Apex domains cannot have CNAME records.
Question and response
Question
dig cubers.net. NS
Answer
cubers.net. 5 NS curt.ns.cloudflare.com.
cubers.net. 5 NS lorna.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0