Apex domains cannot have CNAME records.
Question and response
Question
dig concurcompleat.com. NS
Answer
concurcompleat.com. 5 NS ns-1841.awsdns-38.co.uk.
concurcompleat.com. 5 NS ns-241.awsdns-30.com.
concurcompleat.com. 5 NS ns-790.awsdns-34.net.
concurcompleat.com. 5 NS ns-1363.awsdns-42.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0