Apex domains cannot have CNAME records.
Question and response
Question
dig classicalquantummechanics.org. NS
Answer
classicalquantummechanics.org. 2 NS ns-1044.awsdns-02.org.
classicalquantummechanics.org. 2 NS ns-1934.awsdns-49.co.uk.
classicalquantummechanics.org. 2 NS ns-780.awsdns-33.net.
classicalquantummechanics.org. 2 NS ns-1492.awsdns-58.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0