If your Apache website is under a load-balancer or proxy, some features might not work very well. The proxy, for example, might “hide” the true IP from clients, the address your application sees in REMOTE_ADDR attribute (PHP, for example) will be the IP of the proxy renders IP-ban in .htaccess useless.
If such things happen, time to do some configuration. First, you need to enable the mod_remoteip module to handle requests through a proxy. It will allow you to “rewrite” some headers in the request to make your web application to know the true client IP.