- A
--authorization-mode=Webhook
The --authorization-mode=Webhook flag on the kubelet enables external authorization for kubelet requests. While it can limit what actions are authorized, it does not specifically restrict the kubelet's ability to modify node status and pods. The dedicated mechanism is the NodeRestriction admission plugin on the API server.
- B
--read-only-port=0
Why wrong: The --read-only-port=0 flag disables the read-only port on the kubelet, which helps reduce attack surface but does not restrict the kubelet's ability to modify node status and pods.
- C
--protect-kernel-defaults=true
Why wrong: The --protect-kernel-defaults=true flag ensures that kernel parameters are set to secure defaults, but it does not restrict modifications to node status or pods.
- D
--authentication-token-webhook=true
Why wrong: The --authentication-token-webhook=true flag enables token review via webhook for authentication, not authorization or restriction of modifications.
Kubelet Authorization Mode Webhook: Restrict Node and Pod Modifications
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. A key principle to apply: nodeRestriction admission plugin. 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.
Which flag is used to restrict the kubelet's ability to modify node status and pods?
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
--authorization-mode=Webhook
The --authorization-mode=Webhook flag on the kubelet enables external authorization via a webhook. When configured with an appropriate webhook (e.g., one implementing NodeRestriction logic), it restricts the kubelet to only modify its own node and its assigned pods. This is the correct kubelet flag for the purpose.
Key principle: NodeRestriction admission plugin
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
--authorization-mode=Webhook
Why this is correct
The --authorization-mode=Webhook flag on the kubelet enables external authorization for kubelet requests. While it can limit what actions are authorized, it does not specifically restrict the kubelet's ability to modify node status and pods. The dedicated mechanism is the NodeRestriction admission plugin on the API server.
Related concept
NodeRestriction admission plugin
- ✗
--read-only-port=0
Why it's wrong here
The --read-only-port=0 flag disables the read-only port on the kubelet, which helps reduce attack surface but does not restrict the kubelet's ability to modify node status and pods.
- ✗
--protect-kernel-defaults=true
Why it's wrong here
The --protect-kernel-defaults=true flag ensures that kernel parameters are set to secure defaults, but it does not restrict modifications to node status or pods.
- ✗
--authentication-token-webhook=true
Why it's wrong here
The --authentication-token-webhook=true flag enables token review via webhook for authentication, not authorization or restriction of modifications.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates often confuse admission plugins (like NodeRestriction) with kubelet flags. While NodeRestriction runs on the API server, the kubelet flag --authorization-mode=Webhook enforces external authorization on the kubelet, which can achieve similar restrictions.
Detailed technical explanation
How to think about this question
Under the hood, when `--authorization-mode=Webhook` is set, the kubelet sends a SubjectAccessReview to the API server for every request it receives (including its own self-updates to node status). The webhook can be configured to deny the kubelet from modifying its node status unless explicitly allowed, which is critical in multi-tenant clusters where a compromised kubelet should not be able to falsely report node health or evict pods. A subtle behavior is that this flag only applies to the kubelet's authorization for incoming requests, not to its outbound calls to the API server for heartbeats or pod updates—those are governed by the kubelet's own credentials and RBAC.
KKey Concepts to Remember
- NodeRestriction admission plugin
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
NodeRestriction admission plugin
Real-world example
How this comes up in practice
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
What to study next
Got this wrong? Here's your next step.
Review nodeRestriction admission plugin, then practise related CKS questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this CKS question test?
Cluster Setup and Hardening — This question tests Cluster Setup and Hardening — NodeRestriction admission plugin.
What is the correct answer to this question?
The correct answer is: --authorization-mode=Webhook — The --authorization-mode=Webhook flag on the kubelet enables external authorization via a webhook. When configured with an appropriate webhook (e.g., one implementing NodeRestriction logic), it restricts the kubelet to only modify its own node and its assigned pods. This is the correct kubelet flag for the purpose.
What should I do if I get this CKS question wrong?
Review nodeRestriction admission plugin, then practise related CKS questions on the same topic to reinforce the concept.
What is the key concept behind this question?
NodeRestriction admission plugin
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Last reviewed: Jun 24, 2026
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