For an external load balancer to effectively distribute traffic to a backend service, defining health checks is a crucial configuration. Health checks are mechanisms that allow the load balancer to determine the availability and performance of the backend instances. When health checks are defined, the load balancer can regularly ping the backend services according to a specified interval, and based on the responses, it can decide whether to route traffic to those instances.
If a backend service fails health checks, the load balancer will stop routing traffic to it, ensuring that users are not directed to services that are down or experiencing issues. This helps maintain high availability and reliability for applications using the load balancer. Therefore, defining health checks is essential for operational efficiency, as it enables proactive traffic management and minimizes downtime.
Other configurations, such as adding custom domains or setting up user authentication, while important in different contexts, do not directly relate to the core functionality of the load balancer in managing backend service health and availability. Creating documentation is also valuable for operational clarity but is not a technical configuration necessary for the load balancer's functionality.