Apex domains cannot have CNAME records.
Question and response
Question
dig eduroam.no. NS
Answer
eduroam.no. 3 NS ns.uninett.no.
eduroam.no. 3 NS nac.no.
eduroam.no. 3 NS nn.uninett.no.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0