Apache, as you know, is the most popular web server in use today. Since it is historically easily installed, easily configured and very flexible, it’s not difficult to see why.  Many of the easily configured options that are possible with Apache, however, are not exploited to their fullest.  Most of Apache's various server configuration options are switched off by default, and although this makes the server much more secure, it also means that a default installation will not take advantage of many of the things that make Apache what it is.  The httpd.conf file, Apache’s main configuration file, actually says in section 2: "Note that from this point forward you must specifically allow particular features to be enabled…"

Error messages are certainly a pertinent example of this; Apache can very quickly and easily be set to display almost anything you want, from simple text (yuk) to custom HTML pages or even PHP and Perl scripts.  It’s all too common, however, to see the very plain, default error messages that are displayed when the server encounters the standard set of errors, such as the all too familiar 404 or "Page not found" error response.  These default pages are ugly, sometimes confusing, very often nothing like the rest of site and almost always detrimental to user experience.  There’s no excuse for sticking with these default error pages, especially when it really is so very easy to use alternatives of your own devising.

Anyone reading this is going to be using Apache, if not in production, then at the very least as a development tool, but the browser you use for testing can also have an impact on your work.  With the default set up of Apache, if you use Mozilla to try to access a page that does not exist you will see the default Apache server 404 error page, but if you use MS IE5+ you won’t see the default Apache 404. Instead, you’ll see the default Internet Explorer 404 page.  This is Microsoft’s so called "friendly error message" which overrides the Apache defaults.  The reason for this is that the Apache defaults are all less than 512 bytes. 

This overriding featuring of IE can be switched off using the "show friendly error messages" setting in the Tools -> Internet options dialogue, although by default it is set to on, so bear in mind that most people will have this set if they are using IE (which a large number of Internet users are).  This isn’t overly important but should be taken into consideration; to overcome this setting automatically, you need to ensure that the pages you wish to use as error pages are larger than 512 bytes.  This isn’t too difficult to achieve, but if you aren’t seeing what you should be seeing when creating and testing your error documents, it would be wise to check the file size of your error pages or disable this feature in IE.