Apex domains cannot have CNAME records.
Question and response
Question
dig as23951.net. NS
Answer
as23951.net. 5 NS ns-1720.awsdns-23.co.uk.
as23951.net. 5 NS ns-1068.awsdns-05.org.
as23951.net. 5 NS ns-97.awsdns-12.com.
as23951.net. 5 NS ns-634.awsdns-15.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0