https://labs.ripe.net/author/bert_hubert/introducing-tdns-the-teachable-authoritative-dns-server/
Introducing 'tdns': the Teachable Authoritative DNS Server | RIPE Labs
tdns is part of the 'hello-dns' effort to provide a good entry point into DNS. tdns is small enough to read in one sitting and shows how DNS packets are parsed...
authoritative dns serverripe labsintroducingtdnsteachable