Domain Name System (DNS) Parameters
(last updated 2011-11-01)
Registries included below:
- DNS CLASSes
- Resource Record (RR) TYPEs
- DNS OpCodes
- DNS RCODEs
- AFSDB RR Subtype
- DHCID RR Identifier Type Codes
- DNS Label types
- DNS EDNS0 Options
- DNS Header Flags
- EDNS Header Flags (16 bits)
- EDNS Version Numbers (8 bits)
Registry Name: DNS CLASSes
Reference: [RFC6195]
Range
Decimal Hexadecimal Registration Procedures Notes
----------- ------------- ----------------------------- ----------------------
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 Reserved for Private Use
65535 0xFFFF Standards Action
Registry:
Decimal Hexadecimal Name Reference
----------- ----------- ------------------------------ ---------
0 0x0000 Reserved [RFC6195]
1 0x0001 Internet (IN) [RFC1035]
2 0x0002 Unassigned
3 0x0003 Chaos (CH) [Moon1981]
4 0x0004 Hesiod (HS) [Dyer1987]
5-253 0x0005-0x00FD Unassigned
254 0x00FD QCLASS NONE [RFC2136]
255 0x00FF QCLASS * (ANY) [RFC1035]
256-65279 0x0100-0xFEFF Unassigned
65280-65534 0xFF00-0xFFFE Reserved for Private Use [RFC6195]
65535 0xFFFF Reserved [RFC6195]
Registry Name: Resource Record (RR) TYPEs
Reference: [RFC6195][RFC1035]
Range
Decimal Hexadecimal Registration Procedures Notes
----------- ------------- -------------------------------------------------------------- --------------
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 DNS RRTYPE Allocation Policy data TYPEs
128-255 0x0080-0x00FF DNS RRTYPE Allocation Policy Q TYPEs, Meta TYPEs
256-61439 0x0100-0xEFFF DNS RRTYPE Allocation Policy data RRTYPEs
61440-65279 0xF000-0xFEFF IETF Review
65280-65534 0xFF00-0xFFFE Reserved for Private Use
65535 0xFFFF Reserved (Standards Action)
Registry:
TYPE Value and meaning Reference
----------- --------------------------------------------- ---------
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 [RFC1706]
NSAP-PTR 23 for domain name pointer, NSAP style [RFC1348][RFC1637][RFC1706]
SIG 24 for security signature [RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2931][RFC3110][RFC3008]
KEY 25 for security key [RFC4034][RFC3755][RFC2535][RFC2536][RFC2537][RFC2539][RFC3008][RFC3110]
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 [RFC3755][RFC2535]
EID 31 Endpoint Identifier [Patton][Patton1995]
NIMLOC 32 Nimrod Locator [Patton][Patton1995]
SRV 33 Server Selection [RFC2782]
ATMA 34 ATM Address [ATMDOC]
NAPTR 35 Naming Authority Pointer [RFC2915][RFC2168][RFC3403]
KX 36 Key Exchanger [RFC2230]
CERT 37 CERT [RFC4398]
A6 38 A6 (Experimental) [RFC3226][RFC2874]
DNAME 39 DNAME [RFC2672]
SINK 40 SINK [Eastlake][Eastlake2002]
OPT 41 OPT [RFC2671][RFC3225]
APL 42 APL [RFC3123]
DS 43 Delegation Signer [RFC4034][RFC3658]
SSHFP 44 SSH Key Fingerprint [RFC4255]
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]
Unassigned 52-54
HIP 55 Host Identity Protocol [RFC5205]
NINFO 56 NINFO [Reid]
RKEY 57 RKEY [Reid]
TALINK 58 Trust Anchor LINK [Wijngaards]
CDS 59 Child DS [Barwood]
Unassigned 60-98
SPF 99 [RFC4408]
UINFO 100 [IANA-Reserved]
UID 101 [IANA-Reserved]
GID 102 [IANA-Reserved]
UNSPEC 103 [IANA-Reserved]
Unassigned 104-248
TKEY 249 Transaction Key [RFC2930]
TSIG 250 Transaction Signature [RFC2845]
