Unless there is intentional exchange between Classic ASP site and NET application** even running on the same site(!!!) but separate app pools for obvious reason, for example using application variable for storing values, there is no way that Classic asp would pass variable to NET application. Even session variable is not shared between Classic ASP and NET. It has to be done intentionally in code.
For example if you using iframe and passing variable in url string from NET app to classic ASP page or back or just calling NET app from classic ASP page and passing variables in URL string or verse versus.
** Or using cookies to share values between application if you running under same domain.