mail.em4service.cz has no NS records.
NS records for this zone are defined at em4service.cz.
NS records for this zone are defined at em4service.cz.
Question and response
Question
dig mail.em4service.cz. NS
Answer
The response has no answer records.
Authority
em4service.cz. 1800 SOA ns1.zcom.cz. hostmaster.zcom.cz. 1773622075 10800 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0