Apex domains cannot have CNAME records.
Question and response
Question
dig online-presentations.com. NS
Answer
online-presentations.com. 5 NS ns2.online-presentations.com.
online-presentations.com. 5 NS ns1.online-presentations.com.
Authority
The response has no authority records.
Additional
ns1.online-presentations.com. 5 A 51.161.71.117
ns2.online-presentations.com. 5 A 192.95.30.213
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0