mxbackup.icewarp.net has no NS records.
NS records for this zone are defined at icewarp.net.
NS records for this zone are defined at icewarp.net.
Question and response
Question
dig mxbackup.icewarp.net. NS
Answer
The response has no answer records.
Authority
icewarp.net. 1800 SOA delilah.ns.cloudflare.com. dns.cloudflare.com. 2395844364 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0