mail.landvps.ru has no NS records.
NS records for this zone are defined at landvps.ru.
NS records for this zone are defined at landvps.ru.
Question and response
Question
dig mail.landvps.ru. NS
Answer
The response has no answer records.
Authority
landvps.ru. 1800 SOA adelaide.ns.cloudflare.com. dns.cloudflare.com. 2398705902 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0