mx4.prexmail.ru has no NS records.
NS records for this zone are defined at prexmail.ru.
NS records for this zone are defined at prexmail.ru.
Question and response
Question
dig mx4.prexmail.ru. NS
Answer
The response has no answer records.
Authority
prexmail.ru. 53 SOA a.ns.selectel.ru. support.selectel.ru. 2026031202 10800 3600 604800 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0