often ask

What does this CKS question test?

Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The webhook service is not running or is unreachable — The most likely reason a pod without resource limits is created successfully despite a ValidatingWebhookConfiguration is that the webhook service itself is not running or is unreachable. When the API server cannot contact the webhook endpoint, the default behavior (failurePolicy: Ignore) allows the request to proceed, so the pod is created without validation. If the webhook were functioning correctly, it would reject the pod; thus, the failure to reject indicates a connectivity or service issue.

What should I do if I get this CKS 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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