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

NSEC : Next-Secure record (RFC 4034)
Part of DNSSEC—used to prove a name does not exist. Uses the same format as the (obsolete) NXT record.

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

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.

IPSECKEY : IPSEC Key (RFC 4025)
Key record that can be used with IPSEC

CNAME : Canonical name record (RFC 1035)
Alias of one name to another: the DNS lookup will continue by retrying the lookup with the new name.

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

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

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

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.

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

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

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

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

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.

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