mx.SPD-MGTS.RU has no NS records.
NS records for this zone are defined at SPD-MGTS.RU.
NS records for this zone are defined at SPD-MGTS.RU.
Question and response
Question
dig mx.SPD-MGTS.RU. NS
Answer
The response has no answer records.
Authority
spd-mgts.ru. 3600 SOA ns1.spd-mgts.ru. noc.spd-mgts.ru. 2020061601 10800 1800 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0