mail.oxit.cz has no NS records.
NS records for this zone are defined at oxit.cz.
NS records for this zone are defined at oxit.cz.
Question and response
Question
dig mail.oxit.cz. NS
Answer
The response has no answer records.
Authority
oxit.cz. 38400 SOA shinzon.blueboard.cz. hostmaster.blueboard.cz. 2017072611 10800 3600 604800 38400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0