Unfortunately our monitoring bot(s) do not work exactly like a web browser does. So they are unable to accept cookies. As such some web pages that require cookies, or try to set them and then perform a re-direct, may not be monitored correctly. For example, your web server may return a 301 Redirect or 302 Found status code (both of which we consider as up.)
However if you use our page content monitoring feature it will not work with a re-direct such as this. If you have any questions please contact support@siteuptime.com and we can let you know if it will work for your web page or not.