Stuff you need for my solution which I'll explain and describe :
Your own domain name. For the rest of this document I will use the
canonical example domain example.com.
One nameserver on the Internet with a fixed IP which you have ssh access to.
I decided to make the "dynamic" name a subdomain of the domain name for two reasons:
The dynamic stuff wouldn't affect the main zonefile which would therefore be safe from updates.
The dynamic stuff could run with exactly one nameserver where the main domain name needs at least two to be accepted.
The nameserver needs to be set up in such a way that I can log in using ssh
and run the dns update script and it needs to be on a fixed IP (so I can
delegate the cable zone to it and I know where to
reach it when the connection comes up). It does not have to be the
same nameserver as for the main server.