IONOS DNS Updater
I created this so I would be able to automatically update my DNS settings for a 1and1 hosted domain to be somewhat synced up to my home IP address.
known issues
It seems after you run it a few times in a short period, it won't work since 1and1 will require a captcha. The fix for me has been to log on manually, then it seems to make 1and1 happy for a period of time.