mx.insulardepuertas.com has no NS records.
NS records for this zone are defined at insulardepuertas.com.
NS records for this zone are defined at insulardepuertas.com.
Question and response
Question
dig mx.insulardepuertas.com. NS
Answer
The response has no answer records.
Authority
insulardepuertas.com. 3600 SOA dns.insulardepuertas.com. hostmaster.insulardepuertas.com. 1339677040 43200 3600 604800 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0