url to local host and windows authentication

I'm developing an intranet site for a client on my development system.  I'm using windows authentication and I understand I should not be challenged to logon when I open the Intranet Site.  However I am.  I was speaking to a tech from microsoft, and he said it was because the url I'm using goes out to the internet.
http://localhost/IntranetSiteName/Default.aspx 
How should I change the URL so it opens the IntranetSite on my local pc?
 
THanks for your help.
 
 
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