Apex domains cannot have CNAME records.
Question and response
Question
dig cpgzone.com. NS
Answer
cpgzone.com. 5 NS jfbextdns1.genmills.com.
cpgzone.com. 5 NS mgoextdns1.genmills.com.
cpgzone.com. 5 NS mgoextdns2.genmills.com.
Authority
The response has no authority records.
Additional
jfbextdns1.genmills.com. 5 A 146.217.5.189
mgoextdns1.genmills.com. 5 A 146.217.15.254
mgoextdns2.genmills.com. 5 A 146.217.15.253
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0