- A
Use a NetworkPolicy to restrict filesystem access
Why wrong: NetworkPolicy controls network traffic, not filesystem permissions.
- B
Run the pod with securityContext.readOnlyRootFilesystem: true
Setting readOnlyRootFilesystem: true in the security context makes the root filesystem read-only. This is a Pod-level setting.
- C
Set securityContext.runAsNonRoot: true
Why wrong: runAsNonRoot ensures the container runs as a non-root user, but does not affect filesystem write permissions.
- D
Set securityContext.allowPrivilegeEscalation: false
Why wrong: allowPrivilegeEscalation prevents privilege escalation but does not make the root filesystem read-only.
Question 70 of 997
Pod Read-Only Root Filesystem Security Context
This CKS practice question tests your understanding of minimize microservice vulnerabilities. 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.
An administrator needs to enforce that all pods in a namespace run with read-only root filesystem. Which Pod Security Standard should be applied?
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
✓
Run the pod with securityContext.readOnlyRootFilesystem: true
Option B is correct because setting `securityContext.readOnlyRootFilesystem: true` at the pod or container level enforces that the container's root filesystem is mounted as read-only, preventing any writes to the root filesystem. This directly satisfies the requirement to run all pods in the namespace with a read-only root filesystem, which is a key control for minimizing the impact of a compromise by limiting write access to the container's base image.
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 a NetworkPolicy to restrict filesystem access
Why it's wrong here
NetworkPolicy controls network traffic, not filesystem permissions.
- ✓
Run the pod with securityContext.readOnlyRootFilesystem: true
Why this is correct
Setting readOnlyRootFilesystem: true in the security context makes the root filesystem read-only. This is a Pod-level setting.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set securityContext.runAsNonRoot: true
Why it's wrong here
runAsNonRoot ensures the container runs as a non-root user, but does not affect filesystem write permissions.
- ✗
Set securityContext.allowPrivilegeEscalation: false
Why it's wrong here
allowPrivilegeEscalation prevents privilege escalation but does not make the root filesystem read-only.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CKS exam often tests the distinction between security contexts that control user identity (runAsNonRoot), privilege escalation (allowPrivilegeEscalation), and filesystem write permissions (readOnlyRootFilesystem), leading candidates to confuse non-root execution with filesystem write protection.
Detailed technical explanation
How to think about this question
Under the hood, `readOnlyRootFilesystem: true` leverages Linux kernel mount flags (specifically `MS_RDONLY`) to remount the container's root filesystem as read-only after the container is started. This means that even if a process gains root privileges inside the container, it cannot modify system binaries, configuration files, or libraries in the root filesystem, forcing all writes to explicitly mounted volumes (e.g., emptyDir or PersistentVolumeClaim). In a real-world scenario, this is critical for immutable infrastructure patterns where containers should be treated as ephemeral and any state must be externalized, reducing the attack surface for persistent malware or configuration tampering.
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.
What to study next
Got this wrong? Here's your next step.
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
Questions learners often ask
What does this CKS question test?
Minimize Microservice Vulnerabilities — This question tests Minimize Microservice Vulnerabilities — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Run the pod with securityContext.readOnlyRootFilesystem: true — Option B is correct because setting `securityContext.readOnlyRootFilesystem: true` at the pod or container level enforces that the container's root filesystem is mounted as read-only, preventing any writes to the root filesystem. This directly satisfies the requirement to run all pods in the namespace with a read-only root filesystem, which is a key control for minimizing the impact of a compromise by limiting write access to the container's base image.
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.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 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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