MLS-C01 Data Engineering Practice Question

Exhibit

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Resources": {
    "MyBucket": {
      "Type": "AWS::S3::Bucket",
      "Properties": {
        "LifecycleConfiguration": {
          "Rules": [
            {
              "Id": "ArchiveRule",
              "Status": "Enabled",
              "Transition": {
                "StorageClass": "GLACIER",
                "TransitionInDays": 30
              },
              "ExpirationInDays": 365
            }
          ]
        }
      }
    }
  }
}

Refer to the exhibit. A CloudFormation template creates an S3 bucket. The data engineering team stores daily log files in this bucket and queries them using Amazon Athena. After 30 days, queries on logs older than 30 days start failing with 'Access Denied' errors. What is the MOST likely reason?

⚠ Common exam trap

Many exam-takers confuse 'Access Denied' errors with permission issues (bucket policies or IAM) rather than recognizing that the error is caused by the storage class transition to GLACIER, which makes objects unreadable by Athena without restoration.

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 lifecycle rule transitions objects to GLACIER after 30 days, making them inaccessible to Athena.

Amazon Athena reads data directly from S3 and does not support querying objects stored in the GLACIER storage class because GLACIER objects are not retrievable in real time. The lifecycle rule transitions objects to GLACIER after 30 days, so when Athena attempts to read those older objects, it receives 'Access Denied' errors because the objects are no longer in a queryable storage class.

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 lifecycle rule transitions objects to GLACIER after 30 days, making them inaccessible to Athena.
Why this is correct
Athena cannot query GLACIER objects; they must be restored first.
✗
The bucket uses default encryption with SSE-S3, which Athena does not support.
Why it's wrong here
Athena supports SSE-S3.
✗
The lifecycle rule deletes objects after 30 days.
Why it's wrong here
ExpirationInDays is 365, not 30.
✗
The bucket policy denies access to objects older than 30 days.
Why it's wrong here
No bucket policy is defined in the template.

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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