mailav.fmt1.ntfo.org has no CNAME records.
Question and response
Question
dig mailav.fmt1.ntfo.org. NS
Answer
The response has no answer records.
Authority
fmt1.ntfo.org. 5689 SOA ntfo.org. postmaster.ntfo.org. 2026011700 86400 14400 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0