Apex domains cannot have CNAME records.
Question and response
Question
dig brodgar.net. NS
Answer
brodgar.net. 5 NS ns02.brodgar.eu.
brodgar.net. 5 NS ns04.brodgar.uk.
brodgar.net. 5 NS ns01.brodgar.net.
brodgar.net. 5 NS ns03.brodgar.nl.
Authority
The response has no authority records.
Additional
ns01.brodgar.net. 5 A 185.136.96.66
ns02.brodgar.eu. 5 A 185.136.97.66
ns03.brodgar.nl. 5 A 185.136.98.66
ns04.brodgar.uk. 5 A 185.136.99.66
ns01.brodgar.net. 5 AAAA 2a06:fb00:1:0:0:0:1:66
ns02.brodgar.eu. 5 AAAA 2a06:fb00:1:0:0:0:2:66
ns03.brodgar.nl. 5 AAAA 2a06:fb00:1:0:0:0:3:66
ns04.brodgar.uk. 5 AAAA 2a06:fb00:1:0:0:0:4:66
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0