Domain Name System (DNS) Parameters

Last Updated: 2025-07-01
Available Formats: XML
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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
Extended DNS Error Codes
ZONEMD Schemes
ZONEMD Hash Algorithms
DNS Server Cookie Methods
DNS-over-QUIC Error Codes
DNS Catalog Zones Properties
DNS Resolver Information Keys
ZONEVERSION TYPE Values
DSYNC: Location of Synchronization Endpoints

DNS CLASSes

Expert(s)

Petr Špaček, Ladislav Lhotka

Reference

[RFC6895][RFC9108]

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.

Note

When this registry is modified, the YANG module [iana-dns-class-rr-type] 
must be updated as defined in [RFC9108].

Available Formats

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, Ólafur Guðmundsson, Ray Bellis

Reference

[RFC6895][RFC1035][RFC9108]

Note

When this registry is modified, the YANG module [iana-dns-class-rr-type] 
must be updated as defined in [RFC9108].

Available Formats

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
Reserved	0		[RFC6895]		2021-03-08
A	1	a host address	[RFC1035]
NS	2	an authoritative name server	[RFC1035]
MD	3	a mail destination (OBSOLETE - use MX)	[RFC1035]
MF	4	a mail forwarder (OBSOLETE - use MX)	[RFC1035]
CNAME	5	the canonical name for an alias	[RFC1035]
SOA	6	marks the start of a zone of authority	[RFC1035]
MB	7	a mailbox domain name (EXPERIMENTAL)	[RFC1035]
MG	8	a mail group member (EXPERIMENTAL)	[RFC1035]
MR	9	a mail rename domain name (EXPERIMENTAL)	[RFC1035]
NULL	10	a null RR (EXPERIMENTAL)	[RFC1035]
WKS	11	a well known service description	[RFC1035]
PTR	12	a domain name pointer	[RFC1035]
HINFO	13	host information	[RFC1035]
MINFO	14	mailbox or mail list information	[RFC1035]
MX	15	mail exchange	[RFC1035]
TXT	16	text strings	[RFC1035]
RP	17	for Responsible Person	[RFC1183]
AFSDB	18	for AFS Data Base location	[RFC1183][RFC5864]
X25	19	for X.25 PSDN address	[RFC1183]
ISDN	20	for ISDN address	[RFC1183]
RT	21	for Route Through	[RFC1183]
NSAP	22	for NSAP address, NSAP style A record (DEPRECATED)	[RFC1706][Moving TPC.INT and NSAP.INT infrastructure domains to historic]
NSAP-PTR	23	for domain name pointer, NSAP style (DEPRECATED)	[RFC1706][Moving TPC.INT and NSAP.INT infrastructure domains to historic]
SIG	24	for security signature	[RFC2536][RFC2931][RFC3110][RFC4034]
KEY	25	for security key	[RFC2536][RFC2539][RFC3110][RFC4034]
PX	26	X.400 mail mapping information	[RFC2163]
GPOS	27	Geographical Position	[RFC1712]
AAAA	28	IP6 Address	[RFC3596]
LOC	29	Location Information	[RFC1876]
NXT	30	Next Domain (OBSOLETE)	[RFC2535][RFC3755]
EID	31	Endpoint Identifier	[Michael_Patton][http://ana-3.lcs.mit.edu/~jnc/nimrod/dns.txt]		1995-06
NIMLOC	32	Nimrod Locator	[1][Michael_Patton][http://ana-3.lcs.mit.edu/~jnc/nimrod/dns.txt]		1995-06
SRV	33	Server Selection	[1][RFC2782]
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.]
NAPTR	35	Naming Authority Pointer	[RFC3403]
KX	36	Key Exchanger	[RFC2230]
CERT	37	CERT	[RFC4398]
A6	38	A6 (OBSOLETE - use AAAA)	[RFC2874][RFC3226][RFC6563]
DNAME	39	DNAME	[RFC6672]
SINK	40	SINK	[Donald_E_Eastlake][draft-eastlake-kitchen-sink-02]		1997-11
OPT	41	OPT	[RFC3225][RFC6891]
APL	42	APL	[RFC3123]
DS	43	Delegation Signer	[RFC4034]
SSHFP	44	SSH Key Fingerprint	[RFC4255]
IPSECKEY	45	IPSECKEY	[RFC4025]
RRSIG	46	RRSIG	[RFC4034]
NSEC	47	NSEC	[RFC4034][RFC9077]
