Apex domains cannot have CNAME records.
Question and response
Question
dig nac.no. NS
Answer
nac.no. 5 NS nac.no.
nac.no. 5 NS nn.uninett.no.
nac.no. 5 NS biff.uninett.no.
Authority
The response has no authority records.
Additional
nn.uninett.no. 5 A 158.38.0.181
nac.no. 5 A 128.39.2.22
nn.uninett.no. 5 AAAA 2001:700:0:503:0:0:aa:5302
nac.no. 5 AAAA 2001:700:0:102:0:0:0:aa53
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0