Apex domains cannot have CNAME records.
Question and response
Question
dig providerbox.net. NS
Answer
providerbox.net. 5 NS ns2.providerbox.de.
providerbox.net. 5 NS ns.providerbox.de.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0