mx1.k2.pl has no NS records.
NS records for this zone are defined at k2.pl.
NS records for this zone are defined at k2.pl.
Question and response
Question
dig mx1.k2.pl. NS
Answer
The response has no answer records.
Authority
k2.pl. 60 SOA dns12.ovh.net. tech.ovh.net. 2026012600 86400 3600 3600000 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0