Your domain registrar does not do anything except mediate your ability to alter your DNS records and allow you to renew your domain name entries: it really shouldn't matter if they go offline unless they go offline for months at a time.

You thereby should never, under any circumstance where your domain's availability means anything to you at all, allow your domain name registrar to handle all of your DNS records (as many of the people in that "GoDaddy's DNS Service is Down" thread have done).

Instead, at least some of your authoritative DNS servers should be hosted by anyone other than your registrar: otherwise, you can end up in the situation where all of your DNS goes offline and you can't update your DNS records.

(Of course, you should really not have all of your DNS records hosted by a single company that doesn't have any internal redundancy in the first place; this criteria alone should exclude companies that don't really care about DNS, like any registrar ever, from being your only DNS provider.)

(Note: I'm not certain if today's outage of GoDaddy's DNS infrastructure affected anyone's ability to use their portal to update their DNS records, but one could easily imagine simple scenarios where that happens.)