MLS-C01 Data Engineering Practice Question
Exhibit
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": [
"s3:GetObject",
"s3:PutObject"
],
"Resource": "arn:aws:s3:::data-bucket/*"
},
{
"Effect": "Allow",
"Action": [
"kms:Decrypt",
"kms:GenerateDataKey"
],
"Resource": "arn:aws:kms:us-east-1:123456789012:key/abc123"
},
{
"Effect": "Allow",
"Action": [
"glue:GetTable",
"glue:UpdateTable"
],
"Resource": "arn:aws:glue:us-east-1:123456789012:catalog"
}
]
}Refer to the exhibit. A data engineer has attached this IAM policy to an IAM role used by an AWS Glue ETL job. The job reads from an S3 bucket (data-bucket) that is encrypted with SSE-KMS using the key arn:aws:kms:us-east-1:123456789012:key/abc123, transforms the data, and writes the result to a different S3 bucket (output-bucket) encrypted with a different KMS key (arn:aws:kms:us-east-1:123456789012:key/xyz789). When the job runs, it fails with an access denied error. What is the cause?
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
✓
The policy does not grant kms:Encrypt permission for the output bucket's KMS key.
The job fails because the IAM policy grants kms:Decrypt and kms:GenerateDataKey for the input bucket's KMS key (abc123) but does not grant kms:Encrypt or kms:GenerateDataKey for the output bucket's KMS key (xyz789). To write encrypted data to the output bucket, the AWS Glue job must have permission to encrypt using the output KMS key. Option D is correct because the missing kms:Encrypt permission causes the access denied error. Option A is incorrect because the policy includes s3:GetObject for the input bucket. Option B is incorrect because Glue catalog permissions are not relevant to the encryption error. Option C is incorrect because the error is due to missing KMS permissions for the output bucket, not because the policy does not include s3:PutObject.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The policy does not include s3:GetObject permission for the output bucket.
Why it's wrong here
The job reads from input bucket, not output; output requires PutObject.
- ✗
The policy does not include glue:CreateTable permission.
Why it's wrong here
The policy includes glue:UpdateTable, but the job may need create; however, the error is likely KMS.
- ✗
The policy does not include s3:PutObject permission for the output bucket.
Why it's wrong here
The policy grants s3:PutObject on data-bucket, but the output bucket is different.
- ✓
The policy does not grant kms:Encrypt permission for the output bucket's KMS key.
Why this is correct
To write to an SSE-KMS encrypted bucket, the role needs kms:Encrypt or kms:GenerateDataKey for that key.
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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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.