https://datatracker.ietf.org/doc/html/rfc2535
RFC 2535 - Domain Name System Security Extensions
Domain Name System Security Extensions (RFC 2535, ; obsoleted by RFC 4034, RFC 4035, RFC 4033)
domain name systemrfc 2535securityextensions
https://www.rfc-editor.org/info/rfc2535
Information on RFC 2535 ยป RFC Editor
rfc 2535informationeditor