mail.erlan.com.ar has no NS records.
NS records for this zone are defined at erlan.com.ar.
NS records for this zone are defined at erlan.com.ar.
Question and response
Question
dig mail.erlan.com.ar. NS
Answer
The response has no answer records.
Authority
erlan.com.ar. 180 SOA ns10.digicertdns.com. dns.digicertdns.com. 2009010144 43200 3600 1209600 180
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0