AWS Certified Solutions Architect – Associate (SAA-C03) — Question 652

A solutions architect is designing a shared storage solution for a web application that is deployed across multiple Availability Zones. The web application runs on Amazon EC2 instances that are in an Auto Scaling group. The company plans to make frequent changes to the content. The solution must have strong consistency in returning the new content as soon as the changes occur.

Which solutions meet these requirements? (Choose two.)

Answer options

• A. Use AWS Storage Gateway Volume Gateway Internet Small Computer Systems Interface (iSCSI) block storage that is mounted to the individual EC2 instances.
• B. Create an Amazon Elastic File System (Amazon EFS) file system. Mount the EFS file system on the individual EC2 instances.
• C. Create a shared Amazon Elastic Block Store (Amazon EBS) volume. Mount the EBS volume on the individual EC2 instances.
• D. Use AWS DataSync to perform continuous synchronization of data between EC2 hosts in the Auto Scaling group.
• E. Create an Amazon S3 bucket to store the web content. Set the metadata for the Cache-Control header to no-cache. Use Amazon CloudFront to deliver the content.

Correct answer: B, E

Explanation

Amazon EFS provides a shared file system that supports concurrent access across multiple Availability Zones with strong consistency, making it ideal for EC2 instances in an Auto Scaling group. Storing content in Amazon S3 combined with Amazon CloudFront and a 'no-cache' Cache-Control header ensures that requests bypass edge caches to fetch the latest strongly consistent data directly from S3. Other options like EBS cannot be easily shared across multiple AZs concurrently, AWS Storage Gateway is not designed for this high-performance web use case, and AWS DataSync is meant for data migration rather than real-time application synchronization.