Apex domains cannot have CNAME records.
Question and response
Question
dig examsoft.com. NS
Answer
examsoft.com. 5 NS ns-757.awsdns-30.net.
examsoft.com. 5 NS ns-1943.awsdns-50.co.uk.
examsoft.com. 5 NS ns-246.awsdns-30.com.
examsoft.com. 5 NS ns-1493.awsdns-58.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0