Apex domains cannot have CNAME records.
Question and response
Question
dig zuppler.com. NS
Answer
zuppler.com. 5 NS ns-454.awsdns-56.com.
zuppler.com. 5 NS ns-1661.awsdns-15.co.uk.
zuppler.com. 5 NS ns-1369.awsdns-43.org.
zuppler.com. 5 NS ns-643.awsdns-16.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0