DEA-C01 Data Security and Governance Practice Question
A company uses S3 to store sensitive data. Which TWO S3 features can be used to protect data at rest?
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
✓
Server-Side Encryption with S3 Managed Keys (SSE-S3)
SSE-S3 (option B) is correct because it encrypts objects at rest using AES-256 with keys fully managed by Amazon S3, directly protecting stored data without any customer key management. SSE-KMS (option C) is also correct because it encrypts objects at rest using AWS KMS customer master keys, adding key control, audit trails via CloudTrail, and separation of duties. S3 Versioning (A) only keeps multiple variants of an object to aid recovery; it does not encrypt data. S3 Transfer Acceleration (D) speeds up uploads/downloads over AWS edge locations and is a transfer optimization, not encryption at rest. S3 Object Lock (E) enforces WORM retention to prevent deletion or modification, which is immutability, not encryption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
S3 Versioning
Why it's wrong here
S3 Versioning preserves prior object states against overwrite or deletion but applies no encryption, so it does not protect data at rest. It is tempting because it is a genuine data-protection feature, and would be correct for recovering from accidental deletion or maintaining an audit trail of object changes.
- ✓
Server-Side Encryption with S3 Managed Keys (SSE-S3)
Why this is correct
SSE-S3 encrypts objects at rest using AES-256, with Amazon S3 managing the key material and rotation automatically. This satisfies the stem's data-at-rest protection requirement without the company provisioning or maintaining keys in AWS KMS, removing key-management overhead entirely.
- ✓
Server-Side Encryption with AWS KMS (SSE-KMS)
Why this is correct
SSE-KMS encrypts objects at rest using keys managed in AWS KMS, directly satisfying the data-at-rest protection requirement. It adds envelope encryption with separate data keys plus audit trails via CloudTrail, and supports customer-managed keys for granular access control and key rotation policies.
- ✗
S3 Transfer Acceleration
Why it's wrong here
S3 Transfer Acceleration speeds uploads and downloads over long distances using edge locations; it affects data in transit and provides no encryption at rest. It is tempting because it is a performance and security-adjacent feature, and would be correct for accelerating transfers to a bucket from geographically distant clients.
- ✗
S3 Object Lock
Why it's wrong here
S3 Object Lock prevents deletion or modification for a retention period, guarding integrity and availability rather than confidentiality, so it does not encrypt data at rest. It is tempting because it is a strong protection control, and would be correct for meeting WORM compliance obligations such as SEC 17a-4.
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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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.