Apex domains cannot have CNAME records.
Question and response
Question
dig muxx.net. NS
Answer
muxx.net. 5 NS ns-1591.awsdns-06.co.uk.
muxx.net. 5 NS ns-1332.awsdns-38.org.
muxx.net. 5 NS ns-75.awsdns-09.com.
muxx.net. 5 NS ns-739.awsdns-28.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0