mta.xtra.co.nz has no NS records.
NS records for this zone are defined at xtra.co.nz.
NS records for this zone are defined at xtra.co.nz.
Question and response
Question
dig mta.xtra.co.nz. NS
Answer
The response has no answer records.
Authority
xtra.co.nz. 900 SOA ns-1109.awsdns-10.org. awsdns-hostmaster.amazon.com. 1 7200 900 1209600 86400
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0