correosmtp.aena.es has no NS records.
NS records for this zone are defined at aena.es.
NS records for this zone are defined at aena.es.
Question and response
Question
dig correosmtp.aena.es. NS
Answer
The response has no answer records.
Authority
aena.es. 900 SOA dns6.aena.es. please_set_email.absolutely.nowhere. 871 10800 3600 2592000 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0