Apex domains cannot have CNAME records.
Question and response
Question
dig nxorg.org. NS
Answer
nxorg.org. 5 NS ns-644.awsdns-16.net.
nxorg.org. 5 NS ns-1946.awsdns-51.co.uk.
nxorg.org. 5 NS ns-550.awsdns-04.net.
nxorg.org. 5 NS ns-1359.awsdns-41.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0