What is the default cache refresh time of InternetOpenURL?

Question

One of my programs uses InternetOpenURL without the INTERNET_FLAG_RELOAD specified. I see that the call will read the web page from the cache (if it exists). I changed the web page 5 days ago and I still get the cached version (unless I specify the flag above.) Does anyone know when or if the cache will ever be updated? I'd expect it to eventually be refreshed (possibly overly optimistic!)

Answer 1

Chances are the original resource had an expiration date on it that is more than 5 days, that is why the cached version keeps being used if you do not tell InternetOpenURL() to re-check the server once in awhile. However, INTERNET_FLAG_RELOAD forces it to re-download the resource whether it has actually been modified or not. That might be a little too brute force for your needs. Try using INTERNET_FLAG_RESYNCHRONIZE instead. That allows InternetOpenURL() to check if the resource has been modified and then re-download it only if needed, otherwise keep using the cached copy.