mx4.mangotele.com has no NS records.
NS records for this zone are defined at mangotele.com.
NS records for this zone are defined at mangotele.com.
Question and response
Question
dig mx4.mangotele.com. NS
Answer
The response has no answer records.
Authority
mangotele.com. 300 SOA nss1.mango-office.ru. techsupport.mangotele.com. 2026012704 300 300 604800 300
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0