mail19.rt.RU has no NS records.
NS records for this zone are defined at rt.RU.
NS records for this zone are defined at rt.RU.
Question and response
Question
dig mail19.rt.RU. NS
Answer
The response has no answer records.
Authority
rt.ru. 600 SOA ns1.rostelecom.ru. hostmaster.rt.ru. 2026022601 600 7200 1209600 600
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0