DBS-C01 AWS-owned CMK Practice Question
Which THREE are valid methods to encrypt data at rest in Amazon DynamoDB? (Choose 3.)
⚠ Common exam trap
The trap is that candidates often assume client-side encryption counts as 'encryption at rest' for DynamoDB, but encryption at rest refers to server-side encryption by the service itself. Additionally, some may think customer managed CMKs are not supported, but they are.
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 a customer managed CMK.
DynamoDB encryption at rest is implemented through AWS KMS, supporting three types of customer master keys (CMKs): AWS-owned CMKs (default), AWS managed CMKs, and customer managed CMKs. Option A is correct because customer managed CMKs are fully supported, allowing you to create, manage, and control key policies and rotation. Option C (AWS-owned) and D (AWS managed) are also correct. Option E (client-side encryption with DynamoDB Encryption Client) is not an encryption-at-rest method provided by DynamoDB; it encrypts data before transmission, but data at rest is still encrypted by DynamoDB's server-side encryption. Option B is irrelevant as S3 server-side encryption does not apply to DynamoDB.
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 a customer managed CMK.
Why this is correct
Correct. Customer managed CMKs are fully supported for DynamoDB encryption at rest, providing control over key policies and rotation.
- ✗
Use S3 server-side encryption.
Why it's wrong here
Incorrect. S3 server-side encryption is specific to Amazon S3 and does not apply to DynamoDB.
- ✓
Use an AWS-owned CMK.
Why this is correct
Correct. AWS-owned CMKs are the default encryption keys used by DynamoDB.
- ✓
Use an AWS managed CMK.
Why this is correct
Correct. AWS managed CMKs are another valid option, created and managed in KMS.
- ✗
Use client-side encryption with the DynamoDB Encryption Client.
Why it's wrong here
Incorrect. Client-side encryption with the DynamoDB Encryption Client encrypts data before it reaches DynamoDB, but it is not a method provided by DynamoDB for encryption at rest; encryption at rest is handled server-side by DynamoDB.
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 DBS-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 DBS-C01 exam.