Apex domains cannot have CNAME records.
Question and response
Question
dig 1-grid-mx04.com. NS
Answer
1-grid-mx04.com. 4 NS ns2.dnsbycomodo.net.
1-grid-mx04.com. 4 NS ns4.dnsbycomodo.net.
1-grid-mx04.com. 4 NS ns1.dnsbycomodo.net.
1-grid-mx04.com. 4 NS ns3.dnsbycomodo.net.
Authority
The response has no authority records.
Additional
ns1.dnsbycomodo.net. 4 A 199.167.66.21
ns2.dnsbycomodo.net. 4 A 199.167.66.22
ns3.dnsbycomodo.net. 4 A 104.37.178.1
ns4.dnsbycomodo.net. 4 A 104.37.178.2
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0