Socket app with Domain name

Dear All,
I created a socket server application for receving data from GPS tracking device through the port number ****.It is working based on the IP address.Here everything working perfect.
Now Instead of IP address need to create a socket application for receing data from GPS tracking device through the domain name.How can I create that without using Ip address. I created a domain name test.testing.com and unit also configered with domain name. But hpw can I start my work. Any Ideas are most welome