RFC 2782: A DNS RR for specifying the location of services (DNS SRV)
RFC 2052: A DNS RR for specifying the location of services (DNS SRV)
A DNS RR for specifying the location of services (DNS SRV)
RFC 6335: Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number Registry
RFC 8553: DNS Attrleaf Changes: Fixing Specifications That Use Underscored Node Names
RFC 1034: Domain names - concepts and facilities
RFC 1035: Domain names - implementation and specification
RFC 974: Mail routing and the domain system
RFC 2119: Key words for use in RFCs to Indicate Requirement Levels