How to set up 404?

Question

Apache HTTP Server

The fact is that there are a bunch of sites on the host and for all there is a single htaccess in which there is a path to each of the sites, so we need to definitely call it example.com so that if it issues 404, 404.php opens

Answer 1

ErrorDocument 404 /404.php

....образно
ErrorDocument 400 /404.php
ErrorDocument 401 /404.php
ErrorDocument 403 /404.php
ErrorDocument 404 /404.php
ErrorDocument 500 /404.php