If you want the load balancing setup to increase the reliability of your application, you need to setup a health monitoring procedure. The main task of the load balancer is to distribute the incoming requests to one of the underlying nodes. To ensure that a given node is available and the application on it is responsive, you must configure a health monitoring procedure. Usually, this is a configuration of the load balancer. It instructs the balancer to periodically issue a request to a specific page of every application on every node and validate the response. We recommend that you create a custom status page with a very specific content, which will be verified by the load balancer, instead of relying on the status code of the response. Not depending on the status code is a good way to avoid false healthy responses from a server that has custom error pages returning an OK status code. To prevent easy DoS attacks, we recommend that the status page should be invisible for external to the load balancer requests.
The configurations for such health monitoring are specific to each software or hardware load balancer. You must check if your load balancer supports such configuration.