MLS-C01 Data Engineering Practice Question

Exhibit

Refer to the exhibit.

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:GetObject",
        "s3:PutObject"
      ],
      "Resource": "arn:aws:s3:::example-bucket/*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "glue:StartJobRun",
        "glue:GetJobRun"
      ],
      "Resource": "*"
    }
  ]
}

A data engineer is troubleshooting an AWS Glue job that reads from an S3 bucket and writes to another S3 bucket. The job fails with an 'Access Denied' error when trying to write to the output bucket. The IAM policy attached to the Glue service role is shown. What is the MOST likely cause of the failure?

⚠ Common exam trap

The trap here is that candidates may overlook the Resource field and assume the error is due to missing actions or user permissions, rather than recognizing that the IAM policy must explicitly list the destination bucket ARN for the write operation to succeed.

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 output bucket is not listed in the Resource of the IAM policy

The IAM policy attached to the Glue service role explicitly lists the output bucket in the Resource field. If the output bucket is not listed, the Glue job will receive an 'Access Denied' error when attempting to write to it, because the policy does not grant the necessary s3:PutObject permission for that bucket. This is the most direct cause of the failure.

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 user who runs the job does not have S3 permissions
Why it's wrong here
The job runs under the service role, not the user.
✗
The Glue job role does not have permissions to start a job run
Why it's wrong here
The policy allows glue:StartJobRun.
✓
The output bucket is not listed in the Resource of the IAM policy
Why this is correct
The policy only allows PutObject on example-bucket, not the output bucket.
✗
The S3 bucket policy denies access to the Glue service
Why it's wrong here
There is no indication of bucket policy; the IAM policy is insufficient.

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

MLS-C01 Data Engineering Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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