MLS-C01 Modeling Practice Question

Exhibit

Refer to the exhibit.
```
{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Effect": "Allow",
            "Action": [
                "sagemaker:CreateTrainingJob",
                "sagemaker:DescribeTrainingJob"
            ],
            "Resource": "*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:GetObject"
            ],
            "Resource": "arn:aws:s3:::my-bucket/training/*"
        },
        {
            "Effect": "Allow",
            "Action": [
                "s3:PutObject"
            ],
            "Resource": "arn:aws:s3:::my-bucket/output/*"
        }
    ]
}
```

A data scientist is setting up an IAM role for an Amazon SageMaker training job. The policy shown is attached to the role. The training job fails with an access denied error when trying to read the training data from s3://my-bucket/training/data.csv. What is the most likely reason?

⚠ Common exam trap

Many exam-takers assume the IAM policy alone determines access, overlooking that resource-based policies (like S3 bucket policies) can override IAM permissions with explicit denies, especially when the bucket policy is not shown in the question.

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 bucket policy on my-bucket denies access to the IAM role

The IAM policy shown grants s3:GetObject access to the bucket and object, but the training job still fails with an access denied error. The most likely cause is that the bucket policy on my-bucket explicitly denies access to the IAM role, overriding the IAM policy's allow. In AWS, an explicit deny in a resource-based policy (bucket policy) takes precedence over any allow in an identity-based policy (IAM role policy), causing the access denied error despite the IAM policy appearing sufficient.

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 bucket policy on my-bucket denies access to the IAM role
Why this is correct
The IAM policy allows GetObject, but the bucket policy may have a deny rule that overrides the allow.
✗
The training job is using a different IAM role
Why it's wrong here
The training job would use the specified role; if it used a different role, the error would still be access denied but the exhibit shows the role's policy.
✗
The IAM policy is missing the s3:ListBucket permission
Why it's wrong here
S3 GetObject does not require ListBucket; the error is about reading the object, not listing.
✗
The IAM role does not have permission to access the bucket location
Why it's wrong here
The policy explicitly allows GetObject on the training prefix, which includes data.csv.

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 Modeling Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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