Apex domains cannot have CNAME records.
Question and response
Question
dig glowingblue.com. NS
Answer
glowingblue.com. 5 NS ans02.89grad.ch.
glowingblue.com. 5 NS ans03.89grad.ch.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0