HI @Venkat
You can use a third party browser plugin to find the ASP.NET version.
Plugin
http://builtwith.com/toolbar
This plugin is available for most of the popular browsers like Firefox, Chrome and Safari except IE, when I write this post. Just include this on your browsers, and you can find out the technology behind with the currently rendered on the browser.
Sample Image
Using Developer Toolbar:
IE doesn’t require any plugins or add-ons. You can find the technology behind this using the built-in tool called “IE Developer Toolbar”. This toolbar, contains a tab called “Network”. In this tab, you can find the necessary details.