AWS Certified Developer – Associate — Question 197

An ecommerce company is using an AWS Lambda function behind Amazon API Gateway as its application tier. To process orders during checkout, the application calls a POST API from the frontend. The POST API invokes the Lambda function asynchronously. In rare situations, the application has not processed orders. The Lambda application logs show no errors or failures.

What should a developer do to solve this problem?

Answer options

• A. Inspect the frontend logs for API failures. Call the POST API manually by using the requests from the log file.
• B. Create and inspect the Lambda dead-letter queue. Troubleshoot the failed functions. Reprocess the events.
• C. Inspect the Lambda logs in Amazon CloudWatch for possible errors. Fix the errors.
• D. Make sure that caching is disabled for the POST API in API Gateway.

Correct answer: B

Explanation

The correct answer is B because creating and inspecting the dead-letter queue allows the developer to identify and troubleshoot any failed invocations of the Lambda function. The other options do not address the issue of asynchronous failures; inspecting logs or disabling caching may not reveal the underlying problem of unprocessed events.