Small Business Server 2003 – External DNS name

I have built a second server to replace my aging small business server 2003. Internally it works fine, exchange server works fine but I have an external name for my server so I can access it through Remote Desktop Connection. When I attempt to access the new server (removed old one from router, pointed all incoming ports to new server’s IP address) I can not access the server with the old external name. Reset router pointers and hooked up the old server and all works again. I need to get this done quickly as my hard drive in the old server is dying. My externalname is mail2.nccincci.com, which also is how I can use OWA for web mail. Where do I look?