Domain Name System (DNS) Parameters Last Updated 2019-08-26 Available Formats [IMG] XML [IMG] HTML [IMG] 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 Globally Scoped DNS Node Names * DSO Type Codes DNS CLASSes Expert(s) Unassigned Reference [RFC6895] Note As noted in [RFC6762], Multicast DNS can only carry DNS records with classes in the range 0-32767. Classes in the range 32768 to 65535 are incompatible with Multicast DNS. Available Formats [IMG] CSV Decimal Hex Registration Procedures Note 0 0x0000 Standards Action 1-127 0x0000-0x007F IETF Review data CLASSes only 128-253 0x0080-0x00FD IETF Review QCLASSes and meta-CLASSes only 256-32767 0x0100-0x7FFF IETF Review 32768-57343 0x8000-0xDFFF Specification Required data CLASSes only 57344-65279 0xE000-0xFEFF Specification Required QCLASSes and meta-CLASSes only 65280-65534 0xFF00-0xFFFE Private Use 65535 0xFFFF Standards Action Decimal Hexadecimal Name Reference 0 0x0000 Reserved [RFC6895] 1 0x0001 Internet (IN) [RFC1035] 2 0x0002 Unassigned 3 0x0003 Chaos (CH) [D. Moon, "Chaosnet", A.I. Memo 628, Massachusetts Institute of Technology Artificial Intelligence Laboratory, June 1981.] 4 0x0004 Hesiod (HS) [Dyer, S., and F. Hsu, "Hesiod", Project Athena Technical Plan - Name Service, April 1987.] 5-253 0x0005-0x00FD Unassigned 254 0x00FE QCLASS NONE [RFC2136] 255 0x00FF QCLASS * (ANY) [RFC1035] 256-65279 0x0100-0xFEFF Unassigned 65280-65534 0xFF00-0xFFFE Reserved for Private Use [RFC6895] 65535 0xFFFF Reserved [RFC6895] Resource Record (RR) TYPEs Expert(s) Roy Arends, Frederico AC Neves, Olafur Gudmundsson, Ray Bellis Reference [RFC6895][RFC1035] Available Formats [IMG] CSV Decimal Hex Registration Procedures Note 0 0x0000 RRTYPE zero is used as a special indicator for the SIG RR [RFC2931], [RFC4034] and in other circumstances and must never be allocated for ordinary use. 1-127 0x0000-0x007F Expert Review (see mailing list information in [RFC6895]) or Standards Action data TYPEs 128-255 0x0080-0x00FF Expert Review (see mailing list information in [RFC6895]) or Standards Action Q TYPEs, Meta TYPEs 256-61439 0x0100-0xEFFF Expert Review (see mailing list information in [RFC6895]) or Standards Action data RRTYPEs 61440-65279 0xF000-0xFEFF Reserved for future use (IETF Review required to define use) 65280-65534 0xFF00-0xFFFE Private Use 65535 0xFFFF Reserved (Standards Action) TYPE Value Meaning Reference Template Registration Date A 1 a host address [RFC1035] an NS 2 authoritative [RFC1035] name server a mail MD 3 destination [RFC1035] (OBSOLETE - use MX) a mail MF 4 forwarder [RFC1035] (OBSOLETE - use MX) the canonical CNAME 5 name for an [RFC1035] alias marks the start SOA 6 of a zone of [RFC1035] authority a mailbox MB 7 domain name [RFC1035] (EXPERIMENTAL) a mail group MG 8 member [RFC1035] (EXPERIMENTAL) a mail rename MR 9 domain name [RFC1035] (EXPERIMENTAL) NULL 10 a null RR [RFC1035] (EXPERIMENTAL) a well known WKS 11 service [RFC1035] description PTR 12 a domain name [RFC1035] pointer HINFO 13 host [RFC1035] information mailbox or mail MINFO 14 list [RFC1035] information MX 15 mail exchange [RFC1035] TXT 16 text strings [RFC1035] RP 17 for Responsible [RFC1183] Person AFSDB 18 for AFS Data [RFC1183][RFC5864] Base location X25 19 for X.25 PSDN [RFC1183] address ISDN 20 for ISDN [RFC1183] address RT 21 for Route [RFC1183] Through for NSAP NSAP 22 address, NSAP [RFC1706] style A record for domain name NSAP-PTR 23 pointer, NSAP [RFC1348][RFC1637][RFC1706] style SIG 24 for security [RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2931][RFC3110][RFC3008] signature KEY 25 for security [RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2539][RFC3008][RFC3110] key X.400 mail PX 26 mapping [RFC2163] information GPOS 27 Geographical [RFC1712] Position AAAA 28 IP6 Address [RFC3596] LOC 29 Location [RFC1876] Information NXT 30 Next Domain [RFC3755][RFC2535] (OBSOLETE) EID 31 Endpoint [Michael_Patton][http://ana-3.lcs.mit.edu/~jnc/nimrod/dns.txt] 1995-06 Identifier NIMLOC 32 Nimrod Locator [1][Michael_Patton][http://ana-3.lcs.mit.edu/~jnc/nimrod/dns.txt] 1995-06 SRV 33 Server [1][RFC2782] Selection ATMA 34 ATM Address [ ATM Forum Technical Committee, "ATM Name System, V2.0", Doc ID: AF-DANS-0152.000, July 2000. Available from and held in escrow by IANA.] Naming NAPTR 35 Authority [RFC2915][RFC2168][RFC3403] Pointer KX 36 Key Exchanger [RFC2230] CERT 37 CERT [RFC4398] A6 38 A6 (OBSOLETE - [RFC3226][RFC2874][RFC6563] use AAAA) DNAME 39 DNAME [RFC6672] SINK 40 SINK [Donald_E_Eastlake][http://tools.ietf.org/html/draft-eastlake-kitchen-sink] 1997-11 OPT 41 OPT [RFC6891][RFC3225] APL 42 APL [RFC3123] DS 43 Delegation [RFC4034][RFC3658] Signer SSHFP 44 SSH Key [RFC4255] Fingerprint IPSECKEY 45 IPSECKEY [RFC4025] RRSIG 46 RRSIG [RFC4034][RFC3755] NSEC 47 NSEC [RFC4034][RFC3755] DNSKEY 48 DNSKEY [RFC4034][RFC3755] DHCID 49 DHCID [RFC4701] NSEC3 50 NSEC3 [RFC5155] NSEC3PARAM 51 NSEC3PARAM [RFC5155] TLSA 52 TLSA [RFC6698] SMIMEA 53 S/MIME cert [RFC8162] SMIMEA/smimea-completed-template 2015-12-01 association Unassigned 54 HIP 55 Host Identity [RFC8005] Protocol NINFO 56 NINFO [Jim_Reid] NINFO/ninfo-completed-template 2008-01-21 RKEY 57 RKEY [Jim_Reid] RKEY/rkey-completed-template 2008-01-21 TALINK 58 Trust Anchor [Wouter_Wijngaards] TALINK/talink-completed-template 2010-02-17 LINK CDS 59 Child DS [RFC7344] CDS/cds-completed-template 2011-06-06 DNSKEY(s) the CDNSKEY 60 Child wants [RFC7344] 2014-06-16 reflected in DS OPENPGPKEY 61 OpenPGP Key [RFC7929] OPENPGPKEY/openpgpkey-completed-template 2014-08-12 CSYNC 62 Child-To-Parent [RFC7477] 2015-01-27 Synchronization ZONEMD 63 message digest [draft-wessels-dns-zone-digest] ZONEMD/zonemd-completed-template 2018-12-12 for DNS zone Unassigned 64-98 SPF 99 [RFC7208] UINFO 100 [IANA-Reserved] UID 101 [IANA-Reserved] GID 102 [IANA-Reserved] UNSPEC 103 [IANA-Reserved] NID 104 [RFC6742] ILNP/nid-completed-template L32 105 [RFC6742] ILNP/l32-completed-template L64 106 [RFC6742] ILNP/l64-completed-template LP 107 [RFC6742] ILNP/lp-completed-template EUI48 108 an EUI-48 [RFC7043] EUI48/eui48-completed-template 2013-03-27 address EUI64 109 an EUI-64 [RFC7043] EUI64/eui64-completed-template 2013-03-27 address Unassigned 110-248 TKEY 249 Transaction Key [RFC2930] TSIG 250 Transaction [RFC2845] Signature IXFR 251 incremental [RFC1995] transfer AXFR 252 transfer of an [RFC1035][RFC5936] entire zone mailbox-related MAILB 253 RRs (MB, MG or [RFC1035] MR) mail agent RRs MAILA 254 (OBSOLETE - see [RFC1035] MX) A request for some or all * 255 records the [RFC1035][RFC6895][RFC8482] server has available URI 256 URI [RFC7553] URI/uri-completed-template 2011-02-22 Certification CAA 257 Authority [RFC-ietf-lamps-rfc6844bis-07] CAA/caa-completed-template 2011-04-07 Restriction Application AVC 258 Visibility and [Wolfgang_Riedel] AVC/avc-completed-template 2016-02-26 Control DOA 259 Digital Object [draft-durand-doa-over-dns] DOA/doa-completed-template 2017-08-30 Architecture Automatic AMTRELAY 