SCS-C02 Data Protection Practice Question
Which TWO of the following are valid options for encrypting data at rest in Amazon EBS? (Choose two.)
⚠ Common exam trap
SCS-C02 often tests the difference between native AWS encryption mechanisms and application-level or unrelated service encryption; candidates may pick CloudHSM or S3 encryption thinking they apply to EBS, but only KMS-based options are valid for EBS at rest.
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 EBS encryption by default using the AWS managed key for EBS.
Option A is correct because Amazon EBS supports account-level and Region-level encryption by default, which automatically encrypts new volumes and snapshots using the AWS managed key for EBS (aws/ebs) unless you specify a different key. Option B is correct because EBS encryption can be configured to use a customer managed KMS key, giving you control over key policies, rotation, and grants while still using the native EBS/KMS encryption mechanism. Option C is not a valid EBS at-rest encryption option because running an encryption script inside the EC2 instance is application-level or OS-level encryption, not native EBS volume encryption. Option D is not correct because CloudHSM is a separate HSM service and is not the mechanism used to generate or store EBS encryption keys; EBS encryption keys are managed through AWS KMS. Option E is not correct because S3 server-side encryption protects objects stored in S3, not EBS volumes or EBS 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 EBS encryption by default using the AWS managed key for EBS.
Why this is correct
Enabling EBS encryption by default causes all newly created EBS volumes and snapshots to be encrypted automatically. When no custom key is specified, AWS uses the AWS managed key with alias 'aws/ebs' to perform encryption, which is transparent and requires no additional configuration. This satisfies encryption-at-rest requirements with minimal operational overhead and is the simplest valid option.
- ✓
Use a customer managed KMS key.
Why this is correct
Selecting a customer managed KMS key gives you full control over the key lifecycle, including rotation, permissions, and audit logs. When you enable EBS encryption by default, you can optionally specify a customer managed key instead of the default AWS managed key, or you can choose one during volume or snapshot creation. This is useful for meeting compliance policies that require separation of duties or cross-account key sharing, and it remains a fully supported, native EBS encryption method.
- ✗
Use an encryption script on the EC2 instance to encrypt the volume.
Why it's wrong here
Running an encryption script inside the EC2 instance, such as using LUKS or dm-crypt, performs encryption in the guest OS before data reaches the EBS volume, which is application- or OS-level encryption, not AWS-native EBS encryption. EBS encryption is applied by the EBS service using KMS keys at the storage layer, independent of the instance. Moreover, snapshots taken from such a volume would not be automatically encrypted by EBS encryption, so you would still need to separately manage native snapshot encryption to meet at-rest encryption requirements.
- ✗
Use AWS CloudHSM to generate and store the encryption key.
Why it's wrong here
AWS CloudHSM provides dedicated hardware security modules for cryptographic operations, but EBS volume encryption does not integrate with CloudHSM directly; it uses AWS KMS keys (either AWS managed or customer managed). While you can configure a custom key store in KMS backed by CloudHSM, that is an advanced configuration and not a direct option for simply encrypting EBS volumes. Choosing CloudHSM as a standalone service without KMS integration would not encrypt EBS volumes or snapshots.
- ✗
Use S3 server-side encryption to encrypt the EBS snapshot.
Why it's wrong here
EBS snapshots are stored in Amazon S3, but their encryption is managed by the EBS service and AWS KMS, not by S3 server-side encryption (SSE) settings. When you create a snapshot from an encrypted EBS volume, the snapshot is automatically encrypted with the same KMS key used for the volume, or you can specify a different key during snapshot creation. Applying S3 SSE to an existing EBS snapshot is not possible because the snapshot's encryption is inherited from EBS; S3 SSE is irrelevant to how EBS snapshots are encrypted.
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 and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Amazon Web Services exam blueprint
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