Glossary
DNS
TXT record
A general-purpose text record. Because it has no fixed meaning, it became the carrier for SPF, DKIM, DMARC, domain verification and much else — each distinguished only by name and by a version prefix.
Defined in RFC 1035 §3.3.14.
Where this appears
The lessons that use this term, and what each is for.
Email Authentication FundamentalsHow DNS decides where mail goesRead a domain’s MX records and predict the order a sender will try them in.Email Authentication FundamentalsThe shape of an SPF recordFind a domain’s SPF record and break it into its terms.Advanced Email TrustThree pieces, three failure pointsName every component an MTA-STS deployment needs and what happens when each is missing.Advanced Email TrustWhat TLS-RPT reportsSay which of your transport problems the reports will show and which they will not.Domain Security FundamentalsThe records worth knowing, field by fieldRead a zone’s SOA, NS, A, CNAME, MX, TXT and CAA records and say what each asserts.