mx.emaillabs.net.pl has no NS records.
NS records for this zone are defined at emaillabs.net.pl.
NS records for this zone are defined at emaillabs.net.pl.
Question and response
Question
dig mx.emaillabs.net.pl. NS
Answer
The response has no answer records.
Authority
emaillabs.net.pl. 1800 SOA athena.ns.cloudflare.com. dns.cloudflare.com. 2397511627 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0