smtp.iwltransport.com has no NS records.
NS records for this zone are defined at iwltransport.com.
NS records for this zone are defined at iwltransport.com.
Question and response
Question
dig smtp.iwltransport.com. NS
Answer
The response has no answer records.
Authority
iwltransport.com. 900 SOA ns1-auth.etb.net.co. postmaster.etb.net.co. 2015052857 10800 3600 2419200 900
Additional
. 0 OPT ; payload 1220, xrcode 0, version 0, flags 0