Multi-AZ scalable web application architecture using AWS ALB, Auto Scaling Groups, and RDS MySQL with synchronous replication across us-east-1a and us-east-1b. Internet traffic routes through an Internet Gateway to an Application Load Balancer spanning both availability zones, distributing requests to Node.js EC2 t3.medium instances managed by Auto Scaling Groups with CPU-based policies. Application servers retrieve database credentials from Secrets Manager via IAM roles and connect to RDS MySQL Primary and Standby instances, which maintain real-time replication for fault tolerance. CloudWatch CPU alarms trigger Auto Scaling Group policies to dynamically adjust capacity, ensuring consistent performance during traffic spikes while minimizing idle costs. Fork this diagram to customize subnets, instance types, or add caching layers like ElastiCache for production deployments.