The answer is to apply a bucket policy that denies PutObject requests without the x-amz-server-side-encryption header and to enable default encryption on the bucket using SSE-S3 or SSE-KMS. These two actions work together to enforce S3 data encryption at rest: the bucket policy acts as a gatekeeper, rejecting any upload that lacks the required encryption header, while default encryption acts as a safety net, automatically encrypting objects even if the upload request omits the header. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of defense-in-depth for S3 security, often appearing as a scenario where you must prevent unencrypted writes. A common trap is assuming default encryption alone is sufficient, but without the bucket policy, a malicious actor could still bypass encryption headers by relying on the default—only the policy enforces the requirement at the API level. Memory tip: think “Policy first, default second” to lock down every write.
DEA-C01 Data Store Management Practice Question
This DEA-C01 practice question tests your understanding of data store management. 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 TWO actions are recommended for securing data at rest in Amazon S3? (Choose two.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable default encryption on the S3 bucket using SSE-S3 or SSE-KMS.
Option A is correct because enabling default encryption on an S3 bucket using SSE-S3 or SSE-KMS ensures that all objects stored in the bucket are encrypted at rest automatically, even if the upload request does not include encryption headers. This satisfies the requirement for securing data at rest by applying server-side encryption to every object written to the bucket.
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 default encryption on the S3 bucket using SSE-S3 or SSE-KMS.
Why this is correct
Ensures all new objects are encrypted automatically.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use S3 Bucket Key to reduce KMS request costs.
Why it's wrong here
Cost optimization, not a security requirement.
✗
Enable S3 Versioning to protect against accidental deletions.
Why it's wrong here
Versioning is for data protection, not encryption.
✓
Apply a bucket policy that denies PutObject requests without the x-amz-server-side-encryption header.
Why this is correct
Enforces encryption for all uploads.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure cross-region replication to replicate data to another bucket.
Why it's wrong here
Replication is for durability, not encryption enforcement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse data protection features like Versioning or replication with encryption controls, but the question specifically asks for securing data at rest, which requires encryption mechanisms such as default encryption or policy-enforced encryption headers.
Detailed technical explanation
How to think about this question
Server-side encryption with SSE-S3 uses AES-256 encryption managed by Amazon S3, while SSE-KMS uses AWS KMS-managed keys, providing additional control over key rotation and audit trails via AWS CloudTrail. The bucket policy in Option D enforces encryption by denying any PutObject request that lacks the x-amz-server-side-encryption header, ensuring that only encrypted objects are written, which complements default encryption for a defense-in-depth approach.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Data Store Management — This question tests Data Store Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable default encryption on the S3 bucket using SSE-S3 or SSE-KMS. — Option A is correct because enabling default encryption on an S3 bucket using SSE-S3 or SSE-KMS ensures that all objects stored in the bucket are encrypted at rest automatically, even if the upload request does not include encryption headers. This satisfies the requirement for securing data at rest by applying server-side encryption to every object written to the bucket.
What should I do if I get this DEA-C01 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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This DEA-C01 practice question is part of Courseiva's free Amazon Web Services 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 DEA-C01 exam.
Question Discussion
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