DEA-C01 Data Security and Governance Practice Question
A data engineer needs to share a dataset from an S3 bucket in Account A with another AWS account (Account B). The data must remain encrypted at rest with KMS. Which steps are required?
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
✓
Update the S3 bucket policy and the KMS key policy to allow Account B
The correct steps are to update both the S3 bucket policy to grant Account B access to the objects and the KMS key policy to grant Account B the necessary decrypt permissions. Option A is insufficient because it only updates the KMS key policy; the bucket policy must also be updated to allow Account B's access to the S3 objects. Option B is also insufficient because creating an IAM role alone does not grant KMS decrypt permissions; the KMS key policy must be updated. Option C is correct as it includes both. Option D is insufficient because it only updates the bucket policy, not the KMS key policy.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Update the KMS key policy to allow Account B's root user
Why it's wrong here
Updating only the KMS key policy does not grant access to the S3 bucket; bucket policy is also required.
- ✗
Create an IAM role in Account A and grant cross-account access
Why it's wrong here
Creating an IAM role with cross-account access is a valid method, but the question's correct answer requires both bucket policy and key policy updates.
- ✓
Update the S3 bucket policy and the KMS key policy to allow Account B
Why this is correct
Correct: Both the S3 bucket policy and the KMS key policy must be updated to allow Account B.
- ✗
Update the S3 bucket policy to allow Account B's root user
Why it's wrong here
Updating only the S3 bucket policy does not grant permission to decrypt the KMS key.
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.