Apex domains cannot have CNAME records.
Question and response
Question
dig ubivox.com. NS
Answer
ubivox.com. 5 NS ns2.curanet.dk.
ubivox.com. 5 NS ns1.curanet.dk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0