AWS Cloud ap-northeast-2 Production VPC (10.0.0.0/16) IGW Internet Gateway Public Subnet (10.0.1.0/24) — AZ-a NAT NAT Gateway ALB Application LB Private Subnet (10.0.10.0/24) — AZ-a Auto Scaling Group EC2 Web Server 1 EC2 Web Server 2 EC2 (scaling) Public Subnet (10.0.2.0/24) — AZ-c NAT NAT Gateway ALB Application LB Cross-AZ Private Subnet (10.0.20.0/24) — AZ-c Auto Scaling Group EC2 Web Server 3 EC2 Web Server 4 EC2 (scaling) DB Subnet (10.0.100.0/24) RDS Aurora Primary (Writer) RDS Aurora Replica (Reader) Async Replication Legend Public Subnet Private Subnet DB Subnet Sync Traffic Async / Data Flow 3-Tier VPC Architecture — Generated by architecture-diagram-agent