loadbalancing

Load balancing is the process of distributing client requests or network traffic across multiple servers or resources to optimize resource use, maximize throughput, reduce latency, and ensure fault tolerance. A typical load balancing setup includes a load balancer, a pool of back-end servers, and health checks that monitor server availability. The load balancer forwards traffic only to healthy servers and can automatically redirect traffic when a server fails. Load balancing can be implemented as hardware appliances, software solutions, or managed services, and is commonly deployed in front of applications, databases, or services.

Load balancers operate at different layers. Layer 4 load balancers route traffic based on transport-layer information such as IP address and port. Layer 7 load balancers inspect application-layer data (for example HTTP headers and URLs) to make routing decisions, enabling features such as content-based routing and TLS termination.

Common load-balancing algorithms include round-robin, least connections, and weighted variants, as well as IP-hash. Some support session persistence (sticky sessions) to bind a user to a specific backend for the duration of a session. Health checks verify that back-end servers respond correctly.

Deployment models vary: hardware devices, software on standard servers, or cloud-native services. DNS-based load balancing and Anycast provide global distribution, while in-container or orchestrated environments use ingress controllers or service meshes to manage traffic to microservices.

Practices include autoscaling, health-driven failover, SSL/TLS offloading, and security features such as DDoS protection and Web Application Firewall integration. Monitoring latency, error rates, and backend health is essential for maintaining performance.