How to setup Cisco Loopback

I have a cisco 1841 router with T1 setup and behind are couple of servers hosting my website abc.com and a few pc. I tried to browse my website abc.com from a pc and it goes no where. If I add DNS record abc.com to my internal DNS server and point it to the internal LAN server IP and it works. It there there anyway to setup the Cisco router to access loopback without adding an internal DNS record.

I also have a site forum.abc.com that’s hosted in the cloud and it uses forwarding URL. I cannot add forwarding in the internal DNS. Any help would greatly appreciated.