aus1.vtigermail.com has no NS records.
NS records for this zone are defined at vtigermail.com.
NS records for this zone are defined at vtigermail.com.
Question and response
Question
dig aus1.vtigermail.com. NS
Answer
The response has no answer records.
Authority
vtigermail.com. 600 SOA pdns01.domaincontrol.com. dns.jomax.net. 2026031100 28800 7200 604800 600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0