Apex domains cannot have CNAME records.
Question and response
Question
dig messagingengine.com. NS
Answer
messagingengine.com. 1 NS fmns1.messagingengine.com.
messagingengine.com. 1 NS fmns2.messagingengine.com.
Authority
The response has no authority records.
Additional
fmns1.messagingengine.com. 1 A 162.159.24.253
fmns2.messagingengine.com. 1 A 162.159.25.114
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0