DEA-C01 Data Security and Governance Practice Question
A company uses Amazon S3 to store sensitive customer data. The security policy requires that all objects in the bucket be encrypted at rest using server-side encryption with a customer-managed KMS key. The data engineer has enabled default encryption on the bucket using SSE-KMS with the required KMS key. However, a security scan reveals that some objects in the bucket are not encrypted with the KMS key. The objects were uploaded before the default encryption was enabled. The data engineer needs to ensure that all objects are encrypted with the KMS key without disrupting ongoing data access. What should the data engineer do?
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
✓
Use S3 Batch Operations with a Lambda function to apply SSE-KMS encryption to all existing objects using the KMS key.
S3 Batch Operations can apply SSE-KMS encryption to existing objects without disrupting access. It uses a Lambda function to re-encrypt each object with the specified KMS key. Option A is wrong because copying objects to themselves with the --sse-kms-key-id parameter does not work - it requires a full copy to a new location and back. Option B is wrong because the bucket policy only prevents new unencrypted uploads, it does not fix existing objects. Option C is wrong because deleting and re-uploading disrupts access and is inefficient.
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 the AWS CLI to copy the objects to themselves with the --sse-kms-key-id parameter.
Why it's wrong here
Copying objects to themselves with the AWS CLI and --sse-kms-key-id parameter does not re-encrypt in place; it would require a full copy to a new location and back, which is inefficient.
- ✗
Modify the bucket policy to deny access to objects not encrypted with the KMS key.
Why it's wrong here
Modifying the bucket policy to deny access to unencrypted objects only prevents access to those objects, but does not encrypt them; it would also disrupt ongoing access.
- ✗
Delete the unencrypted objects and re-upload them with encryption.
Why it's wrong here
Deleting and re-uploading objects is disruptive and inefficient; it can cause data loss and access interruptions.
- ✓
Use S3 Batch Operations with a Lambda function to apply SSE-KMS encryption to all existing objects using the KMS key.
Why this is correct
S3 Batch Operations with a Lambda function can re-encrypt all existing objects using SSE-KMS with the required KMS key, without disrupting data access.
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.