A dynamic ip address is assigned to your router everytime it turns on - even sometimes if it has been unused for a while - that means the address mapped to your network changes all the time. That is bad news if you are running a radio station - it's like your call letters and number change all the time - confusing.
Luckily there's an app for that - several companies have created a free service that will basically monitor your home ip address and update their DNS records with that information. You can use your own domain name "mystreamingradio.com" or one of theirs "reggae.servemp3.com" to give out to your listeners and all of that mapping is handled in the background by the 'dns heartbeat' application installed on your radio station box.
So let's go ahead and get that set-up: