smtp.hostpro.ru has no NS records.
NS records for this zone are defined at hostpro.ru.
NS records for this zone are defined at hostpro.ru.
Question and response
Question
dig smtp.hostpro.ru. NS
Answer
The response has no answer records.
Authority
hostpro.ru. 1800 SOA major.ns.cloudflare.com. dns.cloudflare.com. 2397602444 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0