mx.mail-servicios.com has no NS records.
NS records for this zone are defined at mail-servicios.com.
NS records for this zone are defined at mail-servicios.com.
Question and response
Question
dig mx.mail-servicios.com. NS
Answer
The response has no answer records.
Authority
mail-servicios.com. 180 SOA ns10.dnsmadeeasy.com. dns.dnsmadeeasy.com. 2009010297 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0