DNSKEY	48	DNSKEY	[RFC4034]
DHCID	49	DHCID	[RFC4701]
NSEC3	50	NSEC3	[RFC5155][RFC9077]
NSEC3PARAM	51	NSEC3PARAM	[RFC5155]
TLSA	52	TLSA	[RFC6698]
SMIMEA	53	S/MIME cert association	[RFC8162]	SMIMEA/smimea-completed-template	2015-12-01
Unassigned	54
HIP	55	Host Identity Protocol	[RFC8005]
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 LINK	[Wouter_Wijngaards]	TALINK/talink-completed-template	2010-02-17
CDS	59	Child DS	[RFC7344]	CDS/cds-completed-template	2011-06-06
CDNSKEY	60	DNSKEY(s) the Child wants reflected in DS	[RFC7344]		2014-06-16
OPENPGPKEY	61	OpenPGP Key	[RFC7929]	OPENPGPKEY/openpgpkey-completed-template	2014-08-12
CSYNC	62	Child-To-Parent Synchronization	[RFC7477]		2015-01-27
ZONEMD	63	Message Digest Over Zone Data	[RFC8976]	ZONEMD/zonemd-completed-template	2018-12-12
SVCB	64	General-purpose service binding	[RFC9460]	SVCB/svcb-completed-template	2020-06-30
HTTPS	65	SVCB-compatible type for use with HTTP	[RFC9460]	HTTPS/https-completed-template	2020-06-30
DSYNC	66	Endpoint discovery for delegation synchronization	[RFC-ietf-dnsop-generalized-notify-09]	DSYNC/dsync-completed-template	2024-12-10
HHIT	67	Hierarchical Host Identity Tag	[draft-ietf-drip-registries-28]	HHIT/hhit-completed-template	2025-05-20
BRID	68	UAS Broadcast Remote Identification	[draft-ietf-drip-registries-28]	BRID/brid-completed-template	2025-05-20
Unassigned	69-98
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 address	[RFC7043]	EUI48/eui48-completed-template	2013-03-27
EUI64	109	an EUI-64 address	[RFC7043]	EUI64/eui64-completed-template	2013-03-27
Unassigned	110-127
NXNAME	128	NXDOMAIN indicator for Compact Denial of Existence	[RFC-ietf-dnsop-compact-denial-of-existence-07]	NXNAME/nxname-completed-template	2024-07-18
Unassigned	129-248
TKEY	249	Transaction Key	[RFC2930]
TSIG	250	Transaction Signature	[RFC8945]
IXFR	251	incremental transfer	[RFC1995]
AXFR	252	transfer of an entire zone	[RFC1035][RFC5936]
MAILB	253	mailbox-related RRs (MB, MG or MR)	[RFC1035]
MAILA	254	mail agent RRs (OBSOLETE - see MX)	[RFC1035]
*	255	A request for some or all records the server has available	[RFC1035][RFC6895][RFC8482]
URI	256	URI	[RFC7553]	URI/uri-completed-template	2011-02-22
CAA	257	Certification Authority Restriction	[RFC8659]	CAA/caa-completed-template	2011-04-07
AVC	258	Application Visibility and Control	[Wolfgang_Riedel]	AVC/avc-completed-template	2016-02-26
DOA	259	Digital Object Architecture	[draft-durand-doa-over-dns-02]	DOA/doa-completed-template	2017-08-30
AMTRELAY	260	Automatic Multicast Tunneling Relay	[RFC8777]	AMTRELAY/amtrelay-completed-template	2019-02-06
RESINFO	261	Resolver Information as Key/Value Pairs	[RFC9606]	RESINFO/resinfo-completed-template	2023-11-02
WALLET	262	Public wallet address	[Paul_Hoffman]	WALLET/wallet-completed-template	2024-06-21
CLA	263	BP Convergence Layer Adapter	[draft-johnson-dns-ipn-cla-07]	CLA/cla-completed-template	2024-07-25
IPN	264	BP Node Number	[draft-johnson-dns-ipn-cla-07]	IPN/ipn-completed-template	2024-07-25
Unassigned	265-32767
TA	32768	DNSSEC Trust Authorities	[Sam_Weiler][ Deploying DNSSEC Without a Signed Root. Technical Report 1999-19, Information Networking Institute, Carnegie Mellon University, April 2004.]		2005-12-13
DLV	32769	DNSSEC Lookaside Validation (OBSOLETE)	[RFC8749][RFC4431]
Unassigned	32770-65279
Private use	65280-65534
Reserved	65535

