Dynamic DNS with Bind
I work with a number of clients who have dynamic (or rolling) IPs assigned from their bandwidth provider. Since many of my clients require remote help, this can be a problem. However, many clients choose not to pay more for static IPs.
That’s why I chose to setup a zone in my domain name server for dynamic records. This means that when a triggering event occurs, the entry associated to a particular host record located inside the zone may be altered or changed as needed.
In my environment I am running a Bind DNS. While basics of Bind administration is required knowledge to complete setup of dynamic DNS, we will not cover that here. I will mention that you zone’s SOA times should be set short. I suggest 60 second intervals. I’ll also tell you that you will need the “nsupdate” command installed and working on the server that will actually process the update requests.
The next piece if the puzzle is a client to actually request updates. I created dynip for my clients. For my needs, a copy of the script can reside on my web server (which also happens to be my DNS). I can then password protect the script directory for security. You can easily employ DNS keys if your environment warrants (and most will).
When dynip is called, it grabs the IP of the client calling, compares it to the record on file and updates records as needed (if needed). So, if your IP has changed so does your DNS host entery. 
