AWS Certified Solutions Architect – Professional — Question 667

Your company hosts a social media site supporting users in multiple countries. You have been asked to provide a highly available design tor the application that leverages multiple regions tor the most recently accessed content and latency sensitive portions of the wet) site The most latency sensitive component of the application involves reading user preferences to support web site personalization and ad selection.
In addition to running your application in multiple regions, which option will support this application's requirements?

Answer options

• A. Serve user content from S3. CloudFront and use Route53 latency-based routing between ELBs in each region Retrieve user preferences from a local DynamoDB table in each region and leverage SQS to capture changes to user preferences with SOS workers for propagating updates to each table.
• B. Use the S3 Copy API to copy recently accessed content to multiple regions and serve user content from S3. CloudFront with dynamic content and an ELB in each region Retrieve user preferences from an ElasticCache cluster in each region and leverage SNS notifications to propagate user preference changes to a worker node in each region.
• C. Use the S3 Copy API to copy recently accessed content to multiple regions and serve user content from S3 CloudFront and Route53 latency-based routing Between ELBs In each region Retrieve user preferences from a DynamoDB table and leverage SQS to capture changes to user preferences with SOS workers for propagating DynamoDB updates.
• D. Serve user content from S3. CloudFront with dynamic content, and an ELB in each region Retrieve user preferences from an ElastiCache cluster in each region and leverage Simple Workflow (SWF) to manage the propagation of user preferences from a centralized OB to each ElastiCache cluster.

Correct answer: A

Explanation

Option A is correct because utilizing local DynamoDB tables in each region combined with SQS-driven replication provides the lowest possible read latency for user preferences while maintaining high availability. Route53 latency-based routing efficiently directs users to the nearest regional ELB, and CloudFront caches static and dynamic assets close to the users. Other options either rely on inefficient S3 Copy APIs, lack multi-region database write propagation, or use ElastiCache with overly complex synchronization mechanisms like SWF or SNS that do not guarantee the same durability and performance characteristics as DynamoDB with SQS.