DNS OpCodes

Registration Procedure(s)

Standards Action

Reference

[RFC6895][RFC1035]

Available Formats

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: 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	[RFC8945]
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	[RFC8945]
17	BADKEY	Key not recognized	[RFC8945]
18	BADTIME	Signature out of time window	[RFC8945]
19	BADMODE	Bad TKEY Mode	[RFC2930]
20	BADNAME	Duplicate key name	[RFC2930]
21	BADALG	Algorithm not supported	[RFC2930]
22	BADTRUNC	Bad Truncation	[RFC8945]
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

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)

Ólafur Guðmundsson

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

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 DHCPv4 client's Client Identifier option).	[RFC4701]
0x0003-0xFFFE	Unassigned	[RFC4701]
0xFFFF	Reserved	[RFC4701]

DHCID RR Digest Type Codes

Registration Procedure(s)

Standards Action

Reference

[RFC4701]

Available Formats

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

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 the compression target.	Standard	[RFC1035]
0 1	Extended label type the lower 6 bits of this type (section 3) indicate the type of label in use	Proposed	[RFC6891]
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)

Ólafur Guðmundsson (primary), Frederico AC Neves (secondary), Ray Bellis (secondary), Roy Arends (secondary)

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

CSV

Range	Registration Procedures
1-65000	Expert Review
65001-65534	Local/Experimental Use

Value	Name	Status	Reference
0	Reserved		[RFC6891]
1	LLQ	Optional	[RFC8764]
2	Update Lease	Standard	[RFC9664]
3	NSID	Standard	[RFC5001]
4	Reserved		[draft-cheshire-edns0-owner-option-00]
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	Extended DNS Error	Standard	[RFC8914]
16	EDNS-Client-Tag	Optional	[draft-bellis-dnsop-edns-tags-01]
17	EDNS-Server-Tag	Optional	[draft-bellis-dnsop-edns-tags-01]
18	Report-Channel	Standard	[RFC9567]
19	ZONEVERSION	Standard	[RFC9660]
20	MQTYPE-Query	Optional	[draft-ietf-dnssd-multi-qtypes-07]
21	MQTYPE-Response	Optional	[draft-ietf-dnssd-multi-qtypes-07]
22-20291	Unassigned
20292	Umbrella Ident	Optional	[https://developer.cisco.com/docs/cloud-security/#!integrating-network-devices/rdata-description][Cisco_CIE_DNS_team]
20293-26945	Unassigned
26946	DeviceID	Optional	[https://developer.cisco.com/docs/cloud-security/#!network-devices-getting-started/response-codes][Cisco_CIE_DNS_team]
26947-65000	Unassigned
65001-65534	Reserved for Local/Experimental Use		[RFC6891]
65535	Reserved for future expansion		[RFC6891]

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

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

CSV

Bit	Flag	Description	Reference
Bit 0	DO	DNSSEC answer OK	[RFC4035][RFC3225][RFC6840][RFC Errata 4928]
Bit 1	CO	Compact Answers OK	[RFC-ietf-dnsop-compact-denial-of-existence-07]
Bit 2-15		Reserved

EDNS version Number (8 bits)

Registration Procedure(s)

Standards Action

Reference

[RFC6891]

