Apex domains cannot have CNAME records.
Question and response
Question
dig lodz.pl. NS
Answer
lodz.pl. 5 NS ns1.tpnet.pl.
lodz.pl. 5 NS ns1.task.gda.pl.
lodz.pl. 5 NS dns.man.lodz.pl.
lodz.pl. 5 NS dns2.man.lodz.pl.
Authority
The response has no authority records.
Additional
dns.man.lodz.pl. 5 A 212.51.192.2
ns1.task.gda.pl. 5 A 153.19.250.101
dns2.man.lodz.pl. 5 A 212.51.192.5
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0