mx.cittel.ru has no NS records.
NS records for this zone are defined at cittel.ru.
NS records for this zone are defined at cittel.ru.
Question and response
Question
dig mx.cittel.ru. NS
Answer
The response has no answer records.
Authority
cittel.ru. 86400 SOA ns.cittel.ru. hostmaster.cittel.ru. 2026011900 3600 900 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0