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 all records [RFC1035]
URI 256 URI [Faltstrom]
CAA 257 Certification Authority Authorization [Hallam-Baker]
Unassigned 258-32767
TA 32768 DNSSEC Trust Authorities [Weiler] 2005-12-13
DLV 32769 DNSSEC Lookaside Validation [RFC4431]
Unassigned 32770-65279
Private use 65280-65534
Reserved 65535
Note: 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
Registry Name: DNS OpCodes
Reference: [RFC6195][RFC1035]
Registration Procedures: Standards Action as modified by [RFC4020]
Registry:
OpCode Name Reference
------ --------------------------------- ---------
0 Query [RFC1035]
1 IQuery (Inverse Query, Obsolete) [RFC3425]
2 Status [RFC1035]
3 Unassigned
4 Notify [RFC1996]
5 Update [RFC2136]
6-15 Unassigned
Registry Name: DNS RCODEs
Reference: [RFC6195][RFC1035]
Registration Procedures: IETF Review
Registry:
RCODE
Decimal 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]
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]
10 NotZone Name not contained in zone [RFC2136]
11-15 Unassigned
16 BADVERS Bad OPT Version [RFC2671]
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]
23-3840 Unassigned
3841-4095 Reserved for Private Use [RFC6195]
4096-65534 Unassigned
65535 Reserved, can be allocated by Standards Action [RFC6195]
Registry Name: AFSDB RR Subtype
Reference: [RFC6195][RFC1035]
Range
Decimal Hexadecimal Registration Procedures
----------- ------------- --------------------------------------
0 0x0000 Standards Action
1-65279 0x0001-0xFEFF IETF Review
65280-65534 0xFF00-0xFFFE Private Use
65535 0xFFFF Standards Action
Registry:
Decimal Hexadecimal Description Reference
----------- ------------- ------------------------------------------ ---------
0 0x0000 Reserved [RFC6195]
1 0x0001 Andrews File Service v3.0 Location Service [RFC1183]
2 0x0002 DCE/NCA root cell directory node [RFC1183]
3-65279 0x0003-0xFEFF Unassigned
65280-65534 0xFF00-0xFFFE Reserved for Private Use [RFC6195]
65535 0xFFFF Reserved [RFC6195]
Registry Name: DHCID RR Identifier Type Codes
Reference: [RFC4701]
Registration Procedures: Standards Action
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].
The expert will be Olafur Gudmundsson
Registry:
Identifier Type Code Identifier Reference
-------------------- ------------------------------------------------ ---------
0x0000 The 1-octet 'htype' followed by 'hlen' octets [RFC4701]
of 'chaddr' from a DHCPv4 client's DHCPREQUEST.
0x0001 The data octets (i.e., the Type and [RFC4701]
Client-Identifier fields) from a DHCPv4
client's Client Identifier option.
0x0002 The client's DUID (i.e., the data octets of a [RFC4701]
DHCPv6 client's Client Identifier option
or the DUID field from a DHCPv4 client's
Client Identifier option).
0x0003-0xFFFE Unassigned [RFC4701]
0xFFFF Reserved [RFC4701]
Registry Name: DNS Label types
Reference: [RFC2671]
Registration Procedures: IESG Approval
Note:
IETF standards action required to allocate new types
The top 2 bits of the first byte of an DNS label indicates the type of label.
Registry:
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 Standard [RFC1035]
from next octet form a pointer to the compression target.
