mailgw.tu.kielce.pl has no NS records.
NS records for this zone are defined at tu.kielce.pl.
NS records for this zone are defined at tu.kielce.pl.
Question and response
Question
dig mailgw.tu.kielce.pl. NS
Answer
The response has no answer records.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0