How to configure web servers to specify document modes in .net ?

The X-UA-Compatible header allows web developers to specify the document modes supported by a webpage.
Here we learn how site administrators can configure their web servers to serve sites so that they default
to a specific document compatibility mode by defining a custom header for the site.
For example, the following web.config file enables Microsoft Internet Information Services (IIS) to define
a custom header that automatically renders all pages in standards mode.

<?xml version="1.0" encoding="utf-8"?>
        <clear />
        <add name="X-UA-Compatible" value="IE=9" />

If you add this meta tag to the head of your master page then it will force IE to use the latest version:-

<meta http-equiv="X-UA-Compatible" content="IE=edge" />  

If you want to force IE to use an older browser for example IE7, then use:-

< meta http-equiv="X-UA-Compatible" content="IE=7" />

Document modes specified through a web server have a lower precedence than document modes specified in a webpage.
Means, if your server specifies IE9 Standards mode for a given webpage, but the page contains a meta element that specifies
IE8 Standards mode, the webpage will be displayed in IE8 mode by versions of Internet Explorer that support that
document mode.