The correct answer is to enable default encryption on the bucket using SSE-S3 and to use SSE-KMS with AWS KMS. These two actions encrypt data at rest in S3 by ensuring every object is automatically encrypted before being written to disk, either with S3’s own AES-256 key (SSE-S3) or with a customer-managed KMS key that provides envelope encryption—where a data key encrypts the object and the CMK encrypts that data key. On the AWS Certified Data Engineer Associate DEA-C01 exam, this question tests your understanding of server-side encryption options and the distinction between S3-managed keys and KMS-managed keys. A common trap is confusing SSE-S3 with client-side encryption or assuming bucket policies alone enforce encryption; remember that default encryption applies automatically to all uploads lacking explicit headers. For a quick memory tip, think “S3-Simple, KMS-Keyed”—SSE-S3 is the simplest automatic option, while SSE-KMS gives you audit control and key rotation.
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 should a data engineer take to encrypt data at rest in an Amazon S3 bucket? (Select TWO.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Configure the bucket to use SSE-KMS.
Option C is correct because SSE-KMS (Server-Side Encryption with AWS Key Management Service) encrypts data at rest in S3 by using a KMS key to manage encryption keys. This provides envelope encryption, where a CMK generates a data key that encrypts the object, and the data key is then encrypted by the CMK. Option D is correct because enabling default encryption on an S3 bucket using SSE-S3 (AES-256) ensures that all objects uploaded without explicit encryption headers are automatically encrypted at rest by S3's managed key.
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 S3 Transfer Acceleration on the bucket.
Why it's wrong here
Transfer Acceleration speeds up transfers, does not encrypt.
✗
Use client-side encryption before uploading objects to S3.
Why it's wrong here
Client-side encryption encrypts before upload, but the question asks for data at rest which can be achieved server-side.
✓
Configure the bucket to use SSE-KMS.
Why this is correct
SSE-KMS encrypts objects at rest using AWS KMS keys.
Related concept
Read the scenario before looking for a memorised answer.
✓
Enable default encryption on the bucket using SSE-S3.
Why this is correct
SSE-S3 encrypts objects at rest with S3-managed keys.
Related concept
Read the scenario before looking for a memorised answer.
✗
Attach a bucket policy that denies unencrypted PUT requests.
Why it's wrong here
Bucket policies enforce whether objects must be encrypted at upload, but do not automatically encrypt data at rest.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse enforcing encryption (via bucket policies) with actually performing encryption, or they mistakenly think client-side encryption is a bucket-level action rather than a client-side responsibility.
Detailed technical explanation
How to think about this question
SSE-KMS uses envelope encryption: the KMS CMK generates a plaintext data key and an encrypted copy; S3 encrypts the object with the plaintext key, then discards it, storing only the encrypted key alongside the object. This allows key rotation and audit trails via AWS CloudTrail. SSE-S3 uses S3-managed keys with AES-256-GCM, providing a simpler, fully managed option with no additional cost, but lacks granular control over key rotation or access logging.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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: Configure the bucket to use SSE-KMS. — Option C is correct because SSE-KMS (Server-Side Encryption with AWS Key Management Service) encrypts data at rest in S3 by using a KMS key to manage encryption keys. This provides envelope encryption, where a CMK generates a data key that encrypts the object, and the data key is then encrypted by the CMK. Option D is correct because enabling default encryption on an S3 bucket using SSE-S3 (AES-256) ensures that all objects uploaded without explicit encryption headers are automatically encrypted at rest by S3's managed key.
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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Question Discussion
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