What came first- the CNAME or the A record

This post details a DNS resolution incident caused by a change in the order of CNAME records within 1.1.1.1's responses. The change, intended to reduce memory usage, broke DNS clients that expected CNAMEs to appear before A/AAAA records, such as glibc's getaddrinfo and Cisco's DNSC process. The post explains the RFC 1034 ambiguity regarding the ordering of RRs in message sections versus RRsets, and how this led to the incident. It also discusses the importance of robust parsing logic in DNS clients to handle variations in response ordering.