Apex domains cannot have CNAME records.
Question and response
Question
dig zbscloud.com. NS
Answer
zbscloud.com. 5 NS zns2.arvid.ee.
zbscloud.com. 5 NS zns1.arvid.ee.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0