Internet Explorer: Strange behaviour of "Cache-Control: no-store, max-age=..."

Question

I'm currently facing some strange behaviour using the Internet Explorer (IE11 and all other "simulated versions" - IE8, IE9 and IE10 - in that IE11) when sending a Cache-Control header.

Our Web-Application is some kind of Web-Cam app showing live images using old school HTML4 (requirement). Those live images are sent using Cache-Control: no-store, max-age=10. So that image should be cache for about 10 seconds BUT NOT stored on the disk. This is important since its filling up the hard drive otherwise! Our customers use some very old hardware with very (and I mean very limited resources)!

Then there are other kind of images which should be cached for some time longer, lets say an hour. So I send the same header with Cache-Control: no-store, max-age=3600.

Problem

The problem is now: The first type of images (with 10 seconds max-age) are cached correctly. But, the other images are not cached at all. The browser requests the image a second time when it should use the cached one.

Any ideas?

Answer 1

After further testing I come to the conclusion that this is some caching limitation of IE (tested with REAL 9, 10 and 11).

From the above mentioned live image there is only shown one at a time. So the IE only needs to cache one instance of that image (with that specific name, lets say live_image.bmp).

From the other images (need to be cached for an hour) there are shown several (up to 32) at a time with the same image name but different URLs (they are distinguished by a time stamp and some other parameter).

Obviously IE does only cache five of that images and refuses to cache any other one.