What came first: the CNAME or the A record?
Summary
The article analyzes an incident where a DNS update reordered CNAME and A records, causing resolution failures for some clients. It explains how DNS record ordering is ambiguously defined in older RFCs, describes real-world impact on implementations like glibc's getaddrinfo and Cisco switches, and discusses RFC interpretations, resolver behavior, and the move to revert the change while proposing an IETF draft to clarify ordered responses.