cz4.xetmail.com has no NS records.
NS records for this zone are defined at xetmail.com.
NS records for this zone are defined at xetmail.com.
Question and response
Question
dig cz4.xetmail.com. NS
Answer
The response has no answer records.
Authority
xetmail.com. 3600 SOA ns1.atw.hu. admin\@xetdns.com. 2774009442 43200 7200 1209600 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0