Apex domains cannot have CNAME records.
Question and response
Question
dig shop. NS
Answer
shop. 5 NS k.gmoregistry.net.
shop. 5 NS a.gmoregistry.net.
shop. 5 NS b.gmoregistry.net.
shop. 5 NS l.gmoregistry.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0