IIS works on localhost but not from outside/via IP

I have 2nd deployed ASP.NET MVC on IIS 8.5 (Windows Server 2012 R2). When I bind it to 80 port, it works fine as 'localhost' but when I assign a HostName [www.example.com ] or IP address to access externally, I can no longer access the site. its redirected to hostname/Maintenance

this is the screenshot of localhost

rks