Apex domains cannot have CNAME records.
Question and response
Question
dig cybertrust.com. NS
Answer
cybertrust.com. 5 NS auth-ns1.verizonbusiness.com.
cybertrust.com. 5 NS auth-ns2.verizonbusiness.com.
Authority
The response has no authority records.
Additional
auth-ns1.verizonbusiness.com. 5 A 199.249.19.10
auth-ns2.verizonbusiness.com. 5 A 199.249.18.65
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0