DEA-C01 Data Store Management Practice Question

A financial services company stores sensitive transaction data in an Amazon S3 bucket. The security team requires that all data be encrypted at rest using AWS Key Management Service (AWS KMS) customer managed keys, and that the encryption keys be automatically rotated every year. A data engineer needs to configure the S3 bucket to meet these requirements with minimal ongoing operational effort. Which solution should the engineer implement?

⚠ Common exam trap

The trap here is assuming that SSE-S3 or AWS managed keys provide customer control over rotation, when only customer managed keys allow configuring annual automatic rotation.

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 using SSE-KMS with a customer managed key that has automatic key rotation enabled.

To meet the requirements, the engineer should use server-side encryption with AWS KMS customer managed keys (SSE-KMS) and enable automatic key rotation on the key. This ensures data is encrypted at rest with a key the customer controls, and rotation occurs annually without manual intervention. The bucket default encryption setting ensures all new objects are encrypted automatically.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Enable default encryption on the S3 bucket using SSE-S3 (AES-256).
Why it's wrong here
SSE-S3 uses Amazon S3 managed keys, not AWS KMS customer managed keys. It does not provide the ability to control key rotation policies or audit key usage through AWS KMS. This fails the requirement for customer managed keys and automatic annual rotation.
✓
Enable default encryption on the S3 bucket using SSE-KMS with a customer managed key that has automatic key rotation enabled.
Why this is correct
SSE-KMS with a customer managed key allows the use of AWS KMS keys that the customer controls. Enabling automatic key rotation on the customer managed key rotates the key material every year by default, meeting the annual rotation requirement. This configuration requires minimal ongoing effort because S3 automatically encrypts new objects with the specified key.
✗
Use S3 client-side encryption with a customer-provided key stored in AWS Secrets Manager, and rotate the key annually using a Lambda function.
Why it's wrong here
Client-side encryption requires the application to encrypt data before uploading, adding complexity. Managing key rotation with a custom Lambda function introduces operational overhead and potential errors. This approach does not leverage AWS KMS customer managed keys and does not provide the same level of integration and auditability.
✗
Enable default encryption on the S3 bucket using SSE-KMS with an AWS managed key (aws/s3).
Why it's wrong here
SSE-KMS with an AWS managed key uses a key owned by AWS, not a customer managed key. The rotation of AWS managed keys is handled by AWS every three years, not annually, and customers cannot configure rotation. This does not meet the requirement for customer managed keys with annual rotation.

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

DEA-C01 Data Store Management Practice Question

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

Related to this question