You are migrating a two-tier, stateful web application to AWS using Aurora PostgreSQL for the database, EC2 Auto Scaling for the application tier, and Elastic Load Balancing. The application requires a consistent user experience as both the application and database tiers scale. Which configuration will provide consistent session behavior and allow both tiers to scale appropriately?

The correct option ensures both application and database tiers scale appropriately while maintaining consistent session behavior. Aurora Auto Scaling for Aurora Replicas allows the database to scale read capacity automatically based on demand, which is crucial for a web application. An Application Load Balancer (ALB) is suitable for HTTP/HTTPS traffic and offers sticky sessions, which route a user's requests to the same EC2 instance, preserving session state. Round-robin routing is a standard, effective load balancing algorithm for distributing requests evenly. Incorrect options: Enabling Aurora Auto Scaling for Aurora writers is generally not recommended for scaling read-heavy web applications, as the writer instance handles writes and typically doesn't benefit from auto-scaling in the same way replicas do for reads. Network Load Balancers (NLBs) operate at Layer 4 and do not support sticky sessions based on application-level cookies, which are essential for maintaining consistent user experience in stateful web applications. Using a Network Load Balancer with sticky sessions is incorrect because NLBs do not support application-level sticky sessions.