DNS Record Types

Every DNS record has a type that defines what the content of the record means. For example, a DNS record of type MX contains the location of a mail exchange server. So when you want to know the mail server of some email address, you can perform a DNS lookup that queries the MX records.

All the record types are strictly defined in so-called RFCs (request for comments). Since the beginning of the domain name system, a lot of new record types have been added. Some record types have also been declared obsolete, because they have been replaced by a newer record type.

There are many different types of DNS record in existence. Most of them are used only occasionally. Only a couple record types are used very frequently.

Common DNS Record Types

Some of the most commonly used DNS record types are:

A Record

Maps a domain name to an IPv4 address. This is the most basic and common type of DNS record, used to point a domain or subdomain to an IP address.

AAAA Record

Similar to an A record, but maps a domain name to an IPv6 address instead of an IPv4 address.

CNAME Record

Canonical Name record that maps an alias name to a true or canonical domain name. For example, www.example.com might be a CNAME for example.com.

MX Record

Mail Exchange record specifies the mail servers responsible for accepting email on behalf of a domain and their priority.

NS Record

Name Server record delegates a DNS zone to use the given authoritative name servers. These records identify which servers are responsible for a zone.

TXT Record

Text record that contains arbitrary text data. Often used for domain verification, SPF, DKIM, and DMARC records for email security.

SOA Record

Start of Authority record contains administrative information about the DNS zone, including the primary name server, the email address of the domain administrator, and various refresh timers.

All DNS Record Types

Here is a comprehensive list of all DNS record types currently in use:

A

IPv4 address

AAAA

IPv6 address

AFSDB

AFS database location

APL

Address prefix list

AXFR

Authoritative zone transfer

CAA

Certification authority authorization

CDNSKEY

Child copy of a DNSKEY

CDS

Child copy of DS

CERT

Cryptographic certificate

CNAME

Canonical name

CSYNC

Child-to-parent synchronization

DHCID

DHCP identifier

DLV

DNSSEC lookaside validation

DNAME

Delegation name

DNSKEY

Cryptographic key for DNSSEC

DS

Delegation signer

EUI48

MAC address (EUI-48)

EUI64

MAC address (EUI-64)

HINFO

Host information

HIP

Host identification protocol

HTTPS

HTTPS binding

IPSECKEY

Cryptographic key for IPsec

IXFR

Incremental zone transfer

KEY

Cryptographic key for DNSSEC (obsoleted by DNSKEY)

KX

Key exchange

LOC

Geographical location

MX

Mail exchange

NAPTR

Naming authority pointer

NS

Name server

NSEC3

Next secure (version 3)

NSEC3PARAM

Parameter for NSEC3

NSEC

Next secure (obsoleted by NSEC3)

NXT

DNSSEC key (obsoleted by NSEC)

OPENPGPKEY

Public key for OpenPGP

OPT

EDNS option

PTR

Canonical name pointer

RP

Responsible person

RRSIG

Resource record signature for DNSSEC

SIG

Resource record signature for DNSSEC (obsoleted by RRSIG)

SMIMEA

S/MIME association

SOA

Start of authority

SSHFP

Public key fingerprint for SSH

SVCB

Service binding

SRV

Service locator

TA

Trust authority for DNSSEC

TKEY

Transaction key

TLSA

Certificate association for TLS

TSIG

Transaction signature

TXT

Human-readable text

URI

Uniform resource identifier

ZONEMD

Message digest for DNS zones

DNS Record Types in Practice

While there are many DNS record types, most domain administrators will primarily work with a small subset:

Website Hosting: A, AAAA, and CNAME records to point domains to web servers
Email Configuration: MX records for mail delivery, along with TXT records for SPF, DKIM, and DMARC
Domain Management: NS and SOA records for DNS infrastructure
Service Discovery: SRV records for specific services like VoIP or chat protocols

RFC Standards

DNS record types are defined in various RFC (Request for Comments) documents, which are the official specifications for Internet protocols. For example:

RFC 1035 defines the basic record types (A, NS, CNAME, MX, etc.)
RFC 3596 defines the AAAA record for IPv6 addresses
RFC 7208 defines the SPF record (now implemented as TXT)
RFC 6698 defines the TLSA record for DANE

Obsolete Record Types

Some DNS record types have been declared obsolete and replaced by newer types:

KEY has been obsoleted by DNSKEY for DNSSEC
NXT has been obsoleted by NSEC
NSEC has been largely replaced by NSEC3
SIG has been obsoleted by RRSIG

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