mail.ratm.ru has no NS records.
NS records for this zone are defined at ratm.ru.
NS records for this zone are defined at ratm.ru.
Question and response
Question
dig mail.ratm.ru. NS
Answer
The response has no answer records.
Authority
ratm.ru. 900 SOA ns.ratm.ru. root.ratm.ru. 2025120909 86400 900 2419200 432000
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0