sender.transtk.ru has no NS records.
NS records for this zone are defined at transtk.ru.
NS records for this zone are defined at transtk.ru.
Question and response
Question
dig sender.transtk.ru. NS
Answer
The response has no answer records.
Authority
transtk.ru. 3600 SOA dns-prim.transtk.ru. nsmaster.transtk.ru. 2024061301 900 600 86400 3600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0