Deleting CAPTCHA GIF From IE Cache

[Alec Lee]

I have come across a site (actually an online web based game) that presents a CAPTCHA gif to defeat automation script. The point is I found that the site is also able to prevent people from retrieving the CAPTCHA gif from the IE 7 browser cache (in C:\Documents and Settings\username\Local Settings\Temporary Internet Files) by not storing the related gif there.

My question is how is it possible to prevent IE from storing a GIF in the browser cache programmatically. I have removed all unrelated files in the cache and is sure that it is not adding anything new files to the cache when loading the CAPTCHA.

[Eric Pascarello]

Set up the serverside to add non caching headers to the image when server
or
Give the image an unique name [set random querystring value or actually name it different.]

Eric