Question 722 of 1,711
DEA-C01 Data Store Management Practice Question
Which TWO actions should a data engineer take to encrypt data at rest in an Amazon S3 bucket? (Select TWO.)
⚠ Common exam trap
Many exam-takers 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.
Answer choices
Why each option matters
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.
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.
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.
- ✓
Enable default encryption on the bucket using SSE-S3.
Why this is correct
SSE-S3 encrypts objects at rest with S3-managed keys.
- ✗
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.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
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Last reviewed: Jun 11, 2026
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.
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