DEA-C01 Data Security and Governance Practice Question
A company stores sensitive data in an Amazon S3 bucket. To comply with regulations, all data must be encrypted at rest using server-side encryption. The security team wants to ensure that any attempt to upload an unencrypted object is automatically denied. Which S3 bucket policy condition should be used?
⚠ Common exam trap
DEA-C01 often tests the confusion between default bucket encryption (which silently encrypts) and a bucket policy condition that explicitly denies unencrypted PUTs — candidates pick the KMS key ID condition thinking it enforces encryption, but only the base x-amz-server-side-encryption key does.
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
✓
s3:x-amz-server-side-encryption
The bucket policy condition key s3:x-amz-server-side-encryption matches the x-amz-server-side-encryption request header that S3 requires on PUT requests when server-side encryption is specified. By using a Deny effect with a StringNotEquals condition on this key (or Null check), any PutObject request that does not include the encryption header is rejected before the object is written. This enforces encryption at rest at the API layer, regardless of client behavior.
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:x-amz-server-side-encryption-aws-kms-key-id
Why it's wrong here
This enforces a specific KMS key, but the requirement is simply to encrypt, not to use a particular key.
- ✗
s3:x-amz-acl
Why it's wrong here
s3:x-amz-acl evaluates the canned ACL header, which governs object permissions, not encryption, so unencrypted uploads would still succeed. It is tempting because it is a genuine S3 request condition, but the correct condition must inspect the encryption header itself, such as s3:x-amz-server-side-encryption.
- ✓
s3:x-amz-server-side-encryption
Why this is correct
The `s3:x-amz-server-side-encryption` condition key inspects the `x-amz-server-side-encryption` request header, letting the bucket policy deny any PutObject lacking a server-side encryption algorithm. This directly enforces the stem's requirement that unencrypted uploads be automatically rejected, since requests without that header fail the condition.
- ✗
s3:x-amz-storage-class
Why it's wrong here
s3:x-amz-storage-class validates the requested storage class header, not whether encryption is present, so unencrypted uploads still pass. It is tempting because it does restrict PUTs, but only to enforce a class such as STANDARD_IA; the encryption condition must instead inspect s3:x-amz-server-side-encryption.
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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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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.