From http://www.iana.org/assignments/dns-parameters


(last updated 11 July 2005)

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]
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 

SIG             24 for security signature                 [RFC2535], [RFC3755], [RFC4034]
KEY             25 for security key                       [RFC2535], [RFC3755], [RFC4034]

PX              26 X.400 mail mapping information         [RFC2163]

GPOS            27 Geographical Position                  [RFC1712]

AAAA            28 IP6 Address                            [Thomson]

LOC             29 Location Information                   [Vixie]

NXT             30 Next Domain - OBSOLETE                 [RFC2535, RFC3755]

EID             31 Endpoint Identifier                    [Patton]

NIMLOC          32 Nimrod Locator                         [Patton]

SRV             33 Server Selection                       [RFC2782]

ATMA            34 ATM Address                            [Dobrowski]

NAPTR           35 Naming Authority Pointer               [RFC2168, RFC2915]

KX              36 Key Exchanger                          [RFC2230]

CERT            37 CERT                                   [RFC2538]

A6              38 A6                                     [RFC2874]

DNAME           39 DNAME                                  [RFC2672]

SINK            40 SINK                                   [Eastlake]

OPT             41 OPT                                    [RFC2671]

APL             42 APL                                    [RFC3123]

DS              43 Delegation Signer                      [RFC3658]

SSHFP           44 SSH Key Fingerprint                    [RFC-ietf-secsh-dns-05.txt]
IPSECKEY        45 IPSECKEY                               [RFC4025]
RRSIG           46 RRSIG                                  [RFC3755]
NSEC            47 NSEC                                   [RFC3755]
DNSKEY          48 DNSKEY                                 [RFC3755]

SPF             99                                        [RFC-schlitt-spf-classic-02.txt]
UINFO           100                                       [IANA-Reserved]
UID             101                                       [IANA-Reserved]
GID             102                                       [IANA-Reserved]
UNSPEC          103                                       [IANA-Reserved]

TKEY            249 Transaction Key                       [RFC2930]
TSIG            250 Transaction Signature                 [RFC2845]
IXFR            251 incremental transfer                  [RFC1995]
AXFR            252 transfer of an entire zone            [RFC1035]
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]