mail-ext.interoute.net has no NS records.
NS records for this zone are defined at interoute.net.
NS records for this zone are defined at interoute.net.
Question and response
Question
dig mail-ext.interoute.net. NS
Answer
The response has no answer records.
Authority
interoute.net. 600 SOA ns63.domaincontrol.com. dns.jomax.net. 2025081800 28800 7200 604800 600
Additional
. 0 OPT ; payload 1280, xrcode 0, version 0, flags 0