Day-24: Load Balancers (ELB, ALB, NLB)

🔹 What is Load Balancing?

Load balancing distributes incoming traffic across multiple servers to ensure high availability, scalability, and fault tolerance.

🔹 Types of AWS Load Balancers

AWS offers Elastic Load Balancing (ELB), which includes three main types:

1. Application Load Balancer (ALB)

• Layer: Operates at Layer 7 (Application Layer) of the OSI model.
• Protocol Support: Works with HTTP and HTTPS traffic.
• Use Case: Ideal for web applications, microservices, or containerized apps (ECS/EKS).
• Features:
  • Path-based and host-based routing.
  • Supports WebSocket and HTTP/2.
  • Integrates with AWS WAF (Web Application Firewall).
• Elastic IP: ❌ Not supported (ALB gets a DNS name, not a static IP).

2. Network Load Balancer (NLB)

• Layer: Operates at Layer 4 (Transport Layer).
• Protocol Support: Handles TCP, UDP, and TLS traffic.
• Use Case: Best for high-performance, low-latency applications.
• Features:
  • Handles millions of requests per second.
  • Preserves the source IP address.
  • Supports static IPs and Elastic IP allocation ✅ (you can assign an Elastic IP per AZ).
• Elastic IP: ✅ Supported — can attach Elastic IPs to NLB for static access.