I think it's fairer to say you got around to it because they're not checking. Even with a single machine it's still better to have redundant DNS. You want to b

I think it's fairer to say you got around to it because they're not checking. Even with a single machine it's still better to have redundant DNS. You want to be able to move around the machine to a new connection / IP, without having to wait for the registrars to update the IP of the DNS server; similarly when your one DNS provider is DDOSed, your site will stop working, but not if you had 2 different providers. So to answer your question: you as the operator will care, because you want to get things back up quickly ... I think for small servers it's much preferable to run a hidden primary (not publicly listed in DNS), and let secondary DNS servers update from there. That way you have complete control over your DNS, even when your machine goes down.