see the announcement here (under the section titled "Improving Website Speed"). Please change your hosts file back immediately.
If the Content Delivery Network (CDN) is unable to contact the site, it will attempt to deliver a cached version of the pages if one is available.
If the site is inaccessable for more than a short blip, then we want to know details about it so that we can report it. Instructions for what we would like to know are below: