This CKS practice question tests your understanding of cluster setup and hardening. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
To protect kernel defaults on a node, which flag should be set on the kubelet?
--hardening=true
Why wrong: This flag does not exist.
--protect-kernel-defaults=true
This flag prevents the kubelet from modifying kernel parameters that could affect security.
--protect-kernel-parameters=true
Why wrong: The correct flag is --protect-kernel-defaults.
--kernel-security=true
Why wrong: This flag does not exist.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
--protect-kernel-defaults=true
The `--protect-kernel-defaults=true` flag on the kubelet ensures that the kubelet will not start if any kernel tunables (e.g., `vm.overcommit_memory`, `kernel.panic`) differ from their default values. This is a security hardening measure to prevent misconfigured nodes from running with weakened kernel settings, as required by the CIS Kubernetes Benchmark.
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.
--hardening=true
Why it's wrong here
This flag does not exist.
--protect-kernel-defaults=true
Why this is correct
This flag prevents the kubelet from modifying kernel parameters that could affect security.
Related concept
Read the scenario before looking for a memorised answer.
--protect-kernel-parameters=true
Why it's wrong here
The correct flag is --protect-kernel-defaults.
--kernel-security=true
Why it's wrong here
This flag does not exist.
Common exam traps
The trap here is that candidates confuse the exact flag name with plausible-sounding alternatives like 'protect-kernel-parameters' or 'kernel-security', but the CKS exam expects precise recall of the actual kubelet flag `--protect-kernel-defaults=true` as defined in the CIS Benchmark.
Detailed technical explanation
When `--protect-kernel-defaults=true` is set, the kubelet checks specific sysctl parameters (e.g., `vm.overcommit_memory`, `kernel.panic`, `kernel.panic_on_oops`) against their kernel defaults. If any parameter has been modified, the kubelet fails to start, preventing a node from running with insecure kernel settings. This is particularly important in multi-tenant clusters where a compromised container could exploit non-default kernel tunables to escalate privileges.
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
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FAQ
Cluster Setup and Hardening — This question tests Cluster Setup and Hardening — Read the scenario before looking for a memorised answer..
The correct answer is: --protect-kernel-defaults=true — The `--protect-kernel-defaults=true` flag on the kubelet ensures that the kubelet will not start if any kernel tunables (e.g., `vm.overcommit_memory`, `kernel.panic`) differ from their default values. This is a security hardening measure to prevent misconfigured nodes from running with weakened kernel settings, as required by the CIS Kubernetes Benchmark.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 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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