mx.vnet.sk has no NS records.
NS records for this zone are defined at vnet.sk.
NS records for this zone are defined at vnet.sk.
Question and response
Question
dig mx.vnet.sk. NS
Answer
The response has no answer records.
Authority
vnet.sk. 3600 SOA ns.vnet.sk. hostmaster.vnet.sk. 2026022303 3600 900 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0