Apex domains cannot have CNAME records.
Question and response
Question
dig carmamail.com. NS
Answer
carmamail.com. 5 NS ns-1223.awsdns-24.org.
carmamail.com. 5 NS ns-932.awsdns-52.net.
carmamail.com. 5 NS ns-230.awsdns-28.com.
carmamail.com. 5 NS ns-1832.awsdns-37.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0