Apex domains cannot have CNAME records.
Question and response
Question
dig omega.com.pl. NS
Answer
omega.com.pl. 5 NS 95.51.156.178.
omega.com.pl. 5 NS ns2.omega.com.pl.
omega.com.pl. 5 NS ns1.omega.com.pl.
Authority
The response has no authority records.
Additional
ns1.omega.com.pl. 5 A 95.51.156.178
ns2.omega.com.pl. 5 A 95.51.156.178
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0