Apex domains cannot have CNAME records.
Question and response
Question
dig pubnix.net. NS
Answer
pubnix.net. 5 NS ns1.pubnix.net.
pubnix.net. 5 NS ns2.pubnix.net.
Authority
The response has no authority records.
Additional
ns1.pubnix.net. 5 A 192.172.250.4
ns2.pubnix.net. 5 A 192.172.250.8
ns1.pubnix.net. 5 AAAA 2607:2a00:2:0:0:0:c0ac:fa04
ns2.pubnix.net. 5 AAAA 2607:2a00:2:0:0:0:c0ac:fa08
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0