i have seen handlers and modules can be written to hook up in the life cycle of asp.net pipeline.
so when i noticed that response.redirect(~/Default.aspx) sends back
302 found to the browser and then browser executes GET for the url http://localhost:81/Default.aspx
then I realised that it is possible to put some path to in http://localhost;81/kkk/default.aspx
by intercepting the 302 found http://localhost:81/Default.aspx and changing it to http://localhost;81/kkk/default.aspx
so that when browser calls to should call the new one.