dns4.cfu.net has no CNAME records.
Question and response
Question
dig dns4.cfu.net. NS
Answer
The response has no answer records.
Authority
cfu.net. 210 SOA dns-master.cfu.net. domain-manager.cfu.net. 2026022001 36000 1800 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0