mx1.netia.com.pl has no NS records.
NS records for this zone are defined at netia.com.pl.
NS records for this zone are defined at netia.com.pl.
Question and response
Question
dig mx1.netia.com.pl. NS
Answer
The response has no answer records.
Authority
netia.com.pl. 86400 SOA ns1.internetia.pl. root.ns1.internetia.pl. 2025030400 86400 7200 2592000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0