← Back to Glossary

What is a Load Balancer?

by Bethany Hendricks on Glossary • November 26, 2020

A load balancer is a network function or application service that distributes client traffic across a pool of backend/application servers.

Different load balancing algorithms can be employed to operate on the data available at the relevant OSI networking layer to facilitate decision-making around the distribution of client traffic. Common hashing algorithms used include round-robin, weighted least connections, and resource based, among others.

A load balancer monitors the backend servers they proxy by performing health checks to the specified network (layer 4) or application (layer 7) endpoints. A load balancer takes the health of backend servers into account when deciding what server to send client traffic to, in addition to other decision-making mechanisms such as hashing.

A load balancer can be provisioned as an appliance or, more recently, as a service using the Load Balancing as a Service model.