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