fe.rimail.app has no NS records.
NS records for this zone are defined at rimail.app.
NS records for this zone are defined at rimail.app.
Question and response
Question
dig fe.rimail.app. NS
Answer
The response has no answer records.
Authority
rimail.app. 3601 SOA dns1.registrar-servers.com. hostmaster.registrar-servers.com. 1768955520 43200 3600 604800 3601
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0