ingress-nginx/docs/user-guide/default-backend.md

Default backend

The default backend is a service which handles all URL paths and hosts the nginx controller doesn't understand (i.e., all the requests that are not mapped with an Ingress).

Basically a default backend exposes two URLs:

• /healthz that returns 200
• / that returns 404

!!! example The sub-directory /images/custom-error-pages provides an additional service for the purpose of customizing the error pages served via the default backend.