How does one detect a browser’s cache settings (on/off)

How does one detect a browser’s cache settings either client side or server side (ASP.NET). Basically trying detect if the users browser has caching on or 开发者_Python百科off. If it's off, I'd like to either redirect them to a page with error message to tell them to turn it on. Is this possible?

You can't reliably detect cache settings as this information is not passed on from the browser.

If resources that should be cached are being requested repeatedly from the browser, this may be an indication that caching is turned off, but that might not be the case.

As for wanting to redirect to an error page - some browsers and environments simply do not have caching, do you want to penalize these users?

Caching is a mechanism to reduce load by reducing the number of requests, don't use it for anything else.

A browser doesn't send out its cache setting to the server.

Maybe you are trying to make some of your page components (images, scripts, etc.) load / interact smoother? If it is, maybe you could try to optimize your page (e.g. sprite, minimized JavaScript) so you don't have to worry too much whether the browser decides to cache your page.

Also, in general, rather than redirecting to a different page, you might also consider simply showing a message on the same page (i.e. 1 less HTTP request).