If you are running an internal server linked to a domain name, you won’t be able to access the server using that domain name from internal network.

For example, if http://www.server.com points to the apache server running on your computer, you have to edit the Windows host file if you want to access your server by using http://www.server.com

Simpley, go to C:\Windows\System32\drivers\etc and edit the hosts file.
Add the mapping by specifying an IP and a domain name.
e.g. http://www.server.com

You must restart the computer for it to take effect.