Apex domains cannot have CNAME records.
Question and response
Question
dig zomro.su. NS
Answer
zomro.su. 5 NS bella.ns.cloudflare.com.
zomro.su. 5 NS carter.ns.cloudflare.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0