Ours looks like this:
<caching>
<profiles>
<add extension=".css" policy="CacheUntilChange" kernelCachePolicy="DontCache" />
<add extension=".gif" policy="CacheUntilChange" kernelCachePolicy="DontCache" />
<add extension=".jpg" policy="CacheUntilChange" kernelCachePolicy="DontCache" />
</profiles>
</caching>
I am wondering because our production website does not have this node, but our local dev web.config does.