Apex domains cannot have CNAME records.
Question and response
Question
dig cfu.net. NS
Answer
cfu.net. 5 NS dns2.cfu.net.
cfu.net. 5 NS dns.cfu.net.
cfu.net. 5 NS dns3.cfu.net.
cfu.net. 5 NS dns4.cfu.net.
cfu.net. 5 NS dns1.cfu.net.
Authority
The response has no authority records.
Additional
dns.cfu.net. 5 A 24.149.0.24
dns1.cfu.net. 5 A 24.149.0.6
dns2.cfu.net. 5 A 24.149.0.7
dns3.cfu.net. 5 A 69.57.207.193
dns4.cfu.net. 5 A 24.149.0.21
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0