MLS-C01 Data Engineering Practice Question
A company is building a data pipeline to process sensitive customer data. The pipeline uses AWS Glue for ETL and stores results in Amazon S3. The security team requires that all data be encrypted at rest in S3 using customer-managed AWS KMS keys. Additionally, the Glue job must be able to write encrypted data to S3. What should the data engineer do to meet these requirements?
⚠ Common exam trap
Many candidates assume an S3 bucket policy alone can enforce encryption without realizing that the IAM role performing the write must also have explicit KMS permissions for the customer-managed key.
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
✓
Attach a policy to the Glue job's IAM role that includes kms:GenerateDataKey and kms:Decrypt actions for the KMS key.
AWS Glue jobs use an IAM role to interact with AWS services. To write encrypted data to S3 using a customer-managed AWS KMS key, the IAM role must have permissions for `kms:GenerateDataKey` (to request a data key for encryption) and `kms:Decrypt` (to decrypt the data key when reading or writing). This allows the Glue job to encrypt objects at rest in S3 with the specified KMS key, meeting the security team's requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Attach a policy to the Glue job's IAM role that includes kms:GenerateDataKey and kms:Decrypt actions for the KMS key.
Why this is correct
These permissions allow Glue to encrypt and decrypt data using the KMS key.
- ✗
Use S3 server-side encryption with customer-provided keys (SSE-C).
Why it's wrong here
SSE-C requires the client to provide the encryption key, which is not suitable for Glue.
- ✗
Use S3 server-side encryption with SSE-S3, which is enabled by default.
Why it's wrong here
SSE-S3 uses Amazon-managed keys, not customer-managed.
- ✗
Configure an S3 bucket policy to enforce encryption and attach it to the Glue job's IAM role.
Why it's wrong here
Bucket policy controls permissions but does not grant KMS actions.
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 MLS-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 MLS-C01 exam.