ns.dns4.cz has no NS records.
NS records for this zone are defined at dns4.cz.
NS records for this zone are defined at dns4.cz.
Question and response
Question
dig ns.dns4.cz. NS
Answer
The response has no answer records.
Authority
dns4.cz. 86400 SOA ns.dns4.cz. hostmaster.active24.cz. 2012121401 10800 1800 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0