List of DNS record types
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This is an overview of resource records (RRs) permissible in zone files of the Domain Name System (DNS). It also contains pseudo-RRs.
Resource records
| Type | Type id (decimal) | Defining RFC | Description | Function |
|---|---|---|---|---|
| A | 1 | RFC | Address record | Returns a 32-bit IPv4 address, most commonly used to map hostnames to an IP address of the host, but it is also used for DNSBLs, storing subnet masks, etc. |
| AAAA | 28 | RFC | IPv6 address record | Returns a 128-bit IPv6 address, most commonly used to map hostnames to an IP address of the host. |
| AFSDB | 18 | RFC | AFS database record | 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. |
| APL | 42 | RFC | Address Prefix List | Specify lists of address ranges, e.g. in CIDR format, for various address families. Experimental. |
| CAA | 257 | RFC | Certification Authority Authorization | DNS Certification Authority Authorization, constraining acceptable CAs for a host/domain |
| CDNSKEY | 60 | RFC | Child copy of DNSKEY record, for transfer to parent | |
| CDS | 59 | RFC | Child DS | Child copy of DS record, for transfer to parent |
| CERT | 37 | RFC | Certificate record | Stores digital certificates in various forms (PKIX, SPKI, PGP, etc). |
| CNAME | 5 | RFC | Canonical name record | Alias of one name to another: the DNS lookup will continue by retrying the lookup with the new name. |
| CSYNC | 62 | RFC 7477 | Child-to-Parent Synchronization | Specify a synchronization mechanism between a child and a parent DNS zone. Typical example is declaring the same NS records in the parent and the child zone |
| DHCID | 49 | RFC 4701 | DHCP identifier | Used in conjunction with the FQDN option to DHCP |
| DLV | 32769 | RFC 4431 | DNSSEC Lookaside Validation record | 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. |
| DNAME | 39 | RFC 6672 | Delegation name record | Alias for a name and all its subnames, unlike CNAME, which is an alias for only the exact name. Like a CNAME record, the DNS lookup will continue by retrying the lookup with the new name. |
| DNSKEY | 48 | RFC | DNS Key record | The key record used in DNSSEC. Uses the same format as the KEY record. |
| DS | 43 | RFC | Delegation signer | The record used to identify the DNSSEC signing key of a delegated zone |
| EUI48 | 108 | RFC 7043 | MAC address (EUI-48) | A 48-bit IEEE Extended Unique Identifier. |
| EUI64 | 109 | RFC 7043 | MAC address (EUI-64) | A 64-bit IEEE Extended Unique Identifier. |
| HINFO | 13 | RFC RFC | Placeholder record, or host information | Repurposed to be used while responding to ANY queries. Originally defined as "Host information", intended to inform about host's operating system and hardware. RFC 8482 did not obsolete this conventional meaning for explicit HINFO queries, but rather considers it rarely used. |
| HIP | 55 | RFC 8005 | Host Identity Protocol | Method of separating the end-point identifier and locator roles of IP addresses. |
| HTTPS | 65 | RFC | HTTPS Binding | A specialised type of SVCB record. Provides connection information required to establish a secure connection via HTTPS, which would ordinarily be obtained and negotiated during connection to the host. Obtaining the information from the DNS server instead of negotiating it with the host allows for more secure connections (e.g. by using Encrypted Client Hello) and lower latency when the connection to the host is first established. |
| IPSECKEY | 45 | RFC 4025 | IPsec Key | Key record that can be used with IPsec |
| KEY | 25 | RFC 2535 RFC 2930 | Key record | Used only for SIG(0) (RFC 2931) and TKEY (RFC 2930). RFC 3445 eliminated their use for application keys and limited their use to DNSSEC. RFC 3755 designates DNSKEY as the replacement within DNSSEC. RFC 4025 designates IPSECKEY as the replacement for use with IPsec. |
| KX | 36 | RFC 2230 | Key Exchanger record | Used with some cryptographic systems (not including DNSSEC) to identify a key management agent for the associated domain-name. Note that this has nothing to do with DNS Security. It is Informational status, rather than being on the IETF standards-track. It has always had limited deployment, but is still in use. |
| LOC | 29 | RFC 1876 | Location record | Specifies a geographical location associated with a domain name |
| MX | 15 | RFC RFC 7505 | Mail exchange record | List of mail exchange servers that accept email for a domain |
| NAPTR | 35 | RFC 3403 | Naming Authority Pointer | Allows regular-expression-based rewriting of domain names which can then be used as URIs, further domain names to lookups, etc. |
| NS | 2 | RFC | Name server record | Delegates a DNS zone to use the given authoritative name servers |
| NSEC | 47 | RFC | Next Secure record | Part of DNSSEC—used to prove a name does not exist. Uses the same format as the (obsolete) NXT record. |
| NSEC3 | 50 | RFC 5155 | Next Secure record version 3 | An extension to DNSSEC that allows proof of nonexistence for a name without permitting zonewalking |
| NSEC3PARAM | 51 | RFC 5155 | NSEC3 parameters | Parameter record for use with NSEC3 |
| OPENPGPKEY | 61 | RFC 7929 | OpenPGP public key record | A DNS-based Authentication of Named Entities (DANE) method for publishing and locating OpenPGP public keys in DNS for a specific email address using an OPENPGPKEY DNS resource record. |
