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