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. 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.
Which THREE of the following are best practices for RBAC hardening in Kubernetes? (Select THREE)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Avoid using the cluster-admin ClusterRole for service accounts
Option A is correct because the cluster-admin ClusterRole grants unrestricted access to all Kubernetes resources across all namespaces, which violates the principle of least privilege. Service accounts should be assigned only the specific permissions required for their function, not full administrative access. Using cluster-admin for service accounts increases the blast radius of a potential compromise and is a common misconfiguration that the CKS exam penalizes.
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.
✓
Avoid using the cluster-admin ClusterRole for service accounts
Why this is correct
Service accounts should have only the permissions they need.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Grant cluster-admin to all service accounts for simplicity
Why it's wrong here
This violates least privilege and is insecure.
✓
Apply the principle of least privilege when creating Roles and ClusterRoles
Why this is correct
Least privilege minimizes potential damage from compromised accounts.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use the default namespace for all service accounts
Why it's wrong here
Service accounts should be created in appropriate namespaces, not necessarily default.
✓
Regularly audit ClusterRoleBindings for excessive permissions
Why this is correct
Auditing helps identify and remove overly permissive bindings.
Clue confirmation
The clue word "best" in the question point toward this answer.
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 misconception that 'simplicity' (Option B) or 'using the default namespace' (Option D) are acceptable shortcuts, when in fact the CKS exam strictly enforces least privilege and namespace isolation as core hardening principles.
Detailed technical explanation
How to think about this question
Under the hood, RBAC in Kubernetes is enforced by the API server's authorization module (SubjectAccessReview), which evaluates every request against Role/ClusterRole rules. A ClusterRoleBinding with the cluster-admin ClusterRole binds to the 'system:masters' group, which bypasses normal RBAC checks entirely. In a real-world scenario, a compromised service account with cluster-admin could exfiltrate all secrets or deploy a malicious DaemonSet across nodes, making regular auditing of ClusterRoleBindings (Option E) critical for detecting such over-privileged bindings.
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.
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: Avoid using the cluster-admin ClusterRole for service accounts — Option A is correct because the cluster-admin ClusterRole grants unrestricted access to all Kubernetes resources across all namespaces, which violates the principle of least privilege. Service accounts should be assigned only the specific permissions required for their function, not full administrative access. Using cluster-admin for service accounts increases the blast radius of a potential compromise and is a common misconfiguration that the CKS exam penalizes.
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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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