What came first: the CNAME or the A record?

This was reposted a few days later and sparked a more interesting discussion at https://news.ycombinator.com/item?id=46681611

I love this low-level stuff. Do you think this is the reason that in the past year or two DNS providers have stopped allowing CNAME records for the root domain? Meaning, it's to ensure backwards compatibility for certain DNS resolution tools that are order sensitive to not get confused?

The almost as interesting takeaway I have (which I am sure is in their internal postmortem) is that they presumably don't have any usage of glibc getaddrinfo clients in their release regression testing.