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 valid arguments for etcd encryption at rest?
kms
Why wrong: kms is a valid provider but not specifically for etcd encryption; it's for Kubernetes secret encryption.
identity
Why wrong: identity means no encryption.
base64
Why wrong: base64 is not a provider for encryption.
secretbox
Correct. secretbox is a supported provider.
aescbc
Correct. aescbc is a supported provider.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
secretbox
Option D (secretbox) is correct because it is a valid encryption provider for etcd data at rest in Kubernetes, using XSalsa20 and Poly1305 for authenticated encryption. It is one of the supported providers alongside aescbc, and is specifically designed for encryption at rest within etcd.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
kms
Why it's wrong here
kms is a valid provider but not specifically for etcd encryption; it's for Kubernetes secret encryption.
identity
Why it's wrong here
identity means no encryption.
base64
Why it's wrong here
base64 is not a provider for encryption.
secretbox
Why this is correct
Correct. secretbox is a supported provider.
Related concept
Read the scenario before looking for a memorised answer.
aescbc
Why this is correct
Correct. aescbc is a supported provider.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
CNCF often tests the distinction between encryption providers and encoding/identity, where candidates mistakenly think 'base64' or 'identity' provide encryption, or confuse KMS (a key management integration) with an etcd encryption provider.
Detailed technical explanation
Etcd encryption at rest is configured via the '--encryption-provider-config' flag on the kube-apiserver, which accepts a YAML file listing providers like 'aescbc' and 'secretbox'. 'secretbox' uses NaCl/libsodium's SecretBox construction (XSalsa20-Poly1305) for authenticated encryption, while 'aescbc' uses AES-CBC with PKCS#7 padding; both require a 32-byte key. In production, secretbox is often preferred for its simpler implementation and resistance to padding oracle attacks compared to aescbc.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the CKS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
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FAQ
Cluster Setup and Hardening — This question tests Cluster Setup and Hardening — Read the scenario before looking for a memorised answer..
The correct answer is: secretbox — Option D (secretbox) is correct because it is a valid encryption provider for etcd data at rest in Kubernetes, using XSalsa20 and Poly1305 for authenticated encryption. It is one of the supported providers alongside aescbc, and is specifically designed for encryption at rest within etcd.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CKS practice question is part of Courseiva's free CNCF certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CKS exam.
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