Apex domains cannot have CNAME records.
Question and response
Question
dig demochimp.com. NS
Answer
demochimp.com. 5 NS ns-1795.awsdns-32.co.uk.
demochimp.com. 5 NS ns-516.awsdns-00.net.
demochimp.com. 5 NS ns-502.awsdns-62.com.
demochimp.com. 5 NS ns-1172.awsdns-18.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0