zix.com.2.0001.arsmtp.com has no NS records.
NS records for this zone are defined at 0001.arsmtp.com.
NS records for this zone are defined at 0001.arsmtp.com.
Question and response
Question
dig zix.com.2.0001.arsmtp.com. NS
Answer
The response has no answer records.
Authority
0001.arsmtp.com. 600 SOA mdns1.appriver.com. support.appriver.com. 11137916 900 600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0