Apex domains cannot have CNAME records.
Question and response
Question
dig speednet.bg. NS
Answer
speednet.bg. 5 NS sns.speednet.bg.
speednet.bg. 5 NS pns.speednet.bg.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0