Apex domains cannot have CNAME records.
Question and response
Question
dig cereal4health.com. NS
Answer
cereal4health.com. 4 NS jfbextdns1.genmills.com.
cereal4health.com. 4 NS mgoextdns2.genmills.com.
cereal4health.com. 4 NS mgoextdns1.genmills.com.
Authority
The response has no authority records.
Additional
jfbextdns1.genmills.com. 4 A 146.217.5.189
mgoextdns1.genmills.com. 4 A 146.217.15.254
mgoextdns2.genmills.com. 4 A 146.217.15.253
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0