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:::my-data-lake/*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "glue:StartJobRun",
        "glue:GetJobRun"
      ],
      "Resource": "arn:aws:glue:us-east-1:123456789012:job/my-etl-job"
    }
  ]
}
```

A data engineer uses the IAM policy above for an AWS Lambda function that processes data in S3 and triggers an AWS Glue job. The Lambda function is unable to start the Glue job. What is the most likely cause?

⚠ Common exam trap

The trap here is that candidates focus on S3 permissions (options B and D) because the Lambda processes S3 data, but the actual failure is the missing IAM permission required to delegate a role to AWS Glue, which is a subtle but critical detail in cross-service orchestration.

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 include iam:PassRole permission.

The Lambda function needs to pass an IAM role to AWS Glue when starting a job, which requires the `iam:PassRole` permission. Without this permission, the `StartJobRun` API call fails even if the Lambda has permissions to invoke Glue. The policy shown lacks this critical permission, making option C the correct answer.

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 Glue job name in the resource ARN is misspelled.
Why it's wrong here
The exhibit does not indicate misspelling.
✗
The policy does not allow s3:PutObject on the bucket.
Why it's wrong here
The policy includes s3:PutObject.
✓
The policy does not include iam:PassRole permission.
Why this is correct
To start a Glue job, Lambda must pass an execution role; iam:PassRole is required.
✗
The policy does not include s3:GetObject on the bucket.
Why it's wrong here
The policy includes s3:GetObject on the bucket.

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

Related to this question