This CKS practice question tests your understanding of system hardening. 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.
Which TWO of the following are effective measures to harden the Kubernetes API server against unauthorized access?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable the NodeRestriction admission controller
The NodeRestriction admission controller limits the Node and Pod objects a kubelet can modify, preventing compromised nodes from accessing or modifying resources beyond their own. This is a key hardening measure because it enforces the principle of least privilege directly within the API server's admission chain, reducing the blast radius of a node compromise.
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.
✓
Enable the NodeRestriction admission controller
Why this is correct
Limits what nodes can modify, reducing attack surface.
Related concept
Read the scenario before looking for a memorised answer.
✗
Set --anonymous-auth=true to allow all users
Why it's wrong here
This would allow unauthorized access.
✗
Enable audit logging to detect unauthorized attempts
Why it's wrong here
Audit logs only detect, not prevent.
✗
Disable all authentication mechanisms and rely on network policies
Why it's wrong here
Disabling auth is insecure.
✓
Configure the API server to use TLS certificates for client authentication
Why this is correct
Mutual TLS ensures only clients with valid certs can connect.
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 preventive controls (like admission controllers and authentication) and detective controls (like audit logging), so candidates mistakenly select audit logging as a hardening measure when it only detects, not prevents, unauthorized access.
Detailed technical explanation
How to think about this question
The NodeRestriction admission controller works by examining the 'node' and 'node.status' subresources, ensuring a kubelet can only modify its own Node object and Pods bound to that node. Under the hood, it validates the request's username (derived from the TLS client certificate) against the node name, rejecting any cross-node access. In a real-world scenario, if an attacker compromises a worker node, this controller prevents the kubelet from reading secrets or modifying pods on other nodes, containing the breach.
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.
System Hardening — This question tests System Hardening — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable the NodeRestriction admission controller — The NodeRestriction admission controller limits the Node and Pod objects a kubelet can modify, preventing compromised nodes from accessing or modifying resources beyond their own. This is a key hardening measure because it enforces the principle of least privilege directly within the API server's admission chain, reducing the blast radius of a node compromise.
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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