Apex domains cannot have CNAME records.
Question and response
Question
dig staticip.ostnet.pl. NS
Answer
staticip.ostnet.pl. 5 NS dns1.ostnet.pl.
staticip.ostnet.pl. 5 NS dns2.ostnet.pl.
Authority
The response has no authority records.
Additional
dns1.ostnet.pl. 5 A 62.133.128.10
dns2.ostnet.pl. 5 A 62.133.128.20
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0