mx1.leon.pl has no NS records.
NS records for this zone are defined at leon.pl.
NS records for this zone are defined at leon.pl.
Question and response
Question
dig mx1.leon.pl. NS
Answer
The response has no answer records.
Authority
leon.pl. 43200 SOA ns1.leon.pl. admin.leon.pl. 2026020902 3600 1200 2419200 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0