DNS Record Type Reference

Look up a DNS record type and get its purpose, syntax, and a working example. A, AAAA, CNAME, MX, TXT, SRV, CAA, NS, SOA, PTR — each entry shows what it points at, what the value field looks like, and one or two real-world uses.

Keep it open while writing zone files, debugging mail delivery, or untangling why a CDN handover broke a website. The examples use bind-style syntax, which most providers accept or trivially translate from.

The entries flag common gotchas — CNAME at the apex, TXT length limits, MX priority semantics — where they actually trip people up.

DNS records are typed key-value pairs in a zone file. Each entry has a name, a TTL, a class (almost always IN), a type, and one or more values. The tool's lookup is keyed on type — pick A, AAAA, MX, etc., and you get the canonical structure plus an example zone file line. The values shown match what RFC 1035 and its successor RFCs specify, written out in the bind-style notation that virtually every authoritative DNS provider accepts.

Worked example. You're setting up email on yourdomain.com using a hosted provider. You need three records:

yourdomain.com. 3600 IN MX 10 mail.provider.com. yourdomain.com. 3600 IN TXT "v=spf1 include:provider.com ~all" default._domainkey.yourdomain.com. 3600 IN TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkq…"

The MX priority (10) only matters if you have multiple MX records — lower wins. The SPF TXT record at the apex authorizes the provider's IPs to send mail for your domain. The DKIM record at default._domainkey lets receivers verify cryptographic signatures on outbound mail. Skip any of these and your mail starts getting flagged or dropped.

The gotchas the reference flags: CNAME at the apex (the root of your zone — yourdomain.com without a subdomain) is forbidden by RFC, even though some providers offer "ALIAS" or "ANAME" workarounds. TXT records longer than 255 characters must be split into multiple quoted strings on the same line. MX values must be hostnames, never IP addresses. SRV records have a specific priority/weight/port/target tuple that needs all four fields. PTR records (reverse DNS) live in a separate zone (in-addr.arpa for IPv4, ip6.arpa for IPv6) — your forward DNS provider doesn't always control them.

The ordering of CAA records matters for cert issuance: an explicit CAA permits only the named CA, and "issue ";"" forbids any CA from issuing. If your CA is missing from the CAA record, certificate issuance fails — even with valid domain control proof. Most outages traced to "the new CAA broke our cert renewal" come from one extra trailing record nobody remembered to update.