260 Multicast [draft-ietf-mboned-driad-amt-discovery] AMTRELAY/amtrelay-completed-template 2019-02-06 Tunneling Relay Unassigned 261-32767 DNSSEC Trust [Sam_Weiler][http://cameo.library.cmu.edu/][ Deploying DNSSEC Without a TA 32768 Authorities Signed Root. Technical Report 1999-19, Information Networking Institute, 2005-12-13 Carnegie Mellon University, April 2004.] DNSSEC DLV 32769 Lookaside [RFC4431] Validation Unassigned 32770-65279 Private 65280-65534 use Reserved 65535 DNS OpCodes Registration Procedure(s) Standards Action Reference [RFC6895][RFC1035] Available Formats [IMG] CSV OpCode Name Reference 0 Query [RFC1035] 1 IQuery (Inverse Query, OBSOLETE) [RFC3425] 2 Status [RFC1035] 3 Unassigned 4 Notify [RFC1996] 5 Update [RFC2136] 6 DNS Stateful Operations (DSO) [RFC8490] 7-15 Unassigned DNS RCODEs Reference [RFC6895][RFC1035] Available Formats [IMG] CSV Range Registration Procedures 0-3840 IETF Review 3841-4095 Private Use 4096-65534 IETF Review 65535 Reserved (Standards Action) RCODE Name Description Reference 0 NoError No Error [RFC1035] 1 FormErr Format Error [RFC1035] 2 ServFail Server Failure [RFC1035] 3 NXDomain Non-Existent Domain [RFC1035] 4 NotImp Not Implemented [RFC1035] 5 Refused Query Refused [RFC1035] 6 YXDomain Name Exists when it should not [RFC2136][RFC6672] 7 YXRRSet RR Set Exists when it should not [RFC2136] 8 NXRRSet RR Set that should exist does not [RFC2136] 9 NotAuth Server Not Authoritative for zone [RFC2136] 9 NotAuth Not Authorized [RFC2845] 10 NotZone Name not contained in zone [RFC2136] 11 DSOTYPENI DSO-TYPE Not Implemented [RFC8490] 12-15 Unassigned 16 BADVERS Bad OPT Version [RFC6891] 16 BADSIG TSIG Signature Failure [RFC2845] 17 BADKEY Key not recognized [RFC2845] 18 BADTIME Signature out of time window [RFC2845] 19 BADMODE Bad TKEY Mode [RFC2930] 20 BADNAME Duplicate key name [RFC2930] 21 BADALG Algorithm not supported [RFC2930] 22 BADTRUNC Bad Truncation [RFC4635] 23 BADCOOKIE Bad/missing Server Cookie [RFC7873] 24-3840 Unassigned 3841-4095 Reserved for Private Use [RFC6895] 4096-65534 Unassigned 65535 Reserved, can be allocated by Standards Action [RFC6895] AFSDB RR Subtype Registration Procedure(s) Registry closed per [RFC6895] Reference [RFC6895][RFC1035] Available Formats [IMG] CSV Decimal Hexadecimal Description Reference 0 0x0000 Reserved; registry closed [RFC6895] 1 0x0001 Andrews File Service v3.0 Location Service [RFC1183] 2 0x0002 DCE/NCA root cell directory node [RFC1183] 3-65279 0x0003-0xFEFF Not allocated; registry closed 65280-65534 0xFF00-0xFFFE Reserved for Private Use [RFC6895] 65535 0xFFFF Reserved; registry closed [RFC6895] DHCID RR Identifier Type Codes Registration Procedure(s) Standards Action Expert(s) Olafur Gudmundsson Reference [RFC4701] Note Registration rules to be as follows: New DHCID RR type codes are tentatively assigned after the specification for the associated type code, published as an Internet Draft, has received expert review by a designated expert. The final assignment of DHCID RR type codes is through Standards Action, as defined in [RFC2434]. Available Formats [IMG] CSV Identifier Type Code Identifier Reference 0x0000 The 1-octet 'htype' followed by 'hlen' octets of 'chaddr' from a DHCPv4 client's DHCPREQUEST. [RFC4701] 0x0001 The data octets (i.e., the Type and Client-Identifier fields) from a DHCPv4 client's Client Identifier option. [RFC4701] 0x0002 The client's DUID (i.e., the data octets of a DHCPv6 client's Client Identifier option or the DUID field from a [RFC4701] DHCPv4 client's Client Identifier option). 