Apex domains cannot have CNAME records.
Question and response
Question
dig guitarxperts.com. NS
Answer
guitarxperts.com. 3 NS ns-1960.awsdns-53.co.uk.
guitarxperts.com. 3 NS ns-591.awsdns-09.net.
guitarxperts.com. 3 NS ns-255.awsdns-31.com.
guitarxperts.com. 3 NS ns-1785.awsdns-31.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0