Apex domains cannot have CNAME records.
Question and response
Question
dig sim-plymade.com. NS
Answer
sim-plymade.com. 5 NS ns-1563.awsdns-03.co.uk.
sim-plymade.com. 5 NS ns-207.awsdns-25.com.
sim-plymade.com. 5 NS ns-433.awsdns-54.com.
sim-plymade.com. 5 NS ns-594.awsdns-10.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0