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

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

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

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

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.

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.

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

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

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.

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

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

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.

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.

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.

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.

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.

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

SSHFP : SSH Public Key Fingerprint (RFC 4255)
Resource record for publishing SSH public host key fingerprints in the DNS System, in order to aid in verifying the authenticity of the host.