Yep. They give you a little program that runs on your computer that checks your external IP address at frequent intervals and updates the DNS records when it changes. Better yet, some home routers have a configuration page where you can select among popular Dynamic DNS providers and then you don't need to run the proprietary program. My ISP-provided router (FiOS) has ZoneEdit in the list which I've used for years even before I had FiOS, so it was a nice surprise when I found it there. Just for sake of example here's a link: http://www.zoneedit.com/dynamicDNS.html