0 1 Extended label type the lower 6 bits of this type Proposed [RFC2671]
(section 3) indicate the type of label in use
0 1 0 0 0 0 0 1 Binary Label Experimental not recommended [RFC3364][RFC3363][RFC2673]
0 1 1 1 1 1 1 1 Reserved for future expansion. Proposed [RFC2671]
1 0 Unallocated
Registry Name: DNS EDNS0 Options
Reference: [RFC2671]
Registration Procedures: RFC Required
Registry:
Value Name Status Reference
-------- ---------- ----------- -----------
0 Reserved [RFC2671]
1 LLQ On-hold [http://files.dns-sd.org/draft-sekar-dns-llq.txt]
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]
5-65535 Unassigned [RFC2671]
Registry Name: DNS Header Flags
Reference: [RFC6195][RFC1035]
Registration Procedures: Standards Action
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)
Registry:
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 Allowed [RFC1035]
bit 9 Reserved
bit 10 AD Authentic Data [RFC4035]
bit 11 CD Checking Disabled [RFC4035]
Registry Name: EDNS Header Flags (16 bits)
Reference: [RFC2671]
Registration Procedures: RFC Required
Registry:
Bit Flag Description Reference
--------- ---- --------------------- ------------------
Bit 0 DO DNSSEC answer OK [RFC4035][RFC3225]
Bit 1-15 Reserved
Registry Name: EDNS version Number (8 bits)
Reference: [RFC2671]
Registration Procedures: Standards Action
Registry:
Range Description Reference
-------- ----------------------- ---------
0 EDNS version 0 [RFC2671]
1-255 Unassigned
References
----------
[ATMDOC] ATM Forum Technical Committee, "ATM Name System, V2.0",
Doc ID: AF-DANS-0152.000, July 2000. Available from
http://broadband-forum.org/ftp/pub/approved-specs/af-saa-0069.000.pdf
and held in escrow by IANA.
[Dyer1987] Dyer, S., and F. Hsu, "Hesiod", Project Athena Technical
Plan - Name Service, April 1987.
[Eastlake2002] http://bgp.potaroo.net/ietf/all-ids/draft-eastlake-kitchen-sink-02.txt
[Moon1981] D. Moon, "Chaosnet", A.I. Memo 628, Massachusetts Institute of
Technology Artificial Intelligence Laboratory, June 1981.
[Patton1995] http://ana-3.lcs.mit.edu/~jnc/nimrod/dns.txt
[RFC1002] "PROTOCOL STANDARD FOR A NetBIOS SERVICE ON A TCP/UDP TRANSPORT:
DETAILED SPECIFICATIONS", RFC 1002, March 1987.
[RFC1034] Mockapetris, P., "Domain Names - Concepts and
Facilities", STD 13, RFC 1034, USC/Information Sciences
Institute, November 1987.
[RFC1035] Mockapetris, P., "Domain Names - Implementation and
Specification", STD 13, RFC 1035, USC/Information Sciences
Institute, November 1987.
[RFC1183] Everhart, C., Mamakos, L., Ullmann, R., and P. Mockapetris,
Editors, "New DNS RR Definitions", RFC 1183, Transarc,
University of Maryland, Prime Computer, USC/Information
Sciences Institute, October 1990.
[RFC1348] B. Manning, "DNS NSAP RRs", RFC 1348, July 1992.
[RFC1637] B. Manning, R. Colella, "DNS NSAP Resource Records", June 1994.
[RFC1706] Manning, B., and R. Colella, "DNS NSAP Resource Records",
RFC 1706, USC/ISI and NIST, October 1994.
[RFC1712] Farrell, C., M. Schulze, B. Pleitner, and D. Baldoni, "DNS
Encoding of Geographical Location", RFC 1712, Curtin
University of Technology, October 1994.
[RFC1876] C. Davis, P. Vixie, T. Goodwin, and I. Dickinson, "A Means for
Expressing Location Information in the Domain Name System",
RFC 1876, January 1996.
[RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995,
Tokyo Institute of Technology, August 1996.
[RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone
Changes (DNS NOTIFY)", RFC 1996, ISC, August 1996.
[RFC2136] Vixie, P., S. Thomson, Y. Rekhter, and J. Bound, "Dynamic
Updates in the Domain Name System (DNS UPDATE) Dynamic
Updates in the Domain Name System (DNS UPDATE), RFC 2136,
ISC, Bellcore, Cisco, DEC, April 1997.
