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Answer: Create an AWS Lambda function to retrieve user information from Amazon DynamoDB. Create an Amazon API Gateway endpoint to accept RESTful APIs. Send the API calls to the Lambda function., Create an Amazon Cognito user pool to authenticate users., Use AWS Amplify to serve the frontend web content with HTML, CSS, and JS. Use an integrated Amazon CloudFront configuration.
## Explanation **Correct Answers: A, C, E** ### Why A is correct: - **AWS Lambda + API Gateway + DynamoDB** provides a serverless, cost-effective backend solution - Lambda charges only when code runs (pay-per-use), ideal for unpredictable traffic patterns - DynamoDB offers on-demand capacity for unpredictable workloads - No need to provision and pay for idle compute resources ### Why C is correct: - **Amazon Cognito User Pool** is designed for user authentication and authorization - Perfect for subscription-based access control - Manages user sign-up, sign-in, and access control - Integrates with Lambda and API Gateway for secure API access ### Why E is correct: - **AWS Amplify** with CloudFront provides a cost-effective frontend hosting solution - Amplify offers simplified deployment and hosting for static web content - CloudFront provides global content delivery with caching - Static content (HTML, CSS, JS) is ideal for S3/CloudFront hosting - Lower cost than running web servers for static content ### Why other options are incorrect: **B is incorrect:** - Amazon ECS with ALB requires running containers continuously, which is not cost-effective for unpredictable traffic - RDS requires provisioned database capacity, which is more expensive than DynamoDB for this use case - Mixing ECS with Lambda via API Gateway creates unnecessary complexity **D is incorrect:** - Amazon Cognito Identity Pool is for providing temporary AWS credentials to access AWS services, not for user authentication - User Pool (C) is the correct choice for authentication **F is incorrect:** - S3 static hosting with PHP won't work - PHP requires server-side processing which S3 cannot provide - S3 can only host static files (HTML, CSS, JS, images) - PHP would require a server (like EC2 or Lambda) to execute ### Cost Optimization Strategy: 1. **Serverless backend** (A) eliminates idle compute costs 2. **Managed authentication** (C) reduces operational overhead 3. **Static frontend hosting** (E) with CDN minimizes delivery costs 4. **Pay-per-use pricing** aligns with unpredictable traffic patterns 5. **No infrastructure management** reduces operational costs
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A company wants to build a web application on AWS. Client access requests to the website are not predictable and can be idle for a long time. Only customers who have paid a subscription fee can have the ability to sign in and use the web application.
Which combination of steps will meet these requirements MOST cost-effectively? (Choose three.)
A
Create an AWS Lambda function to retrieve user information from Amazon DynamoDB. Create an Amazon API Gateway endpoint to accept RESTful APIs. Send the API calls to the Lambda function.
B
Create an Amazon Elastic Container Service (Amazon ECS) service behind an Application Load Balancer to retrieve user information from Amazon RDS. Create an Amazon API Gateway endpoint to accept RESTful APIs. Send the API calls to the Lambda function.
C
Create an Amazon Cognito user pool to authenticate users.
D
Create an Amazon Cognito identity pool to authenticate users.
E
Use AWS Amplify to serve the frontend web content with HTML, CSS, and JS. Use an integrated Amazon CloudFront configuration.
F
Use Amazon S3 static web hosting with PHP, CSS, and JS. Use Amazon CloudFront to serve the frontend web content.