DNS Record Type Reference
A searchable reference to every DNS record type — type code, RFC, RDATA fields, zone-file example and the gotchas.
A
Core addressing & delegation · In active use
- Type code
- 1
- Status
- In active use
- Category
- Core addressing & delegation
- Defined in
- RFC 1035
- What it does
- …
- RDATA fields
- …
- Example zone-file record
- …
- Notes & gotchas
- …
How it works
Every DNS answer is a resource record (RR), and every RR has a numeric type code registered with IANA. This reference lists the record types you actually meet in the wild — A, AAAA, CNAME, MX, TXT, NS, SOA, PTR, SRV, CAA, the DNSSEC set (DNSKEY, DS, RRSIG, NSEC, NSEC3, CDS, CDNSKEY) and the newer SVCB/HTTPS service bindings — plus the meta types used for zone transfers and the obsolete ones you may still trip over in old zone files. For each type you get the IANA type code, the RFC that defines it, what the RDATA fields mean, a copy-and-paste zone-file example and the gotchas that bite people.
Search matches on name, type code, RFC number and purpose, so typing 257 lands
on CAA and typing mail pulls up the mail-related types. A note on names you will
see at DNS providers but not in this list: ALIAS, ANAME and
"CNAME flattening" are vendor features that resolve a hostname at the apex and answer with A
or AAAA records — they are not IANA record types. This whole reference is embedded in the
page and runs on plain JavaScript in your browser: no lookups are performed, no domain you
type is sent anywhere, and the CSV export is generated locally from whatever you have
filtered.
Frequently asked questions
What is the difference between an A record and a CNAME record?
An A record (IANA type 1, RFC 1035) maps a name straight to a 32-bit IPv4 address, so the answer ends there. A CNAME (type 5, RFC 1035) says "this name is an alias — go and look up that other name instead", and the resolver restarts the query at the target. The practical consequences matter: a name that owns a CNAME may own no other record type, so you cannot put a CNAME at the zone apex next to the mandatory SOA and NS records, and you must never point an MX or NS record at a CNAME (RFC 2181 forbids it). That apex restriction is why DNS providers invented non-standard ALIAS and ANAME records and "CNAME flattening" — those are vendor features that resolve the target for you and answer with A or AAAA records; they are not IANA record types. The standards-compliant answer is the HTTPS record (type 65) in AliasMode, which is legal at the apex.
What is the difference between A and AAAA records?
They do the same job for different address families: A (type 1, RFC 1035) carries one 32-bit IPv4 address, and AAAA (type 28, RFC 3596) carries one 128-bit IPv6 address. The name is read "quad-A" because the address is four times the size. Publishing both for the same hostname is what makes a host dual-stack — a modern client using Happy Eyeballs (RFC 8305) requests A and AAAA in parallel, races the connections and keeps whichever completes first. The one thing to avoid is a stale or unreachable AAAA record: clients that prefer IPv6 will try it, stall, and only then fall back, so a broken AAAA is measurably worse for users than publishing no AAAA at all. Remove it rather than leaving it dark.
Which DNS record types do I actually need for a normal domain?
A minimal working domain needs an SOA (type 6) and at least two NS records (type 2) at the apex — your DNS provider creates those — plus A and/or AAAA records for the hostnames you serve, and a CNAME for any alias like www. If the domain sends or receives email, add MX records (type 15, lower preference tried first) and TXT records (type 16) holding your SPF, DKIM and DMARC policies; if it does not send mail, publish a null MX (a single MX with target ".", RFC 7505) and an SPF of "v=spf1 -all" to stop spoofing. Then add a CAA record (type 257, RFC 8659) naming the certificate authorities allowed to issue for you — public CAs are required to check it. Everything else on this page is situational: SRV and SVCB/HTTPS for service discovery, PTR for reverse DNS, and the DNSSEC set (DNSKEY, DS, RRSIG, NSEC/NSEC3, CDS, CDNSKEY) if you sign your zone.