Besides IN and CH there is also HS aka Hesiod https://en.wikipedia.org/wiki/Hesiod_(name_service) https://en.wikipedia.org/wiki/Hesiod_(name_service) which is

Besides IN and CH there is also HS aka Hesiod https://en.wikipedia.org/wiki/Hesiod_(name_service) https://en.wikipedia.org/wiki/Hesiod_(name_service) which is from Project Athena: https://en.wikipedia.org/wiki/Project_Athena https://en.wikipedia.org/wiki/Project_Athena > Project Athena was a joint project of MIT, Digital Equipment Corporation, and IBM to produce a campus-wide distributed computing environment for educational use.