I wrote an asp.net application with default.aspx. When I hit this page It is asking me windows login popup window. My application should me windows authentication required b
You can't do much from the server-side. However, your clients (if they are members of your orgnaization for instance) can add your site to their Local Intranet security zone in IE.
Tools - Internet Options - Security - Local Intranet - Sites
Note this will probably only work for IE clients.
By default, IE automatically send current windows credentials to sites in the Local Intranet zone requesting for an authorization.
This way, they will not be prompted for their credentials each time they are accessing your site.