- A
privileged: false
Why wrong: This ensures the container is not privileged, but does not make the filesystem read-only.
- B
readOnlyRootFilesystem: true
This is the correct field to set the root filesystem read-only.
- C
readOnly: true
Why wrong: There is no such field in SecurityContext.
- D
allowPrivilegeEscalation: false
Why wrong: This prevents privilege escalation, not read-only filesystem.
Question 76 of 997
How to Enforce Read-Only Root Filesystem in Pod Security Context
This CKS practice question tests your understanding of monitoring, logging and runtime security. 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 cluster administrator wants to enforce that containers run with a read-only root filesystem. Which security context field should be set?
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
✓
readOnlyRootFilesystem: true
Option B is correct because the `readOnlyRootFilesystem: true` field in the Pod or container security context explicitly mounts the container's root filesystem as read-only, preventing any writes to the filesystem. This is a key runtime security control to mitigate malware or unauthorized modifications, as required by the CIS Kubernetes Benchmark and common security policies.
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.
- ✗
privileged: false
Why it's wrong here
This ensures the container is not privileged, but does not make the filesystem read-only.
- ✓
readOnlyRootFilesystem: true
Why this is correct
This is the correct field to set the root filesystem read-only.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
readOnly: true
Why it's wrong here
There is no such field in SecurityContext.
- ✗
allowPrivilegeEscalation: false
Why it's wrong here
This prevents privilege escalation, not read-only filesystem.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The CKS exam often tests the distinction between `readOnlyRootFilesystem` and the non-existent `readOnly` field, exploiting the common misconception that a simple `readOnly` boolean exists in the security context.
Detailed technical explanation
How to think about this question
The `readOnlyRootFilesystem` field is part of the `SecurityContext` under `containers[].securityContext` or `pod.spec.securityContext`. When set to `true`, Kubernetes mounts the root filesystem as read-only using the `ro` mount option in the container's mount namespace, but allows writes to emptyDir volumes or other explicitly mounted writable volumes. This is critical for compliance with Pod Security Standards (PSS) 'Restricted' profile and for preventing runtime attacks like cryptominers writing to disk.
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.
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FAQ
Questions learners often ask
What does this CKS question test?
Monitoring, Logging and Runtime Security — This question tests Monitoring, Logging and Runtime Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: readOnlyRootFilesystem: true — Option B is correct because the `readOnlyRootFilesystem: true` field in the Pod or container security context explicitly mounts the container's root filesystem as read-only, preventing any writes to the filesystem. This is a key runtime security control to mitigate malware or unauthorized modifications, as required by the CIS Kubernetes Benchmark and common security policies.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on CKS
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An administrator wants to ensure that containers in the 'secure-app' namespace cannot write to their own filesystem. Which pod security context setting should be used?
medium- A.securityContext: { runAsNonRoot: true }
- B.securityContext: { privileged: false }
- C.securityContext: { capabilities: { drop: ["ALL"] } }
- ✓ D.securityContext: { readOnlyRootFilesystem: true }
Why D: Immutable container filesystem is achieved by setting readOnlyRootFilesystem: true in the securityContext of the container. This prevents writes to the root filesystem.
Keep practising
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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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