DEA-C01 Data Ingestion and Transformation Practice Question

Exhibit

Refer to the exhibit.

{
  "Events": [
    {
      "EventID": "1",
      "EventVersion": "1.0",
      "EventSource": "aws:s3",
      "AwsRegion": "us-east-1",
      "EventName": "ObjectCreated:Put",
      "UserIdentity": {
        "principalId": "AWS:AIDAEXAMPLE"
      },
      "RequestParameters": {
        "sourceIPAddress": "192.0.2.1"
      },
      "ResponseElements": {
        "x-amz-request-id": "EXAMPLE123"
      },
      "S3": {
        "s3SchemaVersion": "1.0",
        "bucket": {
          "name": "source-bucket",
          "arn": "arn:aws:s3:::source-bucket"
        },
        "object": {
          "key": "data/file.csv",
          "size": 1024,
          "eTag": "abc123",
          "sequencer": "0055AED6DCD90281E5"
        }
      }
    }
  ]
}

Refer to the exhibit. A company uses S3 Event Notifications to trigger an AWS Lambda function whenever a new object is uploaded to an S3 bucket. The Lambda function processes the file and moves it to a different bucket. Recently, the function has been failing intermittently. The engineer checks the Lambda CloudWatch logs and sees the above event. What is the MOST likely cause of the intermittent failures?

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 S3 event notifications are not guaranteed to be delivered exactly once, causing duplicate processing.

S3 Event Notifications are asynchronous and may be duplicated or delivered out of order, causing race conditions. Option A is wrong because the event has all required fields. Option B is wrong because the bucket name is valid. Option D is wrong because the event format is correct.

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 event JSON is malformed; the 'EventSource' should be 's3.amazonaws.com'.
Why it's wrong here
EventSource 'aws:s3' is correct.
✗
The S3 bucket name contains a hyphen, which is not allowed.
Why it's wrong here
Hyphens are allowed.
✓
The S3 event notifications are not guaranteed to be delivered exactly once, causing duplicate processing.
Why this is correct
At-least-once delivery can cause issues.
✗
The event is missing the 'object:versionId' field.
Why it's wrong here
Not required for PutObject.

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

DEA-C01 Data Ingestion and Transformation Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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