Apex domains cannot have CNAME records.
Question and response
Question
dig interwan.pl. NS
Answer
interwan.pl. 5 NS dns3.nano.pl.
interwan.pl. 5 NS dns2.nano.pl.
interwan.pl. 5 NS dns1.nano.pl.
Authority
The response has no authority records.
Additional
dns1.nano.pl. 5 A 94.152.255.103
dns2.nano.pl. 5 A 94.152.254.103
dns3.nano.pl. 5 A 94.152.254.153
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0