DHCID : DHCP identifier (RFC 4701)
Used in conjunction with the FQDN option to DHCP

AFSDB : AFS database record (RFC 1183)
Location of database servers of an AFS cell. This record is commonly used by AFS clients to contact AFS cells outside their local domain. A subtype of this record is used by the obsolete DCE/DFS file system.

SRV : Service locator (RFC 2782)
Generalized service location record, used for newer protocols instead of creating protocol-specific records such as MX.

SPF : SPF record (RFC 4408)
Specified as part of the SPF protocol, as an alternative to storing SPF data in TXT records. Uses the same format as the TXT record.

AXFR : Full Zone Transfer (RFC 1035)
Transfer entire zone file from the master name server to secondary name servers.

TXT : Text record (RFC 1035)
Originally for arbitrary human-readable text in a DNS record. Since the early 1990s, however, this record more often carries machine-readable data, such as specified by RFC 1464, opportunistic encryption, Sender Policy Framework, DomainKeys, DNS-SD, etc.

TA : DNSSEC Trust Authorities (None)
Part of a deployment proposal for DNSSEC without a signed DNS root. See the IANA database and Weiler Spec] for details. Uses the same format as the DS record.

SOA : start of authority record (RFC 1035)
Specifies authoritative information about a DNS zone, including the primary name server, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the zone.

NSEC3PARAM : NSEC3 parameters (RFC 5155)
Parameter record for use with NSEC3

RRSIG : DNSSEC signature (RFC 4034)
Signature for a DNSSEC-secured record set. Uses the same format as the SIG record.

MX : mail exchange record (RFC 1035)
Maps a domain name to a list of mail exchange servers for that domain

PTR : pointer record (RFC 1035)
Pointer to a canonical name. Unlike a CNAME, DNS processing does NOT proceed, just the name is returned. The most common use is for implementing reverse DNS lookups, but other uses include such things as DNS-SD.

KEY : Key record (RFC 4034)
Used only for TKEY (RFC 2930). Before RFC 3755 was published, this was also used for DNSSEC, but DNSSEC now uses DNSKEY.

LOC : Location record (RFC 1876)
Specifies a geographical location associated with a domain name

IXFR : Incremental Zone Transfer (RFC 1995)
Requests a zone transfer of the given zone but only differences from a previous serial number. This request may be ignored and a full (AXFR) sent in response if the authoritative server is unable to fulfill the request due to configuration or lack of required deltas.

CERT : Certificate record (RFC 4398)
Stores PKIX, SPKI, PGP, etc.

DNSKEY : DNS Key record (RFC 4034)
The key record used in DNSSEC. Uses the same format as the KEY record.

DNAME : delegation name (RFC 2672)
DNAME will delegate an entire portion of the DNS tree under a new name. In contrast, the CNAME record creates an alias of a single name. Like the CNAME record, the DNS lookup will continue by retrying the lookup with the new name.