title: How to specify HTTP expiration header? (ASP.NET MVC+IIS)
body: <p>I am already using output caching in my ASP.NET MVC application.</p>
  
  <p><a href="http://code.google.com/speed/page-speed/" rel="noreferrer">Page speed</a> tells me to specify HTTP cache expiration for css and images in the response header.</p>
  
  <p>I know that the Response object contains some properties that control cache expiration. I know that these properties can be used to control HTTP caching for response that I am <b>serving from my code:</b></p>
  
  <pre><code>Response.Expires
  Response.ExpiresAbsolute
  Response.CacheControl
  </code></pre>
  
  <p>or alternatively</p>
  
  <pre><code>Response.AddHeader("Expires", "Thu, 01 Dec 1994 16:00:00 GMT");
  </code></pre>
  
  <p>The question is <b>how do I set the Expires header for resources that are served automatically, e.g. images, css and such?</b></p>