Apex domains cannot have CNAME records.
Question and response
Question
dig idol-webshop.com. NS
Answer
idol-webshop.com. 4 NS ns-1756.awsdns-27.co.uk.
idol-webshop.com. 4 NS ns-59.awsdns-07.com.
idol-webshop.com. 4 NS ns-524.awsdns-01.net.
idol-webshop.com. 4 NS ns-537.awsdns-03.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0