Available Formats

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

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

CSV

RR Type	_NODE NAME	Reference
*	_example	[RFC8552, Section 4.1.4]
HTTPS	_https	[RFC9460]
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]
SVCB	_dns	[RFC9461]
TLSA	_dane	[RFC7671]
TLSA	_sctp	[RFC6698]
TLSA	_tcp	[RFC6698]
TLSA	_udp	[RFC6698]
TXT	_acme-challenge	[RFC8555]
TXT	_dmarc	[RFC-ietf-dmarc-dmarcbis-41]
TXT	_domainkey	[RFC6376]
TXT	_er	[RFC9567]
TXT	_mta-sts	[RFC8461]
TXT	_spf	[RFC7208]
TXT	_splitdns-challenge	[RFC9704]
TXT	_sztp	[RFC8572]
TXT	_tcp	[RFC6763]
TXT	_udp	[RFC6763]
TXT	_validation-contactemail	[https://cabforum.org/wp-content/uploads/CA-Browser-Forum-BR-1.7.4.pdf]
TXT	_validation-contactphone	[https://cabforum.org/wp-content/uploads/CA-Browser-Forum-BR-1.7.4.pdf]
TXT	_vouch	[RFC5518]
URI	_acct	[RFC7566][RFC Errata 7064]
URI	_dccp	[RFC4340][RFC Errata 7066]
URI	_email	[RFC6118]
URI	_ems	[RFC6118]
URI	_fax	[RFC6118]
URI	_ft	[RFC6118]
URI	_h323	[RFC6118]
URI	_iax	[RFC6315][RFC Errata 7065]
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	[RFC4340][RFC Errata 7067]
URI	_sip	[RFC6118]
URI	_sms	[RFC6118]
URI	_tcp	[RFC4340][RFC Errata 7068]
URI	_udp	[RFC4340][RFC Errata 7068]
URI	_unifmsg	[RFC6118]
URI	_vcard	[RFC6118]
URI	_videomsg	[RFC6118]
URI	_voice	[RFC6118]
URI	_voicemsg	[RFC6118]
URI	_vpim	[RFC6118]
URI	_web	[RFC6118]
URI	_xmpp	[RFC6118]
CDS	_signal	[RFC9615]
CDNSKEY	_signal	[RFC9615]
DSYNC	_dsync	[RFC-ietf-dnsop-generalized-notify-09]

DSO Type Codes

Expert(s)

Ted Lemon, Sara Dickinson, John Dickinson

Reference

[RFC8490]

Available Formats

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	SUBSCRIBE	OK	Standards Track	[RF8765, Section 6.2]
0x0041	PUSH	NO	Standards Track	[RF8765, Section 6.3]
0x0042	UNSUBSCRIBE	NO	Standards Track	[RF8765, Section 6.4]
0x0043	RECONFIRM	NO	Standards Track	[RF8765, Section 6.5]
0x0044-0xF7FF	Unassigned	NO
0xF800-0xFBFF	Reserved for Experimental/Local Use	NO		[RFC8490]
0xFC00-0xFFFF	Reserved for future expansion	NO

Extended DNS Error Codes

Reference: [RFC8914]
Available Formats: CSV

Range	Registration Procedures
0-49151	First Come First Served
49152-65535	Private Use

INFO-CODE	Purpose	Reference
0	Other Error	[RFC8914, Section 4.1]
1	Unsupported DNSKEY Algorithm	[RFC8914, Section 4.2]
2	Unsupported DS Digest Type	[RFC8914, Section 4.3]
3	Stale Answer	[RFC8914, Section 4.4][RFC8767]
4	Forged Answer	[RFC8914, Section 4.5]
5	DNSSEC Indeterminate	[RFC8914, Section 4.6]
6	DNSSEC Bogus	[RFC8914, Section 4.7]
7	Signature Expired	[RFC8914, Section 4.8]
8	Signature Not Yet Valid	[RFC8914, Section 4.9]
9	DNSKEY Missing	[RFC8914, Section 4.10]
10	RRSIGs Missing	[RFC8914, Section 4.11]
11	No Zone Key Bit Set	[RFC8914, Section 4.12]
12	NSEC Missing	[RFC8914, Section 4.13]
13	Cached Error	[RFC8914, Section 4.14]
14	Not Ready	[RFC8914, Section 4.15]
15	Blocked	[RFC8914, Section 4.16]
16	Censored	[RFC8914, Section 4.17]
17	Filtered	[RFC8914, Section 4.18]
18	Prohibited	[RFC8914, Section 4.19]
19	Stale NXDomain Answer	[RFC8914, Section 4.20]
20	Not Authoritative	[RFC8914, Section 4.21]
21	Not Supported	[RFC8914, Section 4.22]
22	No Reachable Authority	[RFC8914, Section 4.23]
23	Network Error	[RFC8914, Section 4.24]
24	Invalid Data	[RFC8914, Section 4.25]
25	Signature Expired before Valid	[https://github.com/NLnetLabs/unbound/pull/604#discussion_r802678343][Willem_Toorop]
26	Too Early	[RFC9250]
27	Unsupported NSEC3 Iterations Value	[RFC9276]
28	Unable to conform to policy	[draft-homburg-dnsop-codcp-00]
29	Synthesized	[https://github.com/PowerDNS/pdns/pull/12334][Otto_Moerbeek]
30	Invalid Query Type	[RFC-ietf-dnsop-compact-denial-of-existence-07]
31-49151	Unassigned
49152-65535	Reserved for Private Use	[RFC8914, Section 5.2]

