Apex domains cannot have CNAME records.
Question and response
Question
dig pingedin.com. NS
Answer
pingedin.com. 5 NS ns-1858.awsdns-40.co.uk.
pingedin.com. 5 NS ns-871.awsdns-44.net.
pingedin.com. 5 NS ns-214.awsdns-26.com.
pingedin.com. 5 NS ns-1326.awsdns-37.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0