Varying the Output Cache by Header
Use the VaryByHeader to create new cached versions of a page in case of new browser header changes.
Several standard browser headers are transmitted with each page request, including
Accept-Language: a list of languages.
User-Agent: type of device making the request.
Cookie: the browser cookies created in the current domain.
<%@ Page Language="C#" %>
<%@ OutputCache Duration="3600" VaryByParam="none" VaryByHeader="User-Agent" %>
Vary By Header