Apex domains cannot have CNAME records.
Question and response
Question
dig bestgo.pl. NS
Answer
bestgo.pl. 5 NS ns1.bestgo.pl.
bestgo.pl. 5 NS ns3.bestgo.pl.
Authority
The response has no authority records.
Additional
ns1.bestgo.pl. 5 A 213.5.40.41
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0