itmx-smtp-srv.rtmxdomain.com.mx has no NS records.
NS records for this zone are defined at com.mx.
NS records for this zone are defined at com.mx.
Question and response
Question
dig itmx-smtp-srv.rtmxdomain.com.mx. NS
Answer
The response has no answer records.
Authority
com.mx. 1800 SOA m.mx-ns.mx. hostmaster.nic.mx. 1773595331 900 900 604800 1800
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0