Apex domains cannot have CNAME records.
Question and response
Question
dig zwhhosting.com. NS
Answer
zwhhosting.com. 4 NS ns-a1.cloud.z.com.
zwhhosting.com. 4 NS ns-a3.cloud.z.com.
zwhhosting.com. 4 NS ns-a4.cloud.z.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0