CKS Minimize Microservice Vulnerabilities Practice Question
A cluster has a ValidatingWebhookConfiguration that intercepts Pod CREATE requests. The webhook server is unavailable. What happens when a user tries to create a pod?
⚠ Common exam trap
The CKS exam often tests the default `failurePolicy` behavior, and the trap here is that candidates assume the API server will simply skip validation or crash, rather than understanding that the default `Fail` policy causes the request to be rejected.
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 pod creation is rejected until the webhook becomes available
When a ValidatingWebhookConfiguration is defined and the webhook server is unavailable, the default failure policy is `Fail`, which causes the API server to reject the Pod CREATE request. This ensures that security validation is not bypassed due to webhook downtime, maintaining the cluster's security posture. The pod creation is blocked until the webhook becomes available again, as specified by the `failurePolicy` field in the webhook configuration.
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 automatically disabled
Why it's wrong here
A webhook is never auto-disabled when its server is unreachable; the ValidatingWebhookConfiguration persists and keeps intercepting matching requests. Automatic disabling would silently remove admission control, which Kubernetes deliberately avoids. Only an administrator can delete or amend the configuration.
- ✗
The API server crashes
Why it's wrong here
The API server does not crash; it simply cannot obtain a validation decision and returns an error for the pod CREATE request. Failure policy governs this behaviour. Crashing would require a separate fault, and the webhook call is isolated from the API server process.
- ✓
The pod creation is rejected until the webhook becomes available
Why this is correct
A ValidatingWebhookConfiguration with failurePolicy set to Fail rejects requests when the webhook server cannot be reached. Because the webhook intercepts Pod CREATE, admission fails closed, so the pod creation is rejected until the server recovers.
- ✗
The pod is created without webhook validation
Why it's wrong here
The pod is not created; admission fails because the API server cannot reach the webhook server to obtain a validation response. With failurePolicy set to Fail, the request is rejected. Creating without validation would occur only if failurePolicy were Ignore.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CKS practice question is part of Courseiva's free CNCF 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 CKS exam.