MLA-C01 Data Preparation for Machine Learning Practice Question

Exhibit

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

Refer to the exhibit. A data scientist is trying to use AWS Glue to read data from the S3 bucket `ml-data-bucket`. The Glue job fails with an access denied error. What is the most likely cause?

⚠ Common exam trap

AWS often tests the subtle distinction between bucket-level permissions (like s3:ListBucket) and object-level permissions (like s3:GetObject), where candidates assume that granting GetObject on objects is sufficient for reading data, forgetting that listing the bucket is a prerequisite for discovering those objects.

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 s3:ListBucket permission on the bucket

The error occurs because the IAM policy attached to the Glue job role grants s3:GetObject on the bucket objects (via the `arn:aws:s3:::ml-data-bucket/*` resource) but does not include the s3:ListBucket permission on the bucket itself (`arn:aws:s3:::ml-data-bucket`). When AWS Glue reads data from S3, it first performs a ListBucket operation to enumerate objects in the bucket or prefix, and without that permission, the request is denied even if GetObject is allowed.

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 allows s3:PutObject but the job only reads
Why it's wrong here
Excess permissions do not cause access denied.
✗
The policy does not specify the bucket ARN without /*
Why it's wrong here
The bucket ARN is correctly specified for object actions.
✗
The Glue job role does not have the required permissions
Why it's wrong here
The error is due to missing ListBucket, not missing role.
✓
The policy does not include s3:ListBucket permission on the bucket
Why this is correct
Glue needs ListBucket to discover objects in 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

MLA-C01 Data Preparation for Machine Learning Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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