it can be very tricky if you are using godaddy like shared hosting. and at the same time if you are trying to use asp.net ajax toolkit.
at the end you will find yourself why the hell ajax part does not work. its all about urlrewriting and its file issues. you need to put to zero size file to your application folder.
ScriptResource.axd
WebResource.axd
it will solve urlrewriting and ajax problems. I hope someone make some enhancements to urlrewriting project.