DEA-C01 Data Security and Governance Practice Question
A data engineer needs to share a dataset from an S3 bucket in Account A with users in Account B. The dataset must remain encrypted at rest with an S3-managed key. What is the MOST secure way to grant cross-account access?
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
✓
Create a bucket policy that grants cross-account access to an IAM role in Account B.
A bucket policy granting access to the IAM role in Account B is the recommended secure method for cross-account access to S3 objects encrypted with S3-managed keys. Option A is insecure because it grants public access. Option C is incorrect because ACLs are legacy and less secure for cross-account scenarios. Option D is incorrect because while S3 VPC endpoints are a valid AWS feature that provides private connectivity to S3, they do not grant cross-account access; bucket policies are still required to authorize access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Make the bucket public and use bucket policies to allow only Account B users.
Why it's wrong here
Making the bucket public grants public access, which is insecure and not recommended.
- ✓
Create a bucket policy that grants cross-account access to an IAM role in Account B.
Why this is correct
A bucket policy granting cross-account access to an IAM role in Account B is the recommended secure method.
- ✗
Use S3 object ACLs to grant access to Account B's root user.
Why it's wrong here
S3 object ACLs are legacy and less secure; bucket policies are preferred.
- ✗
Use an S3 VPC endpoint to allow Account B users through private IPs.
Why it's wrong here
While S3 VPC endpoints are a valid AWS feature for private connectivity, they do not grant cross-account access. Access must still be authorized via IAM policies or bucket policies.
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.