Automatically update Windows 8 hosts file when creating subdomains with WordPress multisite

So I have set up WordPress Multisite locally to test etc. I have set it up so new sites are on subdomains. When I create a new subdomain I will have to manually create a new entry in the hosts file. Is there any way to do this automatically when the new subdomain is created?

Also, when I put this site live, will I be able to get the server to do this automatically? Similar to how when you create a new subdomain on WordPress.com? I'm sure they don't have a team of people manually updating the DNS records everytime someone creates a new WordPress blog.