Apex domains cannot have CNAME records.
Question and response
Question
dig asta-net.com.pl. NS
Answer
asta-net.com.pl. 5 NS ns1.asta-net.pl.
asta-net.com.pl. 5 NS ns2.asta-net.pl.
Authority
The response has no authority records.
Additional
ns1.asta-net.pl. 5 A 86.63.64.62
ns2.asta-net.pl. 5 A 86.63.64.61
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0