This CKS practice question tests your understanding of system hardening. 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.
A cluster uses a custom mutating admission webhook that adds a sidecar container to all pods. After an upgrade, the webhook crashes and pods cannot be created. What is the best way to prevent this scenario in future?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Run multiple replicas of the webhook
Why wrong: All replicas could crash simultaneously.
Set the webhook's failurePolicy to Ignore
Allows pod creation to proceed if webhook is unavailable.
Disable admission webhooks in the cluster
Why wrong: Would break other features.
Create a validating webhook as a backup
Why wrong: Validating webhooks also block if they fail.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Set the webhook's failurePolicy to Ignore
Setting the webhook's failurePolicy to Ignore ensures that if the webhook fails (e.g., crashes or times out), the API server will bypass the webhook and allow the pod creation to proceed. This prevents a single point of failure from blocking all pod creation, which is critical for cluster availability. The default failurePolicy is Fail, which would cause the entire admission request to fail if the webhook is unreachable.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Run multiple replicas of the webhook
Why it's wrong here
All replicas could crash simultaneously.
Set the webhook's failurePolicy to Ignore
Why this is correct
Allows pod creation to proceed if webhook is unavailable.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Disable admission webhooks in the cluster
Why it's wrong here
Would break other features.
Create a validating webhook as a backup
Why it's wrong here
Validating webhooks also block if they fail.
Common exam traps
The trap here is that candidates often think high availability (multiple replicas) is sufficient, but the CKS exam tests the understanding that failurePolicy is the direct mechanism to prevent a single webhook failure from blocking all pod creation, regardless of replica count.
Detailed technical explanation
The failurePolicy field in a MutatingWebhookConfiguration or ValidatingWebhookConfiguration can be set to either 'Fail' (default) or 'Ignore'. When set to 'Ignore', the API server will skip the webhook call if it cannot reach the webhook endpoint (e.g., due to timeout or DNS failure) and proceed with the admission request. This is especially important for mutating webhooks that add sidecars, as a crash can otherwise cause a denial-of-service condition where no new pods can be created. In practice, you should also implement proper monitoring and alerting on webhook failures even with failurePolicy: Ignore, so that you are aware of the degraded state.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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
System Hardening — This question tests System Hardening — Read the scenario before looking for a memorised answer..
The correct answer is: Set the webhook's failurePolicy to Ignore — Setting the webhook's failurePolicy to Ignore ensures that if the webhook fails (e.g., crashes or times out), the API server will bypass the webhook and allow the pod creation to proceed. This prevents a single point of failure from blocking all pod creation, which is critical for cluster availability. The default failurePolicy is Fail, which would cause the entire admission request to fail if the webhook is unreachable.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
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.
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