Apex domains cannot have CNAME records.
Question and response
Question
dig chargify.com. NS
Answer
chargify.com. 5 NS ns-1231.awsdns-25.org.
chargify.com. 5 NS ns-1841.awsdns-38.co.uk.
chargify.com. 5 NS ns-11.awsdns-01.com.
chargify.com. 5 NS ns-974.awsdns-57.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0