App_Offline.htm file

Yesterday, we were testing something with our load balancer. Although we usually have a file that our load balancer would normally recognize to offline a site, it was not working. Since the site was a .NET 2.0 site (I think this would apply to 3.5 as well), I told our ops people about the App_Offline.htm file. Basically, this allows you to take a site offline and send users a friendly message. All you need to do is create this file and put it into the root of your website. The idea is that ASP.NET recognizes this file and shuts down the app-domain for any requests it gets and instead forwards requests to this static page. This is a helpful feature that not too many people know about.