How to Enable Encryption at Rest on Amazon RDS for MySQL
A company is deploying a new Amazon RDS for MySQL database. The security team requires that all data at rest be encrypted. What is the simplest way to meet this requirement?
Quick Answer
The answer is to enable encryption at rest when creating the RDS instance using an AWS KMS key. This is correct because Amazon RDS for MySQL integrates with AWS Key Management Service to transparently encrypt the underlying storage, automated backups, read replicas, and snapshots, but crucially, encryption must be enabled at instance creation time—it cannot be added to an existing unencrypted instance. On the AWS Certified Database Specialty DBS-C01 exam, this concept tests your understanding of RDS encryption limitations and the principle that security configurations like encryption at rest are immutable post-launch. A common trap is assuming you can later modify an unencrypted DB instance to add encryption, which is not supported; instead, you must migrate data to a new encrypted instance. Remember the mnemonic: “Create to Encrypt, or you’ll decrypt your options.”
⚠ Common exam trap
A common mix-up: candidates think encryption can be enabled after creation (Option D) because some AWS services allow post-creation encryption, but RDS requires encryption to be set at launch, and this is a common exam trick to test knowledge of RDS encryption limitations.
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 encryption at rest when creating the RDS instance using an AWS KMS key
Amazon RDS for MySQL supports encryption at rest using AWS KMS keys, which must be enabled at instance creation time because encryption cannot be added to an existing unencrypted RDS instance. Option C is correct because it describes the simplest and most direct method: enabling encryption at rest during the initial RDS instance creation with an AWS KMS key, which transparently encrypts the underlying storage, automated backups, read replicas, and snapshots.
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 encryption using AWS Certificate Manager
Why it's wrong here
ACM is for SSL/TLS certificates, not encryption at rest.
- ✗
Use client-side encryption in the application
Why it's wrong here
Client-side encryption shifts the encryption responsibility to the application layer, but the security requirement mandates that *all data at rest* be encrypted within the database service itself — RDS for MySQL does not natively enforce or manage application-level encryption keys, so this approach fails to guarantee that the storage layer (e.g., EBS volumes and automated backups) is encrypted. It is tempting because client-side encryption provides end-to-end confidentiality for data in transit and at rest in the application’s control, and would be the correct choice if the requirement were to prevent the database provider (or anyone with access to the RDS instance) from reading the plaintext data.
- ✓
Enable encryption at rest when creating the RDS instance using an AWS KMS key
Why this is correct
Encryption at rest can be enabled at instance creation time using a KMS key.
- ✗
Enable encryption at rest on the RDS instance after creation
Why it's wrong here
Encryption cannot be enabled on an existing RDS instance; it must be done at creation.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
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| 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 |
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| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
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Same concept, more angles
1 more way this is tested on DBS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is deploying a MySQL database on Amazon RDS and needs to enforce encryption at rest. Which configuration step is required?
medium- A.Use a custom DB parameter group with SSL enabled.
- B.Modify the DB instance to enable encryption after creation.
- C.Enable SSL/TLS on the RDS instance.
- ✓ D.Select encryption option when creating the RDS instance.
Why D: Amazon RDS for MySQL requires encryption at rest to be enabled at instance creation time by selecting the encryption option in the AWS Management Console, CLI, or API. Encryption at rest uses AWS Key Management Service (KMS) to encrypt the underlying storage, automated backups, read replicas, and snapshots. This setting cannot be applied to an existing unencrypted DB instance, so it must be chosen during the initial launch.
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.