ZONEMD Schemes

Expert(s)

Warren Kumari, Duane Wessels, Wes Hardaker

Reference

[RFC8976]

Available Formats

CSV

Range	Registration Procedures
1-239	Specification Required
240-254	Private Use

Value	Description	Mnemonic	Reference
0	Reserved		[RFC8976]
1	Simple ZONEMD collation	SIMPLE	[RFC8976]
2-239	Unassigned
240-254	Reserved for Private Use	N/A	[RFC8976]
255	Reserved		[RFC8976]

ZONEMD Hash Algorithms

Expert(s)

Warren Kumari, Duane Wessels, Wes Hardaker

Reference

[RFC8976]

Available Formats

CSV

Range	Registration Procedures
1-239	Specification Required
240-254	Private Use

Value	Description	Mnemonic	Reference
0	Reserved		[RFC8976]
1	SHA-384	SHA384	[RFC8976]
2	SHA-512	SHA512	[RFC8976]
3-239	Unassigned
240-254	Reserved for Private Use	N/A	[RFC8976]
255	Reserved		[RFC8976]

DNS Server Cookie Methods

Expert(s)

Ondřej Surý, Donald Eastlake

Reference

[RFC9018][RFC7873]

Note

A Server Cookie method (construction and pseudorandom algorithm)
is determined by the Version in the first byte of the Cookie and by
the Cookie size. Server Cookie size is limited to the inclusive
range of 8 to 32 bytes.

Available Formats

CSV

Range	Registration Procedures
Version 1-239, Size 8-32	Expert Review
Version 240-254, Size 8-32	Private Use

Version	Size	Method	Reference
0	8-32	Reserved	[RFC9018]
1	8-15	Unassigned
1	16	SipHash-2-4	[RFC9018]
1	17-32	Unassigned
2-239	8-32	Unassigned
240-254	8-32	Reserved for Private Use	[RFC9018]
255	8-32	Reserved	[RFC9018]

DNS-over-QUIC Error Codes

Expert(s)

Sara Dickinson, Christian Huitema

Reference

[RFC9250]

Available Formats

CSV

Range	Registration Procedures
provisional (greater than 0x3f)	Expert Review
provisional registration Date field update	First Come First Served
permanent, 0x00-0x3f	Standards Action or IESG Approval
permanent, greater than 0x3f	Specification Required

Value	Error	Description	Status	Specification	Date	Contact
0x0	DOQ_NO_ERROR	No error	permanent	[RFC9250, Section 4.3]	2022-04-01	[DPRIVE_WG]
0x1	DOQ_INTERNAL_ERROR	Implementation error	permanent	[RFC9250, Section 4.3]	2022-04-01	[DPRIVE_WG]
0x2	DOQ_PROTOCOL_ERROR	Generic protocol violation	permanent	[RFC9250, Section 4.3]	2022-04-01	[DPRIVE_WG]
0x3	DOQ_REQUEST_CANCELLED	Request cancelled by client	permanent	[RFC9250, Section 4.3]	2022-04-01	[DPRIVE_WG]
0x4	DOQ_EXCESSIVE_LOAD	Closing a connection for excessive load	permanent	[RFC9250, Section 4.3]	2022-04-01	[DPRIVE_WG]
0x5	DOQ_UNSPECIFIED_ERROR	No error reason specified	permanent	[RFC9250, Section 4.3]	2022-04-01	[DPRIVE_WG]
0xd098ea5e	DOQ_ERROR_RESERVED	Alternative error code used for tests	permanent	[RFC9250, Section 4.3]	2022-04-01	[DPRIVE_WG]