| PTR | 12 | RFC | PTR Resource Record[de] | Pointer to a canonical name. Unlike a CNAME, DNS processing stops and just the name is returned. The most common use is for implementing reverse DNS lookups, but other uses include such things as DNS-SD. |
| RP | 17 | RFC | Responsible Person | Information about the responsible person(s) for the domain. Usually an email address with the @ replaced by a . |
| RRSIG | 46 | RFC | DNSSEC signature | Signature for a DNSSEC-secured record set. Uses the same format as the SIG record. |
| SIG | 24 | RFC 2535 | Signature | Signature record used in SIG(0) (RFC 2931) and TKEY (RFC 2930). RFC 3755 designated RRSIG as the replacement for SIG for use within DNSSEC. |
| SMIMEA | 53 | RFC 8162 | S/MIME cert association | Associates an S/MIME certificate with a domain name for sender authentication. |
| SOA | 6 | RFC RFC 2308 | Start of [a zone of] authority record | 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. |
| SRV | 33 | RFC 2782 | Service locator | Generalized service location record, used for newer protocols instead of creating protocol-specific records such as MX. |
| SSHFP | 44 | RFC 4255 | SSH Public Key Fingerprint | Resource record for publishing SSH public host key fingerprints in the DNS, in order to aid in verifying the authenticity of the host. RFC 6594 defines ECC SSH keys and SHA-256 hashes. See the for details. |
| SVCB | 64 | RFC | Service Binding | This resource record provides metadata and other information that can help clients connect to the host. The HTTPS record is a specialised SVCB record to help when establishing HTTPS connections. The more general SVCB record can provide other information such as supported protocols, alternative endpoints, and some types of aliasing not supported by CNAME records. |
| TA | 32768 | —N/a | DNSSEC Trust Authorities | Part of a deployment proposal for DNSSEC without a signed DNS root. See the and for details. Uses the same format as the DS record. |
| TKEY | 249 | RFC 2930 | Transaction Key record | A method of providing keying material to be used with TSIG that is encrypted under the public key in an accompanying KEY RR. |
| TLSA | 52 | RFC 6698 | TLSA certificate association | A record for DANE. RFC 6698 defines "The TLSA DNS resource record is used to associate a TLS server certificate or public key with the domain name where the record is found, thus forming a 'TLSA certificate association'". |
| TSIG | 250 | RFC 2845 | Transaction Signature | Can be used to authenticate dynamic updates as coming from an approved client, or to authenticate responses as coming from an approved recursive name server similar to DNSSEC. |
| TXT | 16 | RFC | Text record | 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, DKIM, DMARC, DNS-SD, etc. |
| URI | 256 | RFC 7553 | Uniform Resource Identifier | Can be used for publishing mappings from hostnames to URIs. |
| ZONEMD | 63 | RFC 8976 | Message Digests for DNS Zones | Provides a cryptographic message digest over DNS zone data at rest. |
Other types and pseudo-RRs
Other types of records simply provide some types of information (for example, an HINFO record gives a description of the type of computer/OS a host uses), or others return data used in experimental features. The "type" field is also used in the protocol for various operations.
| Type | Type id. | Defining RFC | Description | Function |
|---|---|---|---|---|
| * | 255 | RFC | All cached records | 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. Usually referred to as ANY (e.g., in dig, Windows nslookup, and Wireshark). In 2019, RFC standards-track publication led many DNS providers, including Cloudflare, to provide only minimal responses to "ANY" queries, instead of enumerating records. |
| AXFR | 252 | RFC | Authoritative Zone Transfer | Transfer entire zone file from the primary name server to secondary name servers. |
| IXFR | 251 | RFC 1996 | Incremental Zone Transfer | 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 | 41 | RFC 6891 | Option | This is a pseudo-record type needed to support EDNS. |
| ALIAS / ANAME / apex CNAME / CNAME flattening / top-level redirection | - | draft-ietf-dnsop-aname-04 | Alias similar to DNAME | An ANAME, ALIAS. apex CNAME, CNAME flattening, or sometimes also top-level redirection record is a pseudo record type is a commonly used but not RFC-standardized record type. Its implementation varies. It serves as an alternative to CNAMEs especially for the bare domain name and where such records should co-exist with others. It causes the DNS software vendor to synthetically generate A and AAAA records similar to the ones of the ANAME-records destination. If the destination changes these synthetic A and AAAA records change automatically as well. The actual mechanisms used are often considered proprietary. |
Obsolete record types
Progress has rendered some of the originally defined record-types obsolete. Of the records listed at IANA, some have limited use, for various reasons. Some are marked obsolete in the list, some are for very obscure services, some are for older versions of services, and some have special notes saying they are "not right".
