mail3.zcom.cz has no NS records.
NS records for this zone are defined at zcom.cz.
NS records for this zone are defined at zcom.cz.
Question and response
Question
dig mail3.zcom.cz. NS
Answer
The response has no answer records.
Authority
zcom.cz. 1800 SOA ns1.zcom.cz. hostmaster.zcom.cz. 1772945134 10800 3600 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0