Last Updated 2023-11-08 Available Formats XML HTML Plain text Registries included below DNS CLASSes Resource Record (RR) TYPEs DNS OpCodes DNS RCODEs AFSDB RR Subtype DHCID RR Identifier Type Codes DHCID RR Digest Type Codes DNS Label Types DNS EDNS0 Option Codes (OPT) DNS Header Flags EDNS Header Flags (16 bits) EDNS version Number (8 bits) Child Synchronization (CSYNC) Flags Underscored and Glob