DEA-C01 Data Store Management Practice Question
A company is using Amazon S3 to store sensitive data. The security team requires that all data be encrypted at rest using a customer-managed AWS KMS key. The data engineer must ensure that only a specific IAM role can decrypt the data. Which policy should the data engineer attach to the KMS key?
⚠ Common exam trap
The DEA-C01 exam often tests the misconception that IAM policies alone can control KMS key access, but the correct approach is to use a KMS key policy that explicitly grants the required action to the specific principal.
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
✓
A KMS key policy that allows the IAM role to perform kms:Decrypt
KMS key policies are the primary mechanism for controlling access to a customer-managed KMS key. By specifying the IAM role as a principal in the key policy and granting kms:Decrypt, you ensure that only that role can decrypt data encrypted with this key, regardless of any IAM policies that might otherwise allow broader access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A KMS key policy that allows the IAM role to perform kms:Decrypt
Why this is correct
KMS key policies grant permissions to use the key.
- ✗
An IAM user policy that allows kms:Decrypt for the specific key
Why it's wrong here
Should be attached to the role, not a user.
- ✗
An IAM policy attached to the role that allows kms:Decrypt
Why it's wrong here
The KMS key policy must also allow the role to use the key.
- ✗
An S3 bucket policy that denies access unless encryption is used
Why it's wrong here
Bucket policy controls S3 access, not KMS permissions.
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.