I have a ASP.NET website in windows azure that uses a web reference. I use azure as my QA environment and on QA, the site should connect to the QA web reference. On my previous QA environment, I used hosts file entry to point the web reference domain name to the QA IP address. but after migrating to windows azure, I don't know how to point the web reference to the QA IP address. is there any other way to do it?
I do not believe you can affect hosts in Azure.
Instead, I suggest using SlowCheetah. It is an open source project that will transform your configuration file (or any XML file) based on the build you are targeting. I use it to change the connection string in web.config for QA and PROD builds.
This package enables you to transform your app.config or any other XML file based on the build configuration. It also adds additional tooling to help you create XML transforms.
https://visualstudiogallery.msdn.microsoft.com/69023d00-a4f9-4a34-a6cd-7e854ba318b5
You can set your web reference to be dynamic, so that the specifics are loaded from your web.config. See