Vary Header being set by default on all requests

Hi Demis,

we are having some problems with cache invalidation in Internet Explorer.

The Vary header being set on GlobalResponseHeaders makes IE make a request to find out if the file has been modified since the last version it had cached.

Could you clarify why is this header being set by default for all requests?

Thanks in advance

It tells the browser that the same url can send back different content types based on the Accept HTTP Request Header, e.g. to prevent it returning a JSON response when a XML version of the service is called.