mail.keff.org has no CNAME records.
Question and response
Question
dig mail.keff.org. NS
Answer
The response has no answer records.
Authority
keff.org. 4425 SOA ns1.he.net. hostmaster.he.net. 2026030200 10800 1800 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0