How to set cache expiry date

Trying to cache a large js file on the client browser. When I check firefox's cache information, it shows the js to expire on 12/31/1969. I'm using IIS6 and have tried adding the following code to the web.config:

  <staticContent>
     <clientCache cacheControlMode="U开发者_如何学运维seMaxAge" cacheControlMaxAge="30.00:00:00" />
  </staticContent>

Still the same. How can I get the browser to cache this file?

In IIS, right click on your Site node and click Properties. Go to the HTTP Headers tab, tick Enable content expiration and set an expiry time.

You may have to configure that in IIS, I'm not sure that IIS6 honors that web.config setting like IIS7 does.