Apex domains cannot have CNAME records.
Question and response
Question
dig persianjoke.org. NS
Answer
persianjoke.org. 5 NS ns-1591.awsdns-06.co.uk.
persianjoke.org. 5 NS ns-1890.awsdns-44.co.uk.
persianjoke.org. 5 NS ns-409.awsdns-51.com.
persianjoke.org. 5 NS ns-922.awsdns-51.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0