Hello Linux Apache gurus, I have been running a public Linux box for about 4 years. Until recently, I have not had much problems with the Apache web server or any of its configuration. Now, when I try to make a change to a website index.html file running on the Linux box server the change is not reflected when the website is requested in my favorite browser. Some weeks ago I had the same problem on another website on the same Linux box and after some time had passed the edited changes in the index.html were reflected when the website in question was requested in my favorite browser. Please advise, David.

As a rule, browsers and webservers tend to cache a page for as long as possible.
To force a reload, use Shift-Reload in your browser. This forces it to go to the server for the page. If the server doesn't reload from disk, you'll have to bounce Apache.
(Apologies if you know this already).

In theory, apache will return the file modification date along with the headers when requested by a proxy cache; the proxy should do this on every request of the page and serve up the cached page only if it isn't out of date.

Unfortunatly, many proxies are buggy in the respect, including ones built into some web browsers. For these, you need to flush the file out of the cache (usually purging the entire cache in the process) to get the page to load. Otherwise, the new page will work itself through eventually, usually taking about a month or so.