mx.fibercorp.com.ar has no NS records.
NS records for this zone are defined at fibercorp.com.ar.
NS records for this zone are defined at fibercorp.com.ar.
Question and response
Question
dig mx.fibercorp.com.ar. NS
Answer
The response has no answer records.
Authority
fibercorp.com.ar. 21600 SOA o200.prima.com.ar. dnsmaster.prima.com.ar. 2025111805 86400 21640 604800 259200
Additional
. 0 OPT ; payload 512, xrcode 0, version 0, flags 0