Apex domains cannot have CNAME records.
Question and response
Question
dig host2vps.com. NS
Answer
host2vps.com. 5 NS ns5.ikoula.com.
host2vps.com. 5 NS ns4.ikoula.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0