mail.xenox.systems has no NS records.
NS records for this zone are defined at xenox.systems.
NS records for this zone are defined at xenox.systems.
Question and response
Question
dig mail.xenox.systems. NS
Answer
The response has no answer records.
Authority
xenox.systems. 86400 SOA ns1.xenox-systems.net. postmaster.xenox.systems. 2025050912 86400 10800 3600000 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0