Thanks for answering.
Searching the net I have read in Microsoft:
The
Expires
,
ExpiresAbsolute and
CacheControl properties have been deprecated in favor of the methods of the
HttpCachePolicy class available through the
Cache intrinsic object to control the Internet Information Services (IIS) output cache and client caches.
It is that I am doing tests with AspJpeg from Persits and I have created an asp page that changes the size of the image by means of a string (ej,. image.asp?width=230&file=myphoto.jpg) and for that reason I have to put the cache in the page, because I don't know if assigning a cache to a jpg via web.config will also do it to the results of this page.