mx2.mcntt.ru has no NS records.
NS records for this zone are defined at mcntt.ru.
NS records for this zone are defined at mcntt.ru.
Question and response
Question
dig mx2.mcntt.ru. NS
Answer
The response has no answer records.
Authority
mcntt.ru. 3600 SOA ns.ntt.ru. noc.mcntt.ru. 20070818 86400 7200 3600000 172800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0