Apex domains cannot have CNAME records.
Question and response
Question
dig bitcovoice.com. NS
Answer
bitcovoice.com. 2 NS ns-439.awsdns-54.com.
bitcovoice.com. 2 NS ns-1146.awsdns-15.org.
bitcovoice.com. 2 NS ns-926.awsdns-51.net.
bitcovoice.com. 2 NS ns-1958.awsdns-52.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0