Apache allows you to customize the server at the directory level, using .htaccess files. This tutorial explains how to use them to serve custom 404 error (page not found), and other common error pages, to your users.
Server response codes
A server reponse code is a three digit number sent by a server to a user in response to a request for a web page or document. They tell the user whether the request can be completed, or if the server needs more information, or if the server cannot complete the request. Usually, these codes are sent ‘silently’ – so you never see them, as a user – however, there are some common ones that you may wish to set up error pages for, and they are listed below. Most people will only ever need to set up error pages for server codes 400, 401, 403, 404 and 500, and you would be wise to always have an error document for 404 errors at the very least.
It is also relatively important to ensure that any error page is over 512 bytes in size. Internet Explorer 5, when sent an error page of less than 512 bytes, will display its own default error document instead of your one. Feel free to use padding if this is an issue – personally, I’m not going to increase the size of a page because Internet Explorer 5 doesn’t behave well.
In order to set up an error page for any other error codes, you simply add more lines to your .htaccess file. If you wanted to have error pages for the above five errors, your .htaccess file might look something like this:
ErrorDocument 400 /400.html
ErrorDocument 401 /401.html
ErrorDocument 403 /403.html
ErrorDocument 404 /404.html
ErrorDocument 500 /500.html
Informational
100 – Continue
101 – Switching Protocols
Successful
200 – OK
201 – Created
202 – Accepted
203 – Non-Authoritative Information
204 – No Content
205 – Reset Content
206 – Partial Content
Redirection
300 – Multiple Choices
301 – Moved Permanently
302 – Found
303 – See Other
304 – Not Modified
305 – Use Proxy
307 – Temporary Redirect
Client Error
400 – Bad Request
401 – Unauthorized
402 – Payment Required
403 – Forbidden
404 – Not Found
405 – Method Not Allowed
406 – Not Acceptable
407 – Proxy Authentication Required
408 – Request Timeout
409 – Conflict
410 – Gone
411 – Length Required
412 – Precondition Failed
413 – Request Entity Too Large
414 – Request-URI Too Long
415 – Unsupported Media Type
416 – Requested Range Not Satisfiable
417 – Expectation Failed
Server Error
500 – Internal Server Error
501 – Not Implemented
502 – Bad Gateway
503 – Service Unavailable
504 – Gateway Timeout
505 – HTTP Version Not Supported