DEA-C01 Data Store Management Practice Question
A company uses Amazon S3 to store sensitive documents. The security team has mandated that all objects must be encrypted at rest using server-side encryption with AWS KMS (SSE-KMS). Additionally, the company wants to ensure that any attempt to upload an unencrypted object is denied. A data engineer has configured a bucket policy that denies PutObject if the encryption header does not include x-amz-server-side-encryption: aws:kms. However, the engineer notices that some objects are still being stored without encryption. Upon investigation, the engineer suspects that the policy is not being evaluated correctly. What should the engineer do to ensure that all objects are encrypted with SSE-KMS?
⚠ Common exam trap
Many candidates assume a bucket policy condition denying PutObject without `x-amz-server-side-encryption: aws:kms` will block all unencrypted uploads, but they overlook that the condition only matches when the header is present with a wrong value, not when the header is absent entirely.
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 with SSE-KMS.
Enabling default encryption on the S3 bucket with SSE-KMS ensures that any object uploaded without an explicit encryption header is automatically encrypted with SSE-KMS. This closes the gap where the bucket policy condition fails to catch uploads that omit the `x-amz-server-side-encryption` header entirely, as the policy only denies requests with an incorrect header but does not block requests that lack the header altogether. Default encryption applies server-side encryption at the bucket level, making it impossible to store an unencrypted object.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use an IAM policy to require encryption instead of a bucket policy.
Why it's wrong here
IAM policies can require encryption, but bucket policies are more direct.
- ✗
Enable S3 Block Public Access settings.
Why it's wrong here
Block Public Access does not enforce encryption.
- ✗
Add a condition to the bucket policy that checks for aws:SourceVpce.
Why it's wrong here
This condition is for VPC endpoint, not encryption.
- ✓
Enable default encryption on the S3 bucket with SSE-KMS.
Why this is correct
Default encryption ensures all objects are encrypted, complementing the bucket policy.
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.