Some registrars offer an API to their own (free) DNS service which makes it possible to update records automagically. An example of such is Gandi (https://gandi

Some registrars offer an API to their own (free) DNS service which makes it possible to update records automagically. An example of such is Gandi (https://gandi.net https://gandi.net), which also happens to be the one you use (according to whois). This way you're free to do any sort of DNS trickery, including simple dynamic updates through a cron job on the router. Given that you already have a domain with them and use the Gandi name servers it should be easy to set up something to do just what you want. You'll need to get an API key first, for more info check http://www.gandi.net/domain/api http://www.gandi.net/domain/api