Assembly: System.Web (in system.web.dll)
The VaryByHeaders property identifies which request header parameters ASP.NET uses to uniquely identify a variation of the response when there are multiple cached responses for a resource. This is useful when a response depends on a set of client inputs, such as headers or parameters.
The HttpCacheVaryByHeaders is not directly related to HTTP cache-control headers, but helps ensure that a client or proxy varies by the specified headers. For more information about VaryByHeaders, see RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1, available on the World Wide Web Consortium (W3C) Web site. See section 14, "Header Field Definitions", for complete details.