Proxy Server Newbie Question

can it be configured to not cache some pages?

[Mr Bo Jangles]

I know nothing about these servers except that they can upset my web application when a client has one installed because they serve pages to users when I really want the request to go back to the remote main web server.

Question is, when you configure a proxy server (are these also sometimes called a caching server? or is that some other animal?) is it possible in the server config to specify certain URLs (or whole domains) that should NOT be cached? That would solve my problems.

Thanks,

[MattyMoose]

are these also sometimes called a caching server? or is that some other animal?

Well, a proxy server doesn't necessarily need to be a caching server, but a caching server needs to be a proxy server, if you get my meaning. I used to run MS Proxy Server 4.0 way back when on my old gateway, and it had a 1GB hard-drive. Not exactly oodles of space for cache, so all it did was proxy, no cache.

At any rate, to answer your question, yes, I'm sure that you could set it so that the proxy doesn't cache certain domains, or IPs, etc, but you would have to do this for every client that has a proxy server which connects to you. An easier way to go about it may be to add "No-Cache" HTML metatags to your site.

The two recommended are:
<META HTTP-EQUIV="PRAGMA" CONTENT="NO-CACHE">
<META HTTP-EQUIV="CACHE-CONTROL" CONTENT="NO-CACHE">

The first line is HTTP/1.0 compatible. This *should* prevent the caching servers from caching your site, but, there are settings in programs such as squid to ignore no-cache headers, and cache it anyway. Most people will not turn this on, only people on extremely bad links in remote places will often do that. (Or they just don't care about updated content).

HTH,
-MM

[Mr Bo Jangles]

thank you Matty

[py9jmas]

Intermediate caching proxy servers ignore the contents of HTML pages - they don't have the time to parse HTML looking for meta tags. They do honour HTTP headers.

See [mnot.net...] for more info.

Also, Pragma: is undefined for HTTP server replies to clients. It is only defined for use by clients in their requests.

[Mr Bo Jangles]

excellent ref thanks py9jmas