ncopenbook.gov has no TXT records.
Question and response
Question
dig ncopenbook.gov. TXT
Answer
The response has no answer records.
Authority
gov. 300 SOA a.ns.gov. dns.cloudflare.com. 1772244301 3600 900 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0