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.
You run 'kubectl auth can-i --list --as=system:serviceaccount:kube-system:my-sa' and see that my-sa has cluster-admin access. What is the BEST way to reduce privileges?
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
✓
Delete the ClusterRoleBinding that grants cluster-admin to the service account
Option B is correct because the service account 'my-sa' has cluster-admin privileges due to a ClusterRoleBinding that binds it to the 'cluster-admin' ClusterRole. Deleting that specific ClusterRoleBinding removes the excessive permissions without affecting other subjects or the underlying ClusterRole, which is shared and may be needed by other users or components. This is the most targeted and least disruptive approach to reduce privileges.
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.
✗
Delete the service account and create a new one
Why it's wrong here
This does not address the underlying binding; the new service account might still get cluster-admin if the binding is recreated.
✓
Delete the ClusterRoleBinding that grants cluster-admin to the service account
Why this is correct
Removing the binding eliminates the excessive privileges.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Create a new RoleBinding with fewer privileges in the kube-system namespace
Why it's wrong here
This does not remove the existing cluster-admin binding.
✗
Modify the ClusterRole 'cluster-admin' to have fewer permissions
Why it's wrong here
Modifying the built-in cluster-admin role affects all subjects bound to it.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CNCF often tests the misconception that modifying a ClusterRole or recreating a service account is sufficient to revoke privileges, when in reality the binding is the source of the permission grant and must be removed directly.
Detailed technical explanation
How to think about this question
In Kubernetes, RBAC bindings are additive and independent; a subject can have multiple RoleBindings and ClusterRoleBindings, and the effective permissions are the union of all bound roles. Deleting the ClusterRoleBinding is the only way to remove the cluster-admin grant without impacting other bindings or the ClusterRole itself. The 'cluster-admin' ClusterRole is a built-in role that aggregates permissions via the 'system:master' group and is often used by system components like controllers, so modifying it could cause widespread failures.
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: Delete the ClusterRoleBinding that grants cluster-admin to the service account — Option B is correct because the service account 'my-sa' has cluster-admin privileges due to a ClusterRoleBinding that binds it to the 'cluster-admin' ClusterRole. Deleting that specific ClusterRoleBinding removes the excessive permissions without affecting other subjects or the underlying ClusterRole, which is shared and may be needed by other users or components. This is the most targeted and least disruptive approach to reduce privileges.
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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