The TXT record
The TXT (text) record holds arbitrary ASCII text.
Rather than forming part of the Internet’s infrastructure,
TXT records are used by applications that run atop it, as a way to make short pieces of data available to the public.
A common use case is to prove that a domain belongs to a particular party, as only somebody in control of the domain can set records on it:
- When delivering e-mail, Sender Policy Framework and DomainKeys Identified Mail both rely on
TXTrecords for a domain, to ensure a message comes from that domain and has not been tampered with.
- The Let’s Encrypt DNS-01 challenge issues TLS certificates for a domain by demanding that a particular
TXTrecord is set, and uses the existence of the record as proof that the domain is being controlled by the same person or script requesting a certificate.
Here, we query for
TXT records of the domain
The result is a record containing an old Computer Science proverb.
$ dog TXT txt-example.lookup.dog TXT txt-example.lookup.dog. 1h00m00s "Cache Invalidation and Naming Things"