For AI agents: The documentation index is at https://docs.digitalocean.com/llms.txt. Markdown versions of pages use the same URL with index.html.md in place of the HTML page (for example, append index.html.md to the directory path instead of opening the HTML document).

DigitalOcean Load Balancers periodically check the health of their target backend Droplets or DOKS nodes to ensure connections are routed only to healthy servers.

The backend service must be accessible and its health checks must be running to be in a Healthy state. A backend that fails the configured health checks is marked as Down in the control panel.

Check the following items to troubleshoot failing load balancer health checks:

• Check that your backend server software is functioning properly and not frozen, disabled, or otherwise not responding.
• Ensure any firewall running on the backend allows traffic on the correct ports and protocols.
• Avoid using software such as Fail2Ban which may errantly block the load balancer IP instead of the original client IP.
• If using Cloud Firewalls, make sure that the load balancer is added as a source in the appropriate firewall rules.
• Ensure your server software is listening on the private network interface. All load balancer traffic goes through the specified private VPC network.
• If using the PROXY protocol, make sure your health check endpoint (the URL specified in the Path setting of the health check) also accepts PROXY protocol.
• If using HTTP or HTTPS for your health check endpoint, make sure you return an HTTP status code indicating success in the 200–299 range.

Related Topics