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