Apex domains cannot have CNAME records.
Question and response
Question
dig yentavira.com. NS
Answer
yentavira.com. 5 NS ns-1927.awsdns-48.co.uk.
yentavira.com. 5 NS ns-225.awsdns-28.com.
yentavira.com. 5 NS ns-821.awsdns-38.net.
yentavira.com. 5 NS ns-1274.awsdns-31.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0