Enabling Expires Header on IIS7

Open up IIS Manager,

1. Locate the folder where files (e.g. js, css and images) are located and needed to be configured with Expires Headers.

2. Click on HTTP Response Headers

3. Under Action page, click Set Common Headers

4. By default, "Enable Http keep-alive" is checked. Leave this as it is.

5. Another tickbox "Expire Web content", ensure this is checked. You can set the expires as long as required.