As per your question i think you know how to develop a web site using asp.net for internet..
am i right or right....?
so if you know how to do this.. so you have to develop your application in the same mannar and then when it is completed and after you get build that application then you need to follow this procedure....
1) Create a Virtual directory in IIS and put your website in that directory...
2) and in intranet you can access that site using your server's ip address
means the IP address of your machine where your website is hosted in IIS..
this is some example for IIS hosting..
http://www.startvbdotnet.com/aspsite/extras/deploy2.aspx[
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http://www.sevenforums.com/tutorials/23733-host-website-iis7-5-a.html[
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