Apex domains cannot have CNAME records.
Question and response
Question
dig grluk.com. NS
Answer
grluk.com. 5 NS ns-1199.awsdns-21.org.
grluk.com. 5 NS ns-165.awsdns-20.com.
grluk.com. 5 NS ns-422.awsdns-52.com.
grluk.com. 5 NS ns-1359.awsdns-41.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0