on page 3 of that howto you have: what if I don't have example.com registered to me? I just want this to be a lan only setup, can I just say server1 for that part?
Yes, you can name it just server 1, but make sure that the hostname you entered during ubuntu setup is the same then the hostname you enterd here and it must be the same in your smb.conf file later! Otherwise you might get login errors.
