A DNS zone functions as a distributed database, where every entry is a Resource Record (RR). Each record type is assigned a unique integer Value (Type ID) by IANA and is defined by specific RFC standards.
1. Foundational Records
These records constitute the core routing logic of the domain name system.
| Type | ID | Meaning | Reference |
|---|---|---|---|
| A | 1 | Maps a hostname to a 32-bit IPv4 address. | RFC1035 |
| NS | 2 | Delegates a DNS zone to an authoritative name server. | RFC1035 |
| CNAME | 5 | Canonical Name. Maps an alias hostname to another hostname. | RFC1035 |
| SOA | 6 | Start of Authority. Specifies authoritative information about a DNS zone. | RFC1035 |
| PTR | 12 | Pointer. Maps an IP address back to a hostname (Reverse DNS). | RFC1035 |
| AAAA | 28 | Maps a hostname to a 128-bit IPv6 address. | RFC3596 |
2. Service, Routing & Metadata
Records used for email delivery, service discovery, and arbitrary text data.
| Type | ID | Meaning | Reference |
|---|---|---|---|
| MX | 15 | Mail Exchange. Directs email to a mail server with a priority value. | RFC1035 |
| TXT | 16 | Text strings. Used for SPF, DKIM, DMARC, and site verification. | RFC1035 |
| SRV | 33 | Service Locator. Defines location (hostname/port) of specific services (e.g. SIP). | RFC2782 |
| NAPTR | 35 | Naming Authority Pointer. Used for URN resolution and VoIP/SIP. | RFC3403 |
| URI | 256 | Maps a hostname to a Uniform Resource Identifier (URI). | RFC7553 |
3. Security & Validation (DNSSEC/DANE)
Records specifically designed to validate identity, integrity, and authenticity.
| Type | ID | Meaning | Reference |
|---|---|---|---|
| DS | 43 | Delegation Signer. The chain of trust anchor from parent to child zone. | RFC4034 |
| SSHFP | 44 | SSH Public Key Fingerprint. Publishes SSH host keys in DNS. | RFC4255 |
| RRSIG | 46 | Resource Record Signature. Contains the digital signature for a record set. | RFC4034 |
| NSEC | 47 | Next Secure. Proof of non-existence for a record name. | RFC4034 |
| DNSKEY | 48 | The public key used to verify RRSIG signatures. | RFC4034 |
| NSEC3 | 50 | Hashed version of NSEC to prevent zone enumeration. | RFC5155 |
| TLSA | 52 | TLS Certificate Association. Pin certificates to a domain (DANE). | RFC6698 |
| OPENPGPKEY | 61 | Public key for OpenPGP. | RFC7929 |
| CAA | 257 | Certification Authority Authorization. Restricts which CAs can issue certificates. | RFC8659 |
4. Modern & Emerging Standards
Newer record types focused on performance (binding), privacy, and blockchain/Web3 integration.
| Type | ID | Meaning | Reference |
|---|---|---|---|
| ZONEMD | 63 | Message Digest for DNS Zones. Verifies data integrity for an entire zone. | RFC8976 |
| SVCB | 64 | Service Binding. General-purpose mechanism for service connection params. | RFC9460 |
| HTTPS | 65 | SVCB-compatible record specifically for HTTP(S) bootstrapping (ALPN, ECH). | RFC9460 |
| RESINFO | 261 | Resolver Information. Exposes resolver capabilities as key/value pairs. | RFC9606 |
| WALLET | 262 | Maps a domain to a public wallet address (Web3/Crypto). | Paul_Hoffman |
5. Other Assigned Types
The IANA registry includes many specific or experimental types.
| Type | ID | Purpose | Status/Ref |
|---|---|---|---|
| HINFO | 13 | Host CPU and OS type information. | RFC1035 |
| LOC | 29 | Geographical Location (Lat/Long). | RFC1876 |
| CERT | 37 | Stores certificates (PKIX, SPKI, PGP, etc.). | RFC4398 |
| DNAME | 39 | Delegated Name. Aliases an entire subtree of the domain space. | RFC6672 |
| OPT | 41 | EDNS0 Option pseudo-record. | RFC6891 |
| TKEY | 249 | Transaction Key. | RFC2930 |
| TSIG | 250 | Transaction Signature. | RFC8945 |
| AXFR | 252 | Zone Transfer (Request to transfer entire zone). | RFC1035 |
| MAILB | 253 | Mailbox-related records (MB, MG, MR). | RFC1035 |
| ANY | 255 | A request for all records (wildcard). | RFC1035 |
6. Deprecated or Obsolete
The following types are generally considered obsolete, experimental, or deprecated. Modern resolvers may ignore them.
Values: 3 (MD), 4 (MF), 7 (MB), 8 (MG), 9 (MR), 10 (NULL), 11 (WKS), 14 (MINFO), 17 (RP), 18 (AFSDB), 19 (X25), 20 (ISDN), 21 (RT), 22 (NSAP), 23 (NSAP-PTR), 24 (SIG), 25 (KEY), 26 (PX), 27 (GPOS), 30 (NXT), 31 (EID), 32 (NIMLOC), 34 (ATMA), 36 (KX), 38 (A6), 40 (SINK), 42 (APL), 99 (SPF - use TXT), 254 (MAILA).