mailsql-rw.fmt1.ntfo.org has no CNAME records.
Question and response
Question
dig mailsql-rw.fmt1.ntfo.org. NS
Answer
The response has no answer records.
Authority
fmt1.ntfo.org. 9542 SOA ntfo.org. postmaster.ntfo.org. 2026011700 86400 14400 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0