Apex domains cannot have CNAME records.
Question and response
Question
dig global.clara.net. NS
Answer
global.clara.net. 2 NS gns2.cdn.eu.clara.net.
global.clara.net. 2 NS gns1.cdn.eu.clara.net.
global.clara.net. 2 NS gns3.cdn.eu.clara.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0