Apex domains cannot have CNAME records.
Question and response
Question
dig sfire.pl. NS
Answer
sfire.pl. 1 NS ns1.seohost.pl.
sfire.pl. 1 NS ns2.seohost.pl.
Authority
The response has no authority records.
Additional
ns1.seohost.pl. 1 A 185.200.47.250
ns1.seohost.pl. 1 A 188.210.221.52
ns2.seohost.pl. 1 A 188.210.221.179
ns2.seohost.pl. 1 A 188.210.223.253
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0