AWS Serverless Architecture and AWS Lambda 4

Question 1

A Lambda function needs to process messages from an SQS queue but should stop retrying a message after 3 failed attempts. What should you configure?

Accepted Answer

Configure a Dead Letter Queue (DLQ) on the SQS event source mapping with maxReceiveCount=3

Answer

Setting maxReceiveCount on the SQS event source mapping's redrive policy sends messages to a DLQ after the specified number of failed processing attempts.

Question 2

Which Lambda feature allows you to run a portion of traffic on a new version while keeping most traffic on a stable version?

Accepted Answer

Lambda Aliases with weighted routing

Answer

Lambda aliases support weighted routing, allowing you to split traffic between two function versions for canary or blue/green deployments.

Question 3

A Lambda function reads from DynamoDB Streams. The function is failing and the stream iterator keeps replaying the same batch. What is the most likely cause?

Accepted Answer

The Lambda function is throwing an unhandled exception, causing the batch to retry

Answer

When a Lambda function throws an unhandled exception processing a DynamoDB Stream batch, the batch is retried until it succeeds or the retention period expires.

Question 4

What is the maximum execution timeout for an AWS Lambda function?

Accepted Answer

15 minutes

Answer

AWS Lambda functions have a maximum execution timeout of 15 minutes (900 seconds).

Question 5

An application uses Lambda with API Gateway. During a traffic spike, some requests receive 429 errors. What is the root cause?

Accepted Answer

Both A and C are possible causes

Answer

429 Too Many Requests errors from API Gateway + Lambda can result from API Gateway throttling limits OR Lambda concurrency limits being exhausted.

AWS Practice Test

AWS Practice Test

AWS Serverless Architecture and AWS Lambda 4