Apex domains cannot have CNAME records.
Question and response
Question
dig static.tld.pl. NS
Answer
static.tld.pl. 5 NS ns2.tld.pl.
static.tld.pl. 5 NS ns1.tld.pl.
Authority
The response has no authority records.
Additional
ns1.tld.pl. 5 A 94.152.254.101
ns2.tld.pl. 5 A 94.152.255.101
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0