How to specify HTTP expiration header? (ASP.NET MVC+IIS)

Question

I am already using output caching in my ASP.NET MVC application.

Page speed tells me to specify HTTP cache expiration for css and images in the response header.

Answer 1

Found it:

I need to specify client cache for static content (in web.config).

from http://www.iis.net/ConfigReference/system.webServer/staticContent/clientCache