perhaps I explained badly...
I installed forum on a local network PC (address: 192.168.2.33) and by typing this address in web browser you are entering this forum, but I want to change IP address with name (f.e. forum.com, this address already exists). So I thought, is it possible to drop request for "real" forum.com and redirect this request to 192.168.2.33 so by typing in web browser
www.forum.com I could enter my forum which is in a local network (192.168.2.33).