Apex domains cannot have CNAME records.
Question and response
Question
dig cloudns.NET. NS
Answer
cloudns.net. 2 NS dns7.cloudns.net.
cloudns.net. 2 NS dns2.cloudns.net.
cloudns.net. 2 NS ns2.cloudns.net.
cloudns.net. 2 NS pns64.cloudns.uk.
cloudns.net. 2 NS pns4.cloudns.net.
cloudns.net. 2 NS pns1.cloudns.net.
Authority
The response has no authority records.
Additional
ns2.cloudns.net. 2 A 5.161.86.199
dns2.cloudns.net. 2 A 185.136.97.77
dns7.cloudns.net. 2 A 185.136.98.88
pns1.cloudns.net. 2 A 185.136.96.111
pns4.cloudns.net. 2 A 185.136.99.111
pns64.cloudns.uk. 2 A 45.83.251.16
ns2.cloudns.net. 2 AAAA 2a01:4ff:f0:94da:0:0:0:1
dns2.cloudns.net. 2 AAAA 2a06:fb00:1:0:0:0:2:77
dns7.cloudns.net. 2 AAAA 2a06:fb00:1:0:0:0:3:88
pns1.cloudns.net. 2 AAAA 2a06:fb00:1:0:0:0:1:111
pns4.cloudns.net. 2 AAAA 2a06:fb00:1:0:0:0:4:111
pns64.cloudns.uk. 2 AAAA 2a06:fb00:2:0:0:0:4:16
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0