This CKS practice question tests your understanding of cluster setup and 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 recommended practices for etcd security?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Restrict etcd access to only the API server and kubelets using firewall rules
Option C is correct because etcd stores sensitive cluster data (secrets, config maps, state). Restricting network access to only the API server and kubelets via firewall rules (e.g., iptables or cloud security groups) minimizes the attack surface and prevents unauthorized nodes or external actors from reaching the etcd data store. This aligns with the principle of least privilege for control plane components.
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.
Restrict etcd access to only the API server and kubelets using firewall rules
Why this is correct
Network restrictions limit which hosts can connect to etcd.
Related concept
Read the scenario before looking for a memorised answer.
✗
Expose etcd on a public IP for monitoring
Why it's wrong here
etcd should not be exposed publicly.
✓
Enable TLS client certificate authentication
Why this is correct
Mutual TLS ensures only authenticated clients can access etcd.
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 disabling TLS or exposing etcd is acceptable for monitoring or performance, when in reality etcd must always be isolated and encrypted to protect the cluster's root of trust.
Detailed technical explanation
How to think about this question
etcd uses the gRPC protocol with mutual TLS (mTLS) for client-server and peer-to-peer communication. The API server authenticates to etcd using a client certificate signed by the etcd CA, and etcd verifies the API server's certificate against its trusted CA bundle. In a real-world scenario, a misconfigured security group allowing inbound traffic on port 2379 from 0.0.0.0/0 could lead to a cluster compromise if an attacker discovers the endpoint, even without valid credentials.
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: Restrict etcd access to only the API server and kubelets using firewall rules — Option C is correct because etcd stores sensitive cluster data (secrets, config maps, state). Restricting network access to only the API server and kubelets via firewall rules (e.g., iptables or cloud security groups) minimizes the attack surface and prevents unauthorized nodes or external actors from reaching the etcd data store. This aligns with the principle of least privilege for control plane components.
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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