mx1b20.thinline.cz has no NS records.
NS records for this zone are defined at thinline.cz.
NS records for this zone are defined at thinline.cz.
Question and response
Question
dig mx1b20.thinline.cz. NS
Answer
The response has no answer records.
Authority
thinline.cz. 1800 SOA ns1.thinline.cz. hostmaster.thinline.cz. 1533063932 86400 300 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0