Controlling cache of web files that should be cached already

Question

I'm using Fiddler2 to see page load times. There are lots of jpg,gif,png,etc. listed. Most return code 304 which I believe means that the browser does not have to download that again. It seems that even though it does not download again, there is overhead in the checking. I have 33 such objects and round trip just to check is close to 40K ! ? Is there a method that keeps the browser from even checking in order to save the 40K and time needed? I am using asp.net, but this seems like a generic question for html. As a follow up how to control the cache time of simple CSS files.

Thanks, Ron

Answer 1

It has nothing to do with HTML; it has to do with HTTP. Read up on the Cache-Control headers, which instruct the browser (and any intermediary caches) how long to cache something, and when/whether it should check for a more recent version.