Apex domains cannot have CNAME records.
Question and response
Question
dig ng. NS
Answer
ng. 5 NS ns5.nic.net.ng.
ng. 5 NS nsa.nic.net.ng.
ng. 5 NS ns3.nic.net.ng.
ng. 5 NS ns4.nic.net.ng.
ng. 5 NS ns2.nic.net.ng.
Authority
The response has no authority records.
Additional
ns2.nic.net.ng. 41668 A 204.61.216.40
ns3.nic.net.ng. 153586 A 185.38.108.108
ns4.nic.net.ng. 153586 A 185.28.194.194
ns5.nic.net.ng. 41668 A 196.216.168.41
nsa.nic.net.ng. 153586 A 41.222.79.3
ns2.nic.net.ng. 41668 AAAA 2001:500:14:6040:ad:0:0:1
ns3.nic.net.ng. 153586 AAAA 2a00:fea0:dead:0:0:0:0:beef
ns5.nic.net.ng. 41668 AAAA 2001:43f8:120:0:0:0:0:41
nsa.nic.net.ng. 153586 AAAA 2c0f:f098:0:0:0:0:0:3
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0