Apex domains cannot have CNAME records.
Question and response
Question
dig biaman.pl. NS
Answer
biaman.pl. 4 NS dns.man.bialystok.pl.
biaman.pl. 4 NS master.man.bialystok.pl.
Authority
The response has no authority records.
Additional
master.man.bialystok.pl. 4 A 212.33.64.18
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0