| Type | Type id. (decimal) | Defining RFC | Obsoleted by | Description |
|---|---|---|---|---|
| MD | 3 | RFC | RFC | Mail destination (MD) and mail forwarder (MF) records; MAILA is not an actual record type, but a query type which returns MF and/or MD records. RFC 973 replaced these records with the MX record. |
| MF | 4 | |||
| MAILA | 254 | |||
| MB | 7 | RFC | Not formally obsoleted. Unlikely to be ever adopted (RFC 2505). | MB, MG, MR, and MINFO are records to publish subscriber mailing lists. MAILB is a query code which returns one of those records. The intent was for MB and MG to replace the SMTP VRFY and EXPN commands. MR was to replace the "551 User Not Local" SMTP error. Later, RFC 2505 recommended that both VRFY and EXPN be disabled, making MB and MG unnecessary. They were classified as experimental by RFC 1035. |
| MG | 8 | |||
| MR | 9 | |||
| MINFO | 14 | |||
| MAILB | 253 | |||
| WKS | 11 | RFC RFC | Declared as "not to be relied upon" by RFC (more in RFC ). | Record to describe well-known services supported by a host. Not used in practice. The current recommendation and practice is to determine whether a service is supported on an IP address by trying to connect to it. SMTP is even prohibited from using WKS records in MX processing. |
| NB | 32 | RFC | Mistakes (from RFC 1002); the numbers are now assigned to NIMLOC and SRV. | |
| NBSTAT | 33 | |||
| NULL | 10 | RFC | RFC | Obsoleted by RFC 1035. RFC 883 defined "completion queries" (opcode 2 and maybe 3) which used this record. RFC 1035 later reassigned opcode 2 to be "status" and reserved opcode 3. |
| A6 | 38 | RFC | RFC | Defined as part of early IPv6 but downgraded to experimental by RFC 3363; later downgraded to historic by RFC 6563. |
| NXT | 30 | RFC 2065 | RFC 3755 | Part of the first version of DNSSEC (RFC 2065). NXT was obsoleted by DNSSEC updates (RFC 3755). At the same time, the domain of applicability for KEY and SIG was also limited to not include DNSSEC use. |
| KEY | 25 | |||
| SIG | 24 | |||
| HINFO | 13 | RFC | Unobsoleted by RFC . Currently used by Cloudflare in response to queries of the type ANY. | Record intended to provide information about host CPU type and operating system. It was intended to allow protocols to optimize processing when communicating with similar peers. |
| RP | 17 | RFC | RP may be used for certain human-readable information regarding a different contact point for a specific host, subnet, or other domain level label separate than that used in the SOA record. | |
| X25 | 19 | Not in current use by any notable application | ||
| ISDN | 20 | Not in current use by any notable application | ||
| RT | 21 | Not in current use by any notable application | ||
| NSAP | 22 | RFC 1706 | Not in current use by any notable application | |
| NSAP-PTR | 23 | Not in current use by any notable application | ||
| PX | 26 | RFC 2163 | Not in current use by any notable application | |
| EID | 31 | —N/a | Defined by the Internet Draft, but never made it to RFC status. Not in current use by any notable application | |
| NIMLOC | 32 | —N/a | ||
| ATMA | 34 | —N/a | Defined by The ATM Forum Committee. | |
| APL | 42 | RFC 3123 | Specify lists of address ranges, e.g. in CIDR format, for various address families. Experimental. | |
| SINK | 40 | —N/a | Defined by the Internet Draft, but never made it to RFC status | |
| GPOS | 27 | RFC 1712 | A more limited early version of the LOC record | |
| UINFO | 100 | —N/a | IANA reserved, no RFC documented them and support was removed from BIND in the early 90s. | |
| UID | 101 | —N/a | ||
| GID | 102 | —N/a | ||
| UNSPEC | 103 | —N/a | ||
| SPF | 99 | RFC 4408 | RFC 7208 | Specified as part of the Sender Policy Framework protocol as an alternative to storing SPF data in TXT records, using the same format. It was discontinued in RFC 7208 due to widespread lack of support. |
| NINFO | 56 | —N/a | Used to provide status information about a zone. Requested for the IETF draft "The Zone Status (ZS) DNS Resource Record" in 2008. Expired without adoption. | |
| RKEY | 57 | —N/a | Used for encryption of NAPTR records. Requested for the IETF draft "The RKEY DNS Resource Record" in 2008. Expired without adoption. | |
| TALINK | 58 | —N/a | Defined by the Internet Draft, but never made it to RFC status | |
| NID | 104 | RFC 6742 | Not in use by any notable application and marked as "experimental" | |
| L32 | 105 | |||
| L64 | 106 | |||
| LP | 107 | |||
| DOA | 259 | —N/a | Defined by the Internet Draft, but never made it to RFC status |
Further reading
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