Recently I was working on a site that NEEDED to be internet facing during development. VPNs, Firewalls, Corporate overlords. You get the gist..
Anyway… if you even end up in a situation like that, just jump into IIS -> Select the site in question -> Click “Http response” and add a custom HTTP Response header to tell the Robots they’re not welcome .
Always remember it’s a “Suggestion” not a “Rule” and the Major Search engines will usually comply and not Index your site. HOWEVER .. the little robots around the internet may not be so nice so I would still suggest not pasting your dev site in public forums etc.