AWS Certified Developer – Associate — Question 233

A developer is creating an AWS Lambda function to process streaming data from an Amazon Kinesis data stream. When the Lambda function parses the data and encounters a malformed record from the stream, the Lambda function exits with an error.

The developer is observing duplicate records downstream from the function. When the developer uses a different client to examine the Kinesis data stream output, no duplicate records are visible in the stream.

What is the reason for the duplicate records?

Answer options

• A. The Lambda function did not advance the Kinesis data stream pointer to the next record after the error.
• B. The Lambda event source used asynchronous invocation.
• C. The Lambda function did not handle the error, and the Lambda service attempted to reprocess the data.
• D. The Lambda function did not keep up with the amount of data that was coming from the Kinesis data stream.

Correct answer: C

Explanation

The correct answer is C because when the Lambda function encounters an unhandled error, the Lambda service retries processing the same record, leading to duplicates. Option A is incorrect because it does not directly cause duplicates; advancing the pointer would prevent reprocessing. Option B is not relevant here, as asynchronous invocation does not explain the observed behavior. Option D is also wrong since the issue is related to error handling, not the function's processing speed.