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.

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

SIG : Signature (RFC 2535)
Signature record used in SIG(0) (RFC 2931). Until RFC 3755 was published, the SIG record was part of DNSSEC; now RRSIG is used for that.

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

A : address record (RFC 1035)
Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host, but also used for DNSBLs, storing subnet masks in RFC 1101, etc.

* : All cached records (RFC 1035)
Returns all records of all types known to the name server. If the name server does not have any information on the name, the request will be forwarded on. The records returned may not be complete. For example, if there is both an A and an MX for a name, but the name server has only the A record cached, only the A record will be returned.

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

NAPTR : Naming Authority Pointer (RFC 3403)
Allows regular expression based rewriting of domain names which can then be used as URIs, further domain names to lookups, etc.

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

DLV : DNSSEC Lookaside Validation record (RFC 4431)
For publishing DNSSEC trust anchors outside of the DNS delegation chain. Uses the same format as the DS record. RFC 5074 describes a way of using these records.

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

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

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

NS : name server record (RFC 1035)
Delegates a DNS zone to use the given authoritative name servers

AAAA : IPv6 address record (RFC 3596)
Returns a 128-bit IPv6 address, most commonly used to map hostnames to an IP address of the host.

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.

DS : Delegation signer (RFC 4034)
The record used to identify the DNSSEC signing key of a delegated zone

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