Apex domains cannot have CNAME records.
Question and response
Question
dig fakturownia.pl. NS
Answer
fakturownia.pl. 5 NS ns-934.awsdns-52.net.
fakturownia.pl. 5 NS ns-117.awsdns-14.com.
fakturownia.pl. 5 NS ns-1810.awsdns-34.co.uk.
fakturownia.pl. 5 NS ns-1221.awsdns-24.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0