Apex domains cannot have CNAME records.
Question and response
Question
dig ocom.com. NS
Answer
ocom.com. 1 NS ns5.leaseweb.nl.
ocom.com. 1 NS ns4.leaseweb.net.
ocom.com. 1 NS ns1.leaseweb.nl.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0