mx.esigno.com has no NS records.
NS records for this zone are defined at esigno.com.
NS records for this zone are defined at esigno.com.
Question and response
Question
dig mx.esigno.com. NS
Answer
The response has no answer records.
Authority
esigno.com. 3600 SOA diana.designplus.cz. domeny.designplus.cz. 2021042248 3600 600 86400 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0