TXT

networking

Stands for: Text record

A general-purpose DNS record holding free-form text.

A Text record (RFC 1035) stores arbitrary strings, which is why so many verification and email-authentication mechanisms - SPF, DKIM, domain ownership proofs - live in TXT records.

A TXT record holds arbitrary text, which made it the place the internet put everything DNS was never designed to carry. SPF, DKIM, DMARC, domain ownership verification for dozens of services, and ACME challenge tokens all live in TXT records, which is why a busy zone accumulates strings nobody remembers adding.

That accumulation is the practical problem. Verification tokens from services long since cancelled sit there indefinitely, and because nothing breaks when they linger, nobody removes them. Periodically auditing what each string is for, and deleting the ones that answer nothing, is unglamorous work that prevents the situation where no one dares touch the zone.

The one hard rule worth knowing is that a domain must publish exactly one SPF record. Two SPF strings is a permanent error condition that causes evaluation to fail rather than to merge them, and it is the single most common mail authentication misconfiguration. Multiple mail providers must be combined into one record using include mechanisms, not added as separate lines.

Also known as: txt, TXT record

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