DEA-C01 Data Store Management Practice Question
Which TWO actions are recommended for securing data at rest in Amazon S3? (Choose two.)
⚠ Common exam trap
A common mix-up: candidates 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.
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
✓
Enable default encryption on the S3 bucket using SSE-S3 or SSE-KMS.
Option A is correct because enabling default bucket encryption with SSE-S3 or SSE-KMS ensures that every object written to the bucket is automatically encrypted at rest, satisfying the core requirement for data-at-rest protection in Amazon S3. Option D is correct because a bucket policy that denies PutObject requests lacking the x-amz-server-side-encryption header enforces encryption on upload, preventing unencrypted objects from being stored even if default encryption is bypassed or misconfigured. Option B is not a security control; S3 Bucket Key reduces AWS KMS request costs and CloudTrail event volume but does not itself secure data at rest. Option C addresses availability and data durability against accidental deletion through versioning, not encryption at rest. Option E provides geographic redundancy and disaster recovery via cross-region replication, but replication does not encrypt data at rest by itself.
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
Enabling default encryption ensures every object written to the bucket is encrypted at rest automatically, satisfying the data-at-rest requirement without relying on per-request headers. SSE-S3 provides AES-256 with Amazon-managed keys, while SSE-KMS adds customer-managed key control and audit trails through CloudTrail, meeting compliance needs.
- ✗
Use S3 Bucket Key to reduce KMS request costs.
Why it's wrong here
S3 Bucket Key cuts KMS request costs and throttling by generating a short-lived bucket-level data key; it changes no encryption state, so it does not itself secure data at rest. It is tempting because it is configured alongside SSE-KMS, and would be correct when the requirement is reducing KMS API calls or cost.
- ✗
Enable S3 Versioning to protect against accidental deletions.
Why it's wrong here
Versioning preserves prior object versions against overwrite or deletion; it does not encrypt data at rest, so it fails the stated securing-at-rest requirement. It is tempting because versioning genuinely protects against accidental deletion and ransomware tampering, and would be the right control for a durability or recoverability question rather than encryption.
- ✓
Apply a bucket policy that denies PutObject requests without the x-amz-server-side-encryption header.
Why this is correct
Enforcing the x-amz-server-side-encryption header via a bucket policy denies any PutObject lacking encryption instructions, guaranteeing every uploaded object is encrypted at rest. This satisfies the stem's data-at-rest protection requirement by preventing unencrypted writes rather than merely detecting them.
- ✗
Configure cross-region replication to replicate data to another bucket.
Why it's wrong here
Cross-region replication copies objects to another bucket, providing durability and availability, but the replicated data remains unencrypted unless encryption is separately applied. It is tempting because replication is a recommended S3 resilience control, and it would be correct for a question about disaster recovery or geographic redundancy.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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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.