Apex domains cannot have CNAME records.
Question and response
Question
dig pomocplay.pl. NS
Answer
pomocplay.pl. 5 NS ns2.project4.pl.
pomocplay.pl. 5 NS ns1.project4.pl.
pomocplay.pl. 5 NS ns3.project4.pl.
Authority
The response has no authority records.
Additional
ns1.project4.pl. 5 A 89.108.195.18
ns2.project4.pl. 5 A 89.108.195.19
ns3.project4.pl. 5 A 89.108.202.18
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0