What came first: the CNAME or the A record?
A change to 1.1.1.1 inadvertently modified CNAME record order in DNS responses, disrupting some clients, prompting an investigation into resolver source code and DNS RFC ambiguities.
MAIN POINTS
- A recent update to 1.1.1.1 affected the order of CNAME records in DNS responses.
- The change caused resolution issues for certain DNS clients.
- The investigation included examining the source code of affected DNS resolvers.
- Ambiguities in DNS RFCs were identified as a contributing factor.
TAKEAWAYS
- DNS record order can impact client resolution functionality.
- Code reviews are essential when changes affect DNS infrastructure.
- Understanding DNS RFCs is crucial for proper implementation.
- Technical investigations can reveal underlying protocol ambiguities.