cms7.avcr.cz has no NS records.
NS records for this zone are defined at avcr.cz.
NS records for this zone are defined at avcr.cz.
Question and response
Question
dig cms7.avcr.cz. NS
Answer
The response has no answer records.
Authority
avcr.cz. 600 SOA academy.cas.cz. domeny.ssc.cas.cz. 1678089621 7200 1800 604800 86400
Additional
. 0 OPT ; payload 1472, xrcode 0, version 0, flags 0