Determine ASP.NET root page
Sometimes when an ASP.NET page loads up from the root of a directory, the page name is not revealed via HTTP headers. If it’s a webforms application, simply scroll down the Postback form section. (id=”aspnetForm”)
Look at the action attribute. See the sample below.
<form name="aspnetForm" method="post" action="Home.aspx" id="aspnetForm">