dnsdot.ddns.net has no NS