DNS Record Types
Last updated:
The records you'll actually touch, in rough order of frequency:
| Record | Maps | Notes |
|---|---|---|
| A | name → IPv4 | The bread and butter |
| AAAA | name → IPv6 | "Quad-A" |
| CNAME | name → another name | No other records may coexist on the name; never at a zone apex |
| MX | domain → mail server name | Priority field: lower = preferred |
| TXT | name → arbitrary text | SPF, DKIM, DMARC, domain verification |
| NS | zone → authoritative servers | Delegation lives here |
| SOA | zone → admin metadata | Serial, refresh/retry, negative-cache TTL |
| PTR | IP → name (reverse DNS) | Lives under in-addr.arpa / ip6.arpa |
| SRV | service → host:port | _service._proto.name; AD, SIP, XMPP |
| CAA | domain → allowed CAs | Which authorities may issue your certs |
Three that cause the most tickets
- CNAME at the apex —
example.com CNAME ...is illegal (the apex needs SOA/NS). Providers work around it with ALIAS/ANAME/flattening. - MX pointing at a CNAME — technically forbidden, breaks some mail servers; point MX at an A/AAAA name.
- Stale SOA serial discipline — secondaries only zone-transfer when the serial increases. Forgot to bump it? Your change exists on one server only.