Relationship between DNS RFCs
https://emaillab.jp/dns/dns-rfc/DNS | IETF RFC | Network
The site contains two PDFs showing the relationship between the DNS RFCs. There is a simplified overview and a full overview. The graphs are regularly updated. The RFCs are organized by time, by topic area (e.g., DNSSEC, RR), and the RFC status (e.g., Standard, Best Current Practice).