This CKS practice question tests your understanding of system hardening. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 security team is hardening a Kubernetes cluster. They need to ensure that all control plane components run with the least privilege. Which approach should they take?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "least"
Why it matters: You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure control plane containers to run as non-root user and with read-only root filesystem
Option C is correct because running control plane containers as a non-root user and with a read-only root filesystem directly enforces the principle of least privilege at the container level. This approach limits the ability of an attacker who compromises a control plane component to escalate privileges or modify critical system files, which is a fundamental hardening requirement for the control plane.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Use seccomp profiles to block privilege escalation syscalls
Why it's wrong here
Seccomp restricts system calls but does not change the user the container runs as.
✗
Apply AppArmor profiles to all control plane pods
Why it's wrong here
AppArmor profiles restrict specific programs, but not the user context of the container.
✓
Configure control plane containers to run as non-root user and with read-only root filesystem
Why this is correct
This directly reduces privileges by avoiding root execution and preventing writes to the filesystem.
Clue confirmation
The clue word "least" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable PodSecurityPolicy with 'MustRunAsNonRoot' for control plane namespaces
Why it's wrong here
PodSecurityPolicy is deprecated in Kubernetes 1.21+ and removed in 1.25. Also, it does not enforce read-only filesystem.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between runtime security mechanisms (seccomp, AppArmor) and container-level privilege controls (user ID, read-only filesystem), leading candidates to choose a syscall or MAC profile instead of the direct least-privilege configuration.
Detailed technical explanation
How to think about this question
Under the hood, running a container as a non-root user requires setting `securityContext.runAsUser` to a non-zero UID and `securityContext.readOnlyRootFilesystem: true` in the pod spec, which forces the container's root filesystem to be mounted read-only, preventing writes to `/`, `/etc`, `/bin`, etc. This is especially critical for control plane components like kube-apiserver and etcd, which often run with high privileges by default; a real-world scenario is a supply-chain attack where a compromised image tries to write a malicious binary to `/usr/bin` — a read-only root filesystem blocks that entirely.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CKS question in full detail.
System Hardening — This question tests System Hardening — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Configure control plane containers to run as non-root user and with read-only root filesystem — Option C is correct because running control plane containers as a non-root user and with a read-only root filesystem directly enforces the principle of least privilege at the container level. This approach limits the ability of an attacker who compromises a control plane component to escalate privileges or modify critical system files, which is a fundamental hardening requirement for the control plane.
What should I do if I get this CKS question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "least". You want the option with minimum overhead, fewest steps, or lowest impact — not the most feature-rich or comprehensive answer.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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