{"head":{"title":"What Is a Load Balancer? Definition and Example | OceanLab","description":"A load balancer spreads incoming requests across several servers and skips any that are unhealthy. How it works, the main types, an example and mistakes.","canonical":"https://oceanlab.in/glossary/load-balancer"},"crumbs":[{"name":"Home","path":"/"},{"name":"Glossary","path":"/glossary"},{"name":"load balancer","path":"/glossary/load-balancer"}],"slug":"load-balancer","term":"Load balancer","aka":[],"category":"Hosting and delivery","short":"A service that spreads incoming traffic across several servers, and stops sending traffic to any that fail their health checks.","body":[["Users connect to the load balancer, not to a server. It picks a healthy server for each request, using rules such as round robin or least connections, and checks each server regularly. If one stops answering, traffic goes to the others."],["Some load balancers work at the network level and pass connections through. Others work at the HTTP level and can route by path or host name, handle HTTPS and add headers."]],"why":["A load balancer is what lets you run more than one server, which is the base for ",{"href":"/glossary/autoscaling","text":"autoscaling"},", zero-downtime releases and surviving a server failure. Without one, a single server is a single point of failure."],"example":["A school app gets a rush every morning when classes start. Behind a load balancer, three servers share the traffic. When one crashes during the rush, its health check fails and the other two carry on while it restarts."],"inBuild":["We put a managed load balancer in front of app servers from the first production deploy, give each service a real health check that tests its dependencies lightly, and use it to drain traffic before ",{"href":"/glossary/blue-green-deployment","text":"releases"},"."],"mistakes":[["Health checks that always pass, so broken servers still get traffic."],["Keeping user sessions in server memory, so users get logged out when they hit another server."],["A single load balancer in one zone, which moves the single point of failure rather than removing it."]],"related":[{"href":"/glossary/autoscaling","label":"Autoscaling","detail":"Automatically adding or removing computing capacity, such as servers or containers, as the load on a system goes up or down."},{"href":"/glossary/api-gateway","label":"API gateway","detail":"A single entry point that sits in front of a system's APIs and handles routing, auth and limits for every request."},{"href":"/glossary/blue-green-deployment","label":"Blue-green deployment","detail":"A release method that runs two identical production environments and switches all traffic from the old one to the new one in one step."},{"href":"/glossary/cdn","label":"CDN (content delivery network)","detail":"A network of servers around the world that keeps copies of your files close to users, so pages and media load faster."},{"href":"/glossary/kubernetes","label":"Kubernetes (K8s)","detail":"An open source platform that runs and manages containers across a group of machines: starting them, restarting them, scaling them and routing traffic to them."}],"tools":[],"links":[{"href":"/pricing/categories/cloud-hosting","label":"Cloud hosting pricing","detail":"Hosting prices side by side, with sources."},{"href":"/software","label":"Software by industry","detail":"Systems we build per industry, with guides and tools."}],"sources":[],"legal":false,"updatedAt":"2026-10-25"}