Elastic Load Balancing (ELB)

What it is: A service that distributes incoming traffic across multiple targets (instances, IPs, containers).

What it’s for:

• High availability and better performance.
• Health checks and automatic routing away from unhealthy targets.

Key ideas:

• Main types:
  • ALB (Layer 7 HTTP/HTTPS)
  • NLB (Layer 4 TCP/UDP)
• Integrates with ASG for scaling.

Exam cues:

• “distribute traffic to multiple EC2 instances” → ELB.
• “route based on URL path / host header” → ALB.

Hard words:

• *distribute* /dɪˈstrɪbjuːt/: phân phối
• *target* /ˈtɑːrɡɪt/: đích nhận traffic
• *health check* /helθ tʃek/: kiểm tra sống