0x0003-0xFFFE Unassigned [RFC4701] 0xFFFF Reserved [RFC4701] DHCID RR Digest Type Codes Registration Procedure(s) Standards Action Reference [RFC4701] Available Formats [IMG] CSV Digest Type Code Description Reference 0 Reserved [RFC4701] 1 SHA-256 [RFC4701] 2-255 Unassigned DNS Label Types Registration Procedure(s) Standards Action Reference [RFC6891] Note The top 2 bits of the first byte of an DNS label indicate the type of label. Available Formats [IMG] CSV Value Type Status Reference 0 0 Normal label lower 6 bits is the length of the label Standard [RFC1035] 1 1 Compressed label the lower 6 bits and the 8 bits from next octet form a pointer to Standard [RFC1035] the compression target. 0 1 Extended label type the lower 6 bits of this type (section 3) indicate the type of Proposed [RFC6891] label in use 0 1 0 0 0 0 0 1 Binary Label Historic [RFC3364][RFC3363][RFC2673][RFC6891] 0 1 1 1 1 1 1 1 Reserved for future expansion. Proposed [RFC6891] 1 0 Unallocated DNS EDNS0 Option Codes (OPT) Expert(s) Olafur Gudmundsson Reference [RFC6891][RFC Errata 3604] Note Registrations made by standards-track documents are listed as "Standard," and by non-standards-track documents as "Optional." Registrations for which there are no final specifications are listed as "On-Hold." Available Formats [IMG] CSV Range Registration Procedures 1-65000 Expert Review 65001-65534 Local/Experimental Use Value Name Status Reference 0 Reserved [RFC6891] 1 LLQ Optional [RFC-sekar-dns-llq-06] 2 UL On-hold [http://files.dns-sd.org/draft-sekar-dns-ul.txt] 3 NSID Standard [RFC5001] 4 Reserved [draft-cheshire-edns0-owner-option] 5 DAU Standard [RFC6975] 6 DHU Standard [RFC6975] 7 N3U Standard [RFC6975] 8 edns-client-subnet Optional [RFC7871] 9 EDNS EXPIRE Optional [RFC7314] 10 COOKIE Standard [RFC7873] 11 edns-tcp-keepalive Standard [RFC7828] 12 Padding Standard [RFC7830] 13 CHAIN Standard [RFC7901] 14 edns-key-tag Optional [RFC8145] 15 Unassigned 16 EDNS-Client-Tag Optional [draft-bellis-dnsop-edns-tags] 17 EDNS-Server-Tag Optional [draft-bellis-dnsop-edns-tags] 18-26945 Unassigned 26946 DeviceID Optional [https://docs.umbrella.com/developer/networkdevices-api/identifying-dns-traffic2][Brian_Hartvigsen] 26947-65000 Unassigned 65001-65534 Reserved for [RFC6891] Local/Experimental Use 65535 Reserved for future [RFC6891] expansion DNS Header Flags Registration Procedure(s) Standards Action Reference [RFC6895][RFC1035] Note In DNS query header there is a flag field in the second 16 bit word in query from bit 5 through bit 11 ([RFC1035] section 4.1.1) Available Formats [IMG] CSV Bit Flag Description Reference bit 5 AA Authoritative Answer [RFC1035] bit 6 TC Truncated Response [RFC1035] bit 7 RD Recursion Desired [RFC1035] bit 8 RA Recursion Available [RFC1035] bit 9 Reserved bit 10 AD Authentic Data [RFC4035][RFC6840][RFC Errata 4924] bit 11 CD Checking Disabled [RFC4035][RFC6840][RFC Errata 4927] EDNS Header Flags (16 bits) Registration Procedure(s) Standards Action Reference [RFC6891] Available Formats [IMG] CSV Bit Flag Description Reference Bit 0 DO DNSSEC answer OK [RFC4035][RFC3225][RFC6840][RFC Errata 4928] Bit 1-15 Reserved EDNS version Number (8 bits) Registration Procedure(s) Standards Action Reference [RFC6891] Available Formats [IMG] CSV Range Description Reference 0 EDNS version 0 [RFC6891] 1-255 Unassigned Child Synchronization (CSYNC) Flags Registration Procedure(s) Standards Action Reference [RFC7477] Available Formats [IMG] CSV Bit Flag Description Reference 0 immediate Immediately process this CSYNC record. [RFC7477, Section 3] 1 soaminimum Require a SOA serial number greater than the one specified. [RFC7477, Section 2.1.1.1] 2-15 Unassigned Underscored and Globally Scoped DNS Node Names Registration Procedure(s) Expert Review Expert(s) Frederico A C Neves, Paul Wouters Reference [RFC8552] Available Formats [IMG] CSV RR Type _NODE NAME Reference * _example [RFC8552, Section 4.1.4] NULL _ta-* [2] [RFC8145] OPENPGPKEY _openpgpkey [RFC7929] SMIMEA _smimecert [RFC8162] SRV _dccp [RFC2782] SRV _http [RFC4386] SRV _ipv6 [RFC5026] SRV _ldap [RFC4386] SRV _ocsp [RFC4386] SRV _sctp [RFC2782] SRV _sip [RFC5509] SRV _tcp [RFC2782] SRV _udp [RFC2782] SRV _xmpp [RFC3921] TLSA _dane [RFC7671] TLSA _sctp [RFC6698] TLSA _tcp [RFC6698] TLSA _udp [RFC6698] TXT _acme-challenge [RFC8555] TXT _dmarc [RFC7489] TXT _domainkey [RFC6376] TXT _mta-sts [RFC8461] TXT _spf [RFC7208] TXT _sztp [RFC8572] TXT _tcp [RFC6763] TXT _udp [RFC6763] TXT _vouch [RFC5518] URI _acct [RFC6118] URI _dccp [RFC7566] URI _email [RFC6118] URI _ems [RFC6118] URI _fax [RFC6118] URI _ft [RFC6118] URI _h323 [RFC6118] URI _iax [RFC6118] URI _ical-access [RFC6118] URI _ical-sched [RFC6118] URI _ifax [RFC6118] URI _im [RFC6118] URI _mms [RFC6118] URI _pres [RFC6118] URI _pstn [RFC6118] URI _sctp [RFC6118] URI _sip [RFC6118] URI _sms [RFC6118] URI _tcp [RFC6118] URI _udp [RFC6118] URI _unifmsg [RFC6118] URI _vcard [RFC6118] URI _videomsg [RFC6118] URI _voice [RFC6118] URI _voicemsg [RFC6118] URI _vpim [RFC6118] URI _web [RFC6118] URI _xmpp [RFC6118] DSO Type Codes Expert(s) Ted Lemon, Sara Dickinson, John Dickinson Reference [RFC8490] Available Formats [IMG] CSV Range Registration Procedures 0x0004-0x003F Standards Action 0x0040-0xF7FF Expert Review 0xF800-0xFBFF Experimental/Local Use 0xFC00-0xFFFF Standards Action Type Name Early Data Status Reference 0x0000 Reserved NO Standards Track [RFC8490] 0x0001 KeepAlive OK Standards Track [RFC8490] 0x0002 RetryDelay NO Standards Track [RFC8490] 0x0003 EncryptionPadding NA Standards Track [RFC8490] 0x0004-0x003F Unassigned, reserved for DSO session-management TLVs NO 0x0040-0xF7FF Unassigned NO 0xF800-0xFBFF Reserved for Experimental/Local Use NO [RFC8490] 0xFC00-0xFFFF Reserved for future expansion NO People ID Name Contact URI Last Updated [Brian_Hartvigsen] Brian Hartvigsen mailto:bhartvig&cisco.com 2016-12-09 [Donald_E_Eastlake] Donald E. Eastlake, III mailto:d3e3e3&gmail.com 1997-11 [George_Barwood] George Barwood mailto:george.barwood&blueyonder.co.uk 2011-06-06 [Jim_Reid] Jim Reid mailto:jim&telnic.org 2008-01-21 [Michael_Patton] Michael Patton mailto:map&bbn.com 1995-06 [Patrik_Faltstrom] Patrik Fältström mailto:paf&frobbit.se 2015-01-05 [Phillip_Hallam_Baker] Phillip Hallam-Baker mailto:phill&hallambaker.com 2011-04-07 [Sam_Weiler] Sam Weiler mailto:weiler+iana&tislabs.com 2005-12 [Wolfgang_Riedel] Wolfgang Riedel mailto:wolfgang&cisco.com 2016-02-26 [Wouter_Wijngaards] Wouter Wijngaards mailto:wouter&nlnetlabs.nl 2010-02-17 Footnotes [1] In [RFC1002], two types are defined. It is not clear that these are in use, though if so their assignment does conflict with those above. NB 32 NetBIOS general Name Service NBSTAT 33 NetBIOS NODE STATUS [2] From [RFC8552, Section 4.1.3 _ta]: Under the NULL RR, the entry "_ta-*" denotes all node names beginning with the string "_ta-*". It does NOT refer to a DNS wildcard specification.