Hello, I'm using the WebDevHelper toolbar for Internet Explorer to troubleshoot HTTP requests/roundtrips on my SSL site and noticed that IE re-downloads my CSS :hover images every time they are triggered. This causes a huge amount of roundtrips.
How can I prevent this from happening?
Edit: All static content is served with cache-control: public, so images, javascript etc. are cached in Firefox and Chrome. This problem is IE specific.
Content served via SSL will not be cached for security reasons. If you want something to be cached, serve it via HTTP.
Have you tried adding to the header for those type of static files.
P3P: CP="CAO PSA OUR"
I know this works with in IE to allow storage of cookies through framesets and stuff. Not sure if it works with static files under HTTPS.
Serve static content via http, sure, but don't do separate images for :hover states. Proper css image sprites should be used. It's just good practice all around, via https or http. There are tons of resources available for creating sprites. Supposedly SpriteMe, [ http://spriteme.org/ ] is an attempt to automate css image sprite creation.
Well there are multiple issues according to other Stackoverflow posts. FireFox 2.x also has this problem. But FireFox 3.x doesn't.
http://stackoverflow.com/questions/174348/will-web-browsers-cache-content-over-https/174509#174509
Also in Internet Explorer, you go to Tools > Internet Options > Advanced tab > Security section > Do not save encrypted pages to disk. It appears to be unchecked by default in IE6, 7 and 8.
I know it sounds weird... try to put a url to something that isn't exists (404 error). after this, all the rest of the images will be cached.
If the images are being delivered from a different hostname than your main page, then you're hitting the artifact described here: http://blogs.msdn.com/ieinternals/archive/2010/04/21/Internet-Explorer-May-Bypass-Cache-for-Cross-Domain-HTTPS-Content.aspx