Exam AWS Certified Developer - Associate DVA-C02 topic 1 question 30 discussion

B. Create an AWS Lambda function that uses Amazon Simple Email Service (Amazon SES) to send the email notification. Add an Amazon Cognito post authentication Lambda trigger for the function. The most operationally efficient solution for sending login activity notifications by email for Amazon Cognito user pools is to use a Lambda trigger that is automatically invoked by Amazon Cognito every time a user logs in. This eliminates the need for client-side calls to an API or log subscription filter. A Lambda function can be used to send email notifications using Amazon SES. Option B satisfies these requirements and is the most operationally efficient solution.

B https://docs.aws.amazon.com/cognito/latest/developerguide/user-pool-lambda-post-authentication.html

A) Eliminated - the API Gateway needs to be explicitly invoked from the client. not operationally efficient B) Correct - Post-authentication triggers are built-in Cognito features that automatically execute a Lambda function after a user logs in. C) Eliminated - less efficient because it requires setting up CloudWatch Logs for Cognito, creating subscription filters, and maintaining log processing infrastructure D) Eliminated - highly complex and introduces multiple components (Kinesis, Firehose, Lambda),

==> Discard A: Requires client-side API calls, which are less secure and operationally inefficient (enhance security, validate in BE, ...) compared to server-side triggers. ==> Discard C: Relies on CloudWatch Logs and filters, which add unnecessary complexity and are not directly tied to Cognito's login events. ==> Discard D: Involves Kinesis Data Firehose for log streaming, which is over-engineered and introduces additional cost and latency for a simple notification task. B: Uses Cognito's native post-authentication trigger, which is the most secure, integrated, and operationally efficient method for sending email notifications after successful logins.

Option B is absolutely correct. The Lambda function is triggered by Coginito whenever a user log in. The Lambda function then sends email notification to the user using Amazon SES.

B is the correct answer.

Amazon Cognito user pools integrate with API Gateway or ALB Process is: user athenticate with CUP, receive JWT (token), then pass to API Gateway API Gateway will evaluate JWT wwith CUP, if it is valid, allow access to Lambda (have a duty to send email)

B https://www.examtopics.com/discussions/amazon/view/78944-exam-aws-certified-developer-associate-topic-1-question-9/