AIF-C01 Fundamentals of AI and ML Practice Question

Exhibit

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

Refer to the exhibit. A SageMaker training job fails with an 'AccessDenied' error when trying to read files from the S3 bucket 'my-training-data'. The IAM role used by the training job has the policy shown. What is the most likely reason for the failure?

⚠ Common exam trap

AWS often tests the misconception that only s3:GetObject is needed for reading from S3, but the SDK's underlying ListBucket call is required for object discovery, especially when using prefixes or manifest files.

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 the s3:ListBucket action

The IAM policy grants s3:GetObject but not s3:ListBucket. When a SageMaker training job reads files from S3, the SageMaker SDK or framework (e.g., TensorFlow, PyTorch) often performs a ListBucket call first to enumerate objects in the prefix. Without s3:ListBucket, the SDK cannot discover the files, resulting in an AccessDenied error even though 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 bucket policy requires encryption in transit
Why it's wrong here
Encryption requirements would cause a different error (e.g., 'AccessDenied' with encryption context).
✗
The training job is using the wrong AWS region
Why it's wrong here
Region mismatch would cause a 'NoSuchBucket' error or connection timeout, not AccessDenied.
✗
The policy does not include the s3:PutObject action
Why it's wrong here
PutObject is for writing, not reading, and is not needed for training input.
✓
The policy does not include the s3:ListBucket action
Why this is correct
Without ListBucket, SageMaker cannot list the contents of the bucket to verify object existence.

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

AIF-C01 Fundamentals of AI and ML Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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