Apex domains cannot have CNAME records.
Question and response
Question
dig iranswer.com. NS
Answer
iranswer.com. 5 NS ns-1403.awsdns-47.org.
iranswer.com. 5 NS ns-163.awsdns-20.com.
iranswer.com. 5 NS ns-174.awsdns-21.com.
iranswer.com. 5 NS ns-982.awsdns-58.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0