CNAME and A Record Order Ambiguity Causes DNS Failures
⚠️ On January 8, 2026, a memory-optimizing change to Cloudflare’s 1.1.1.1 resolver inadvertently reordered DNS answer records, placing CNAMEs after final A/AAAA answers and triggering widespread resolution failures. The bug primarily affected clients that parse answers sequentially—most notably glibc getaddrinfo and certain Cisco switch firmware—resulting in failed lookups and reboot loops in some devices. Cloudflare reverted the change promptly and has drafted an IETF Internet‑Draft to clarify expected answer ordering.
