This CKS practice question tests your understanding of cluster setup and hardening. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 recommended practices for hardening RBAC in a Kubernetes cluster? (Select 3)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Regularly audit ClusterRoleBindings and RoleBindings for over-privileged subjects.
Option B is correct because regular auditing of ClusterRoleBindings and RoleBindings helps identify over-privileged subjects, such as service accounts or users with excessive permissions, which is a key hardening practice. This aligns with the principle of least privilege and is recommended by Kubernetes security best practices to reduce the attack surface.
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 the default service account in each namespace with cluster-admin.
Why it's wrong here
Default service accounts should not have elevated permissions.
✓
Regularly audit ClusterRoleBindings and RoleBindings for over-privileged subjects.
Why this is correct
Auditing helps identify and reduce excessive permissions.
Related concept
Read the scenario before looking for a memorised answer.
✓
Grant only the minimum permissions necessary for each subject.
Why this is correct
Least privilege is a core RBAC principle.
Related concept
Read the scenario before looking for a memorised answer.
✓
Avoid binding cluster-admin to service accounts unless absolutely necessary.
Why this is correct
Cluster-admin grants full cluster access and should be reserved for break-glass scenarios.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use RoleBindings with ClusterRoles in the same namespace to increase security.
Why it's wrong here
This is not a hardening practice; it is a normal RBAC usage.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that using RoleBindings with ClusterRoles is always more secure, but the trap here is that ClusterRoles can contain cluster-scoped permissions that are not namespace-restricted, potentially granting broader access than intended if not carefully reviewed.
Detailed technical explanation
How to think about this question
Under the hood, RBAC in Kubernetes uses RoleBinding objects to bind a Role (namespace-scoped) or ClusterRole (cluster-scoped) to subjects like users or service accounts. A common subtlety is that binding a ClusterRole via a RoleBinding only grants permissions for resources within that namespace, but the ClusterRole itself may include permissions for cluster-scoped resources (e.g., nodes), which are ignored in a RoleBinding—this can cause confusion during audits. In real-world scenarios, misconfigurations like binding a ClusterRole with node access via a RoleBinding can lead to unexpected access if the subject later gains cluster-scope 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: Regularly audit ClusterRoleBindings and RoleBindings for over-privileged subjects. — Option B is correct because regular auditing of ClusterRoleBindings and RoleBindings helps identify over-privileged subjects, such as service accounts or users with excessive permissions, which is a key hardening practice. This aligns with the principle of least privilege and is recommended by Kubernetes security best practices to reduce the attack surface.
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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Question Discussion
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