What should the Solutions Architect recommend?
Migrate the existing EC2 instances to a serverless deployment using AWS Lambda functions
Change the Classic Load Balancer to an Application Load Balancer
Replace the application tier with m4.large instances in an Auto Scaling group
Replace the application tier with 4 m4.2xlarge instances
Explanations:
Migrating to AWS Lambda would require a complete redesign of the application to be serverless. Additionally, Lambda is better suited for event-driven workloads, not for applications with persistent state like this one.
Changing the Classic Load Balancer to an Application Load Balancer may provide better routing and advanced features, but it does not address the root cause of performance issues related to instance failures or scaling.
Replacing the existing m4.xlarge instances with m4.large instances in an Auto Scaling group helps to automatically adjust capacity in response to changing demand, increasing fault tolerance while minimizing costs.
Replacing the application tier with 4 m4.2xlarge instances would increase cost and does not provide scalability or fault tolerance features, which are essential to ensure system reliability.
If I had to guess, I’d say the answer is:
Replace the application tier with m4.large instances in an Auto Scaling group