[RFC2163] Allocchio, C., "Using the Internet DNS to Distribute MIXER
Conformant Global Address Mapping (MCGAM)", RFC 2163,
GARR-Italy, July 1977.
[RFC2168] R. Danie1, M. Mealling., "Resolution of Uniform Resource
Identifiers using the Domain Name System", RFC 2168, Los
Alamos National Laboratory, Network Solutions, Inc.,
June 1997.
[RFC2230] Atkinson, R., "Key Exchange Delegation Record for the DNS",
RFC 2230, NRL, October 1997.
[RFC2535] Eastlake, D., "Domain Name System Security Extensions", RFC
2535, IBM, March 1999.
[RFC2536] D. Eastlake, "DSA KEYs and SIGs in the Domain Name System (DNS)",
RFC 2536, March 1999.
[RFC2537] D. Eastlake, "RSA/MD5 KEYs and SIGs in the Domain Name System
(DNS)", RFC 2537, March 1999.
[RFC2539] D. Eastlake, "Storage of Diffie-Hellman Keys in the Domain Name
System (DNS)", RFC 2539, March 1999.
[RFC2671] Vixie, P., "Extension Mechanisms for DNS (EDNS0)", RFC 2671,
August 1999.
[RFC2672] M. Crawford, "Non-Terminal DNS Name Redirection", RFC 2672,
August 1999.
[RFC2673] M. Crawford, "Binary Labels in the Domain Name System",
RFC 2673, August 1999.
[RFC2782] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR for
Specifying the Location of Services (DNS SRV)", RFC 2782,
February 2000.
[RFC2845] Vixie, P., Gudmundsson, O., Eastlake, D. and B. Wellington,
"Secret Key Transaction Authentication for DNS (TSIG)",
May 2000.
[RFC2874] Crawford, M., Huitema, C. and S. Thomson, "DNS Extensions to
Support IPv6 Address Aggregation and Renumbering", RFC 2874,
July 2000.
[RFC2915] Mealling, M. and R. Daniel, "The Naming Authority Pointer
(NAPTR) DNS Resource Record", RFC 2915, September 2000.
[RFC2930] Eastlake, D., "Secret Key Establishment for DNS (TKEY RR)",
RFC 2930, September 2000.
[RFC2931] D. Eastlake, "DNS Request and Transaction Signatures ( SIG(0)s )",
RFC 2931, September 2000.
[RFC3008] B. Wellington, "Domain Name System Security (DNSSEC) Signing
Authority", RFC 3008, November 2000.
[RFC3110] D. Eastlake, "RSA/SHA-1 SIGs and RSA KEYs in the Domain Name
System (DNS)", RFC 3110, May 2001.
[RFC3123] P. Koch, "A DNS RR Type for Lists of Address Prefixes (APL RR)",
RFC 3123, June 2001.
[RFC3225] D. Conrad, "Indicating Resolver Support of DNSSEC",
RFC 3225, December 2001.
[RFC3226] O. Gudmundsson, "DNSSEC and IPv6 A6 aware server/resolver message
size requirements", RFC 3226, December 2001.
[RFC3363] R. Bush, A. Durand, B. Fink, O. Gudmundsson, T. Hain, Eds.,
"Representing Internet Protocol version 6 (IPv6) Addresses in
the Domain Name System (DNS)", RFC 3363, August 2002.
[RFC3364] R. Austein, "Tradeoffs in Domain Name System (DNS) Support
for Internet Protocol version 6 (IPv6)", RFC 3364, August 2002.
[RFC3403] M. Mealling, "Dynamic Delegation Discovery System (DDDS) Part
Three: The Domain Name System (DNS) Database", RFC 3403, October
2002.
[RFC3425] D. Lawrence, "Obsoleting IQUERY", RFC 3425, November 2002.
[RFC3596] S. Thomson, C. Huitema, V. Ksinant, and M. Souissi, "DNS
Extensions to Support IP Version 6", RFC 3596, October 2003.
