Application Load Balancer (ALB) operates at Layer and understands HTTP/HTTPS.
Routing rules:
- Path-based: /api/* to API servers
- Host-based: api.example.com routes differently
- Header-based: Route by headers or cookies
Target types:
- Instance: Route to EC instances
- IP: Route to specific addresses
- Lambda: Invoke serverless functions
Features:
- WebSocket support
- HTTP/
- Authentication integration
- WAF integration
Use ALB when:
- You need content-based routing
- Application uses HTTP/HTTPS
- You want built-in authentication