AWS Certified Solutions Architect – Professional — Question 463

A 3-Ber e-commerce web application is currently deployed on-premises, and will be migrated to AWS for greater scalability and elasticity. The web tier currently shares read-only data using a network distributed file system. The app server tier uses a clustering mechanism for discovery and shared session state that depends on IP multicast. The database tier uses shared-storage clustering to provide database failover capability, and uses several read slaves for scaling. Data on all servers and the distributed file system directory is backed up weekly to off-site tapes.
Which AWS storage and database architecture meets the requirements of the application?

Answer options

• A. Web servers: store read-only data in S3, and copy from S3 to root volume at boot time. App servers: share state using a combination of DynamoDB and IP unicast. Database: use RDS with multi-AZ deployment and one or more read replicas. Backup: web servers, app servers, and database backed up weekly to Glacier using snapshots.
• B. Web servers: store read-only data in an EC2 NFS server, mount to each web server at boot time. App servers: share state using a combination of DynamoDB and IP multicast. Database: use RDS with multi- AZ deployment and one or more Read Replicas. Backup: web and app servers backed up weekly via AMIs, database backed up via DB snapshots.
• C. Web servers: store read-only data in S3, and copy from S3 to root volume at boot time. App servers: share state using a combination of DynamoDB and IP unicast. Database: use RDS with multi-AZ deployment and one or more Read Replicas. Backup: web and app servers backed up weekly via AMIs, database backed up via DB snapshots.
• D. Web servers: store read-only data in S3, and copy from S3 to root volume at boot time App servers: share state using a combination of DynamoDB and IP unicast. Database: use RDS with multi-AZ deployment. Backup: web and app servers backed up weekly via AMIs, database backed up via DB snapshots.

Correct answer: A

Explanation

Option A is correct because AWS VPC does not natively support IP multicast, requiring the application servers to use IP unicast alongside DynamoDB for session state. RDS with multi-AZ deployment and read replicas perfectly replaces the on-premises shared-storage database clustering and read slaves, while backing up snapshots to Glacier provides a secure, cost-effective replacement for weekly off-site tape backups.