MLS-C01 Data Engineering Practice Question
Exhibit
Refer to the exhibit.
```json
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Action": "s3:PutObject",
"Resource": "arn:aws:s3:::my-bucket/*",
"Condition": {
"StringEquals": {
"s3:x-amz-server-side-encryption": "AES256"
}
}
}
]
}
```A data engineer is configuring an IAM policy to allow users to upload objects to an S3 bucket only if the objects are encrypted using SSE-S3. However, users are getting AccessDenied errors when uploading objects without specifying encryption. What is the most likely 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 condition requires encryption to be specified, but the upload does not specify it
The policy allows PutObject only when encryption is AES256, but denies when no encryption is specified because the condition is not met. Option A is wrong because it's not a service control policy; Option C is wrong because the bucket policy is not shown; Option D is wrong because the condition checks for AES256, not KMS.
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 condition should check for aws:SourceIp instead of encryption
Why it's wrong here
Not relevant; the condition is correctly used.
- ✓
The condition requires encryption to be specified, but the upload does not specify it
Why this is correct
The condition requires s3:x-amz-server-side-encryption to be AES256, so without it, access is denied.
- ✗
The policy is attached to the wrong IAM user
Why it's wrong here
Policy attachment is not the issue; it's the condition.
- ✗
The bucket policy denies all PutObject without encryption
Why it's wrong here
The bucket policy is not shown; the IAM policy allows only with encryption.
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
Related to this question
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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.