Apex domains cannot have CNAME records.
Question and response
Question
dig nordu.net. NS
Answer
nordu.net. 4 NS sunic.sunet.se.
nordu.net. 4 NS backup-server.nordu.net.
nordu.net. 4 NS nn.uninett.no.
nordu.net. 4 NS server.nordu.net.
Authority
The response has no authority records.
Additional
nn.uninett.no. 5 A 158.38.0.181
sunic.sunet.se. 5 A 192.36.125.2
server.nordu.net. 4 A 193.10.252.19
backup-server.nordu.net. 4 A 193.10.252.66
nn.uninett.no. 5 AAAA 2001:700:0:503:0:0:aa:5302
sunic.sunet.se. 5 AAAA 2001:6b0:7:0:0:0:0:2
server.nordu.net. 4 AAAA 2001:948:4:2:0:0:0:19
backup-server.nordu.net. 4 AAAA 2001:948:4:1:0:0:0:66
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0