Apex domains cannot have CNAME records.
Question and response
Question
dig chezaubert.net.dkim.fmhosted.com. NS
Answer
chezaubert.net.dkim.fmhosted.com. 5 NS ns2.messagingengine.com.
chezaubert.net.dkim.fmhosted.com. 5 NS ns1.messagingengine.com.
Authority
The response has no authority records.
Additional
ns1.messagingengine.com. 5 A 162.159.24.178
ns2.messagingengine.com. 5 A 162.159.25.191
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0