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

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

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

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.

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

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

HIP : Host Identity Protocol (RFC 5205)
Method of separating the end-point identifier and locator roles of IP addresses.

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.

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

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

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

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.

OPT : Option (RFC 2671)
This is a 'pseudo DNS record type' needed to support EDNS

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.

TSIG : Transaction Signature (RFC 2845)
Record that supports one set of security mechanisms for DNS. Used to secure communication between DNS resolvers and Name servers, in contrast to DNSSEC, which secures the actual DNS records from the authoritative name server.

TKEY : Transaction Key (RFC 2930)
One way of providing a key to be used with TSIG

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.

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