ELB difference for load balancing t-shirt

Core Purpose & Functionality

ELB automatically distributes incoming application traffic across multiple targets—such as Amazon EC2 instances, containers, IP addresses, and Lambda functions—across multiple Availability Zones. By acting as the single point of contact for clients, ELB ensures your applications can handle varying loads without disruption, prevents server overloads, and enhances overall fault tolerance.

Key Types of ELBs

AWS offers different load balancers tailored to specific traffic routing needs:

• Application Load Balancer (ALB): Best suited for HTTP and HTTPS traffic. It operates at the request level (Layer 7), enabling advanced routing based on path, host, headers, or query parameters, making it ideal for modern microservices and containerized architectures.

• Network Load Balancer (NLB): Operates at the connection level (Layer 4) to handle high-throughput, ultra-low-latency TCP, UDP, and TLS traffic. It is designed to handle millions of requests per second while maintaining extreme performance.

• Gateway Load Balancer (GWLB): Makes it easy to deploy, scale, and manage third-party virtual appliances (such as firewalls, intrusion detection systems, and deep packet inspection systems) in the cloud.

• Classic Load Balancer (CLB): A legacy load balancer that routes traffic across multiple EC2 instances based either on IP address or port (Layer 4 and Layer 7). AWS generally recommends using ALB or NLB for newer applications.

Key Benefits

• High Availability & Fault Tolerance: Automatically detects unhealthy targets and routes traffic only to healthy ones, seamlessly redistributing loads if an Availability Zone fails.

• Scalability: Automatically scales its handling capacity up or down smoothly in response to incoming traffic spikes without manual intervention.

• Security & Compliance: Integrates tightly with AWS Certificate Manager (ACM) for SSL/TLS offloading, supports advanced security policies, and works alongside AWS WAF (Web Application Firewall) to protect web apps from common exploits.