Apex domains cannot have CNAME records.
Question and response
Question
dig zml0.com. NS
Answer
zml0.com. 5 NS a2-66.akam.net.
zml0.com. 5 NS a13-64.akam.net.
zml0.com. 5 NS a1-186.akam.net.
zml0.com. 5 NS a12-67.akam.net.
zml0.com. 5 NS a9-67.akam.net.
zml0.com. 5 NS a18-65.akam.net.
Authority
The response has no authority records.
Additional
a12-67.akam.net. 5 A 184.26.160.67
a12-67.akam.net. 5 AAAA 2600:1480:f000:0:0:0:0:43
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0