Answer: Migrate the web tier to Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer., Migrate the database to an Amazon RDS Multi-AZ deployment.

## Explanation **Correct Answers: A and C** **A. Migrate the web tier to Amazon EC2 instances in an Auto Scaling group behind an Application Load Balancer.** - This approach improves resiliency for the web tier by: - Using Auto Scaling to automatically add/remove instances based on demand - Distributing traffic across multiple instances via Application Load Balancer - Providing high availability across Availability Zones - Minimizing application changes (lift-and-shift approach) **C. Migrate the database to an Amazon RDS Multi-AZ deployment.** - This approach improves database resiliency by: - Providing automatic failover to a standby replica in another Availability Zone - Maintaining high availability for the MySQL database - Minimizing application changes (RDS is MySQL-compatible) - Automated backups and maintenance **Why other options are incorrect:** **B. Migrate the database to Amazon EC2 instances in an Auto Scaling group behind a Network Load Balancer.** - This is not suitable for databases because: - Databases are stateful and cannot be load balanced in this way - Auto Scaling with databases requires complex replication and failover mechanisms - Network Load Balancer is not designed for database workloads **D. Migrate the web tier to an AWS Lambda function.** - This would require significant application changes (rewriting as serverless) - Contradicts the requirement to "minimize changes to the application" **E. Migrate the database to an Amazon DynamoDB table.** - This would require significant application changes (NoSQL vs SQL) - DynamoDB is a NoSQL database, while the application uses MySQL (SQL) - Would require rewriting database queries and data model **Key Requirements Met:** 1. **Minimize changes to the application**: Both options A and C allow lift-and-shift migration 2. **Improve application resiliency**: Auto Scaling + ALB for web tier, RDS Multi-AZ for database 3. **MySQL compatibility**: RDS supports MySQL with minimal changes 4. **Multi-tier architecture preserved**: Web tier and database tier remain separate as in original design

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