mail.concresa.com has no NS records.
NS records for this zone are defined at concresa.com.
NS records for this zone are defined at concresa.com.
Question and response
Question
dig mail.concresa.com. NS
Answer
The response has no answer records.
Authority
concresa.com. 10800 SOA ns1.net.mexline.com. devillasanter.concresa.com. 1768023672 10800 3600 604800 10800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0