[RFC3658] O. Gudmundsson, "Delegation Signer Resource Record", RFC 3658,
December 2003.
[RFC3755] S. Weiler, "Legacy Resolver Compatibility for Delegation Signer",
RFC 3755, May 2004.
[RFC4020] K. Kompella, A. Zinin, "Early IANA Allocation of Standards Track
Code Points", RFC 4020, February 2005.
[RFC4025] M. Richardson, "A Method for Storing IPsec Keying Material in DNS",
RFC 4025, March 2005.
[RFC4034] R. Arends, R. Austein, M. Larson, D. Massey, and S. Rose,
"Resource Records for the DNS Security Extensions", RFC 4034,
March 2005.
[RFC4035] R. Arends, R. Austein, M. Larson, D. Massey, and S. Rose,
"Protocol Modifications for the DNS Security Extensions",
RFC 4035, March 2005.
[RFC4255] J. Schlyter and W. Griffin, "Using DNS to Securely Publish SSH
Key Fingerprints", RFC 4255, January 2006.
[RFC4398] S. Josefsson, "Storing Certificates in the Domain Name System (DNS)",
RFC 4398, March 2006.
[RFC4408] M. Wong and W. Schlitt, "Sender Policy Framework (SPF) for Authorizing
Use of Domains in E-MAIL, version 1", RFC 4408, April 2006.
[RFC4431] M. Andrews and S. Weiler, "The DNSSEC Lookaside Validation (DLV)
DNS Resource Record", RFC 4431, February 2006.
[RFC4635] D. Eastlake 3rd, "HMAC SHA TSIG Algorithm Identifiers", RFC 4635,
August 2006.
[RFC4701] M. Stapp, T. Lemon, A. Gustafsson, "A DNS RR for Encoding DHCP
Information (DHCID RR)", RFC 4701, October 2006.
[RFC5001] R. Austein, "DNS Name Server Identifier Option (NSID)",
RFC 5001, August 2007.
[RFC5155] B. Laurie, G. Sisson, R. Arends, D. Blacka, "DNSSEC Hashed
Authenticated Denial of Existence", RFC 5155, March 2008.
[RFC5205] P. Nikander, J. Laganier, "Host Identity Protocol (HIP)
Domain Name System (DNS) Extensions", RFC 5205, April 2008.
[draft-cheshire-edns0-owner-option] work in progress
[RFC5864] R. Allbery, "DNS SRV Resource Records for AFS", RFC 5864, April 2010.
[RFC5936] E. Lewis, A. Hoenes, Ed., "DNS Zone Transfer Protocol (AXFR)",
RFC 5936, June 2010.
[RFC6195] D. Eastlake, "Domain Name System (DNS) IANA
Considerations", RFC 6195, March 2011.
People
--------
[Barwood] George Barwood, , 06 June 2011.
[Daniel] Ron Daniel, , June 1997.
[Eastlake] Donald E. Eastlake, III , January 1995,
November 1997.
[Faltstrom] Patrik Faltstrom, , 22 February 2011.
[Hallam-Baker] Phillip Hallam-Baker, , 07 April 2011.
[IANA] Internet Assigned Numbers Authority, , December 1994.
[Mockapetris] Paul Mockapetris, , November 1994.
[Otha] Masataka Ohta, , March 1995.
[Patton] Michael Patton, , June 1995.
[Reid] Jim Reid, , 21 January 2008.
[Thomson] Susan Thomson, , August 1995.
[Vixie] Paul Vixie, , June 1997.
[Weiler] Sam Weiler, , December 2005.
Deploying DNSSEC Without a Signed Root. Technical Report 1999-19,
Information Networking Institute, Carnegie Mellon University, April 2004.
http://cameo.library.cmu.edu/
http://www.watson.org/~weiler/INI1999-19.pdf
[Wijngaards] Wouter Wijngaards, , 2010-02-17.
[]
http://www.iana.org/assignments/dns-parameters