Facebook Channel File in ASP.NET

channel file is optional but recommended, channel file is used to address certain cross domain communication issues(from your domain to facebook.com) in some browsers, you can use channel.aspx as long as it returns the content described by the API. Caching the channel file is recommended for web applications, read this to know how asp.net handles caching : http://msdn.microsoft.com/enus/library/xsbfdd8c(v=vs.71).aspx

and read the "channel file" topic in the link you described to know more.