mail.vladivostok.RU has no NS records.
NS records for this zone are defined at vladivostok.RU.
NS records for this zone are defined at vladivostok.RU.
Question and response
Question
dig mail.vladivostok.RU. NS
Answer
The response has no answer records.
Authority
vladivostok.ru. 3600 SOA ns.vlc.ru. admin.vlc.ru. 19 360 300 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0