Files that the browser retrieves from the server should be stored in the browser’s cache as long as possible to help minimize server round-trips.
But how does IIS knows what is actually a static content and what is not?
Is it just images , css , js and not ASPX , ashx...?
Where can I see in the IIS what is already considered to be static and what not ?
And what about the scneraio where a page has been declared with
<%@ OutputCacheheader(withoutlocation) . does the images,css,js src files inside of it , are also being output cached ?As a best prcatice , I should set one year into the future as the maximum expiration time.I should use that as the default for all static content on the site
So I did this :

But later , after pressing OK , I can't find any summary menu which shows me : to whom I already put a response header(in this case : the css folder).
Currently , in order to see that css folder has been applied with respose headers - I have to go to the css folder again --> Http Response Header-->Set Common Headers--> and then I see it. It doesn't written in the web.config.
But if I do it for a file (Login.aspxfor example): I do see it in web.config :
<configuration>
<location path="Login.aspx">
<system.webServer>
<staticContent>
<clientCache cacheControlMode="UseExpires" cacheControlMaxAge="1.00:00:00" httpExpires="Fri, 15 Feb 2013 00:00:00 GMT" />
</staticContent>
</system.webServer>
</location>
</configuration>