DNS Catalog Zones Properties

Expert(s)

Peter Thomassen, Ondřej Surý, Willem Toorop

Reference

[RFC9432]

Note

This registry applies to Catalog Zones schema version "2" as specified 
in [RFC9432].

Available Formats

CSV

Range	Registration Procedures
property prefix ends in the label "ext"	Private Use
all other property prefixes	Expert Review

Property Prefix	Description	Status	Reference
zones	List of member zones	Standards Track	[RFC9432]
version	Schema version	Standards Track	[RFC9432]
coo	Change of Ownership	Standards Track	[RFC9432]
group	Group	Standards Track	[RFC9432]
*.ext	Custom properties	Private Use	[RFC9432]

DNS Resolver Information Keys

Registration Procedure(s)

Specification Required

Expert(s)

Tirumal Reddy, Mohamed Boucadair, Ben Schwartz

Reference

[RFC9606]

Available Formats

CSV

Name	Description	Reference
qnamemin	The presence of the key name indicates that QNAME minimisation is enabled.	[RFC9606]
exterr	Lists the set of enabled extended DNS errors. It must be an INFO-CODE decimal value in the [Extended DNS Error Codes] registry.	[RFC9606]
infourl	Provides a URL that points to unstructured resolver information that is used for troubleshooting.	[RFC9606]

ZONEVERSION TYPE Values

Expert(s)

Hugo Salgado, Mauricio Vergara Ereche, Duane Wessels

Reference

[RFC9660]

Available Formats

CSV

Range	Registration Procedures
0-245	Specification Required
246-254	Private Use
255	Reserved

ZONEVERSION TYPE	Mnemonic	Reference
0	SOA-SERIAL	[RFC9660]
1-245	Unassigned
246-254	Reserved for Private Use	[RFC9660]
255	Reserved	[RFC9660]

DSYNC: Location of Synchronization Endpoints

Registration Procedure(s)

Expert Review

Expert(s)

Unassigned

Reference

[RFC-ietf-dnsop-generalized-notify-09]

Available Formats

CSV

RRtype	Scheme	Mnemonic	Purpose	Reference
	0		Null scheme (no-op)	[RFC-ietf-dnsop-generalized-notify-09]
CDS	1	NOTIFY	Delegation management	[RFC-ietf-dnsop-generalized-notify-09]
CSYNC	1	NOTIFY	Delegation management	[RFC-ietf-dnsop-generalized-notify-09]
	2-127		Unassigned
	128-255		Reserved for Private Use	[RFC-ietf-dnsop-generalized-notify-09]

Contact Information

ID	Name	Contact URI	Last Updated
[Cisco_CIE_DNS_team]	Cisco CIE DNS team	mailto:cie-eng.dns-team&cisco.com	2021-08-31
[Donald_E_Eastlake]	Donald E. Eastlake, III	mailto:d3e3e3&gmail.com	1997-11
[DPRIVE_WG]	DPRIVE working group	mailto:dns-privacy&ietf.org	2022-04-01
[Jim_Reid]	Jim Reid	mailto:jim&telnic.org	2008-01-21
[Michael_Patton]	Michael Patton	mailto:map&bbn.com	1995-06
[Otto_Moerbeek]	Otto Moerbeek	mailto:otto.moerbeek&powerdns.com	2023-03-29
[Paul_Hoffman]	Paul Hoffman	mailto:paul.hoffman&icann.org	2024-07-01
[Sam_Weiler]	Sam Weiler	mailto:weiler+iana&tislabs.com	2005-12
[Willem_Toorop]	Willem Toorop	mailto:willem&nlnetlabs.nl	2022-02-11
[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.