- A
Apply a PodSecurityPolicy that restricts containers from running as root.
Why wrong: PSP is deprecated and replaced by Pod Security Admission; also it does not prevent token mounting.
- B
Create a new service account with no roles bound and assign it to the pod.
Why wrong: The pod would still use the default SA if not explicitly set, and the new SA without roles still has no access but does not prevent mounting of the default SA token.
- C
Edit the default service account to set automountServiceAccountToken: false.
Prevents automatic mounting of the default SA token in pods that do not specify a service account.
- D
Set automountServiceAccountToken: false in the pod spec.
Why wrong: This only affects that pod, not the default SA, and the question asks for measures to harden the cluster globally.
- E
Add securityContext: runAsNonRoot: true to the pod spec.
Ensures the container runs as a non-root user, reducing impact of compromise.
CKS Cluster Setup and Hardening Practice Question
This CKS practice question tests your understanding of cluster setup and hardening. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
During a security audit, you discover that a container running as root inside a pod has been compromised. The pod uses the default service account. Which two measures should you implement to harden the cluster? (Select TWO)
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
Edit the default service account to set automountServiceAccountToken: false.
Option C is correct because setting `automountServiceAccountToken: false` on the default service account prevents any pod that uses it from automatically mounting the service account token. This reduces the attack surface: if a container is compromised, the attacker cannot use the token to authenticate to the Kubernetes API server. This is a fundamental hardening measure for service accounts that do not require API access.
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.
- ✗
Apply a PodSecurityPolicy that restricts containers from running as root.
Why it's wrong here
PSP is deprecated and replaced by Pod Security Admission; also it does not prevent token mounting.
- ✗
Create a new service account with no roles bound and assign it to the pod.
Why it's wrong here
The pod would still use the default SA if not explicitly set, and the new SA without roles still has no access but does not prevent mounting of the default SA token.
- ✓
Edit the default service account to set automountServiceAccountToken: false.
Why this is correct
Prevents automatic mounting of the default SA token in pods that do not specify a service account.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Set automountServiceAccountToken: false in the pod spec.
Why it's wrong here
This only affects that pod, not the default SA, and the question asks for measures to harden the cluster globally.
- ✓
Add securityContext: runAsNonRoot: true to the pod spec.
Why this is correct
Ensures the container runs as a non-root user, reducing impact of compromise.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the distinction between disabling token mounting at the service account level versus the pod spec level, and candidates may incorrectly think that creating a new service account with no roles is sufficient, overlooking that the token itself is still mounted and could be used for reconnaissance or privilege escalation even without bound roles.
Detailed technical explanation
How to think about this question
The default service account in every namespace has a token secret mounted into pods at `/var/run/secrets/kubernetes.io/serviceaccount/token`. This token is a JWT that can be used to authenticate to the Kubernetes API server. By setting `automountServiceAccountToken: false` at the service account level (option C), all pods using that service account will not automatically mount the token. Additionally, setting `securityContext.runAsNonRoot: true` (option E) enforces that the container cannot run as UID 0, which is a critical control to limit the impact of a container escape. Under the hood, the `runAsNonRoot` field is validated by the kubelet's Pod Security Standards (Restricted profile) and prevents the container from starting if the image runs as root.
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 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
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.
- →
Cluster Setup and Hardening — study guide chapter
Learn the concepts, then practise the questions
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Cluster Setup and Hardening practice questions
Targeted practice on this topic area only
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Certified Kubernetes Security Specialist CKS study guide
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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 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Edit the default service account to set automountServiceAccountToken: false. — Option C is correct because setting `automountServiceAccountToken: false` on the default service account prevents any pod that uses it from automatically mounting the service account token. This reduces the attack surface: if a container is compromised, the attacker cannot use the token to authenticate to the Kubernetes API server. This is a fundamental hardening measure for service accounts that do not require API access.
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 →
Last reviewed: Jun 30, 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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