Hello Costas,
thanks for sending your patch here and once again for sending the same patch as a pull request on github.
I really don't know, why your first mail did not appear in my inbox, nor got displayed on our patchwork infrastructure.
After a quick code review and some basic testing with invalid data, everything seems to work and I finally merged your patchset.
In addition to this I tagged a new version of ddns, which will be part of one of the next upcomming Core updates.
Best regards,
-Stefan