Apex domains cannot have CNAME records.
Question and response
Question
dig fusixnetworks.net. NS
Answer
fusixnetworks.net. 5 NS ns1.fusixnetworks.net.
fusixnetworks.net. 5 NS ns2.fusixnetworks.eu.
fusixnetworks.net. 5 NS ns0.fusixnetworks.net.
Authority
The response has no authority records.
Additional
ns0.fusixnetworks.net. 5 A 37.139.139.37
ns1.fusixnetworks.net. 5 A 178.249.154.2
ns2.fusixnetworks.eu. 5 A 94.142.240.133
ns0.fusixnetworks.net. 5 AAAA 2a00:a7c0:1000:1:0:0:0:10
ns1.fusixnetworks.net. 5 AAAA 2a02:1668:a2b:1950:0:0:0:2
ns2.fusixnetworks.eu. 5 AAAA 2a02:898:0:20:0:0:1:1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0