Galin Iliev's blog

Caching is popular technique for reducing network traffic and server recourses when it comes to web content. But how we can cache static content like .jpg, gif, .js files?! 

Seems easy: just start IIS Manager... and ... Wait! there is no icon for it there! Hmm

it's not so easy though... but possible:

just follow these steps:

1. Allow overriding static content setting:

open %systemroot%\System32\inetsrv\config\applicationHost.config
search for <section name="staticContent" overrideModeDefault="Deny" />

change it to <section name="staticContent" overrideModeDefault="Allow" />

2. set cache settings using following commands (from IIS.NET forums)

set max-age to 1hr for all static files under /images on default-web-site, run the following

\Windows\system32\inetsrv\appcmd.exe set config "Default Web Site/images" -section:system.webServer/staticContent -clientCache.cacheControlMode:UseMaxAge

\Windows\system32\inetsrv\appcmd.exe set config "Default Web Site/images" -section:system.webServer/staticContent -clientCache.cacheControlMaxAge:"01:00:00"

If you give it a shot now you will see that the content is cached! Not believe?! Try to request image from the browser, overwrite the image with image with same name and different content and request image from the browser again...

But the bad news is that caching is on the server - so you haven't reduced network traffic as web server is still hit.

3. Cache it on client

open %systemroot%\System32\inetsrv\config\applicationHost.config

and change the lines like this

<location path="MyWebsite"> 

    <system.webServer> 

        <caching> 

            <profiles> 

                <add extension=".html" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".htm" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".gif" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".js" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".css" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".jpg" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".jpeg" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".zip" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

                <add extension=".rar" policy="CacheUntilChange" kernelCachePolicy="DontCache" location="Client" /> 

            </profiles> 

        </caching> 

    </system.webServer> 

</location>

So it is done :)

Thanks to Aaron Murray