Apex domains cannot have CNAME records.
Question and response
Question
dig nameshift.com. NS
Answer
nameshift.com. 5 NS ns-909.awsdns-49.net.
nameshift.com. 5 NS ns-1044.awsdns-02.org.
nameshift.com. 5 NS ns-1745.awsdns-26.co.uk.
nameshift.com. 5 NS ns-347.awsdns-43.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0