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.
An administrator runs kube-bench on a cluster node and receives failures for CIS benchmark checks related to kubelet configuration. Which kubelet flag should be set to ensure that kernel defaults are not used when they might be insecure?
--protect-kernel-defaults
This flag is explicitly checked by kube-bench for CIS compliance.
--read-only-port=0
Why wrong: This disables the read-only port, but does not protect kernel defaults.
--anonymous-auth=false
Why wrong: This disables anonymous authentication, but not kernel defaults protection.
--kubelet-extra-args
Why wrong: This is a generic flag, not specific to kernel defaults.
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
The `--protect-kernel-defaults` kubelet flag ensures that the kubelet will not use insecure kernel defaults by enforcing that certain sysctl settings (e.g., `kernel.panic`, `vm.overcommit_memory`) are set to secure values. If these kernel parameters are not explicitly configured to safe values, the kubelet will fail to start, preventing the node from running with potentially insecure kernel defaults. This directly addresses CIS benchmark checks that require hardening of the kubelet's interaction with the host kernel.
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.
--protect-kernel-defaults
Why this is correct
This flag is explicitly checked by kube-bench for CIS compliance.
Related concept
Read the scenario before looking for a memorised answer.
--read-only-port=0
Why it's wrong here
This disables the read-only port, but does not protect kernel defaults.
--anonymous-auth=false
Why it's wrong here
This disables anonymous authentication, but not kernel defaults protection.
--kubelet-extra-args
Why it's wrong here
This is a generic flag, not specific to kernel defaults.
Common exam traps
The trap here is that candidates often confuse `--protect-kernel-defaults` with other kubelet security flags like `--read-only-port` or `--anonymous-auth`, or mistakenly think `--kubelet-extra-args` is a direct kubelet flag, when in fact it is a kubeadm configuration option and not a solution for kernel default protection.
Detailed technical explanation
Under the hood, `--protect-kernel-defaults` causes the kubelet to validate and enforce specific sysctl parameters defined in the Kubernetes source code, such as `vm.overcommit_memory` (must be 1) and `kernel.panic` (must be 10 or greater). In a real-world scenario, if a node has been configured with custom kernel settings that are insecure (e.g., `vm.overcommit_memory=0`), the kubelet will refuse to start unless the flag is set and the sysctls are corrected, preventing silent security gaps.
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 — The `--protect-kernel-defaults` kubelet flag ensures that the kubelet will not use insecure kernel defaults by enforcing that certain sysctl settings (e.g., `kernel.panic`, `vm.overcommit_memory`) are set to secure values. If these kernel parameters are not explicitly configured to safe values, the kubelet will fail to start, preventing the node from running with potentially insecure kernel defaults. This directly addresses CIS benchmark checks that require hardening of the kubelet's interaction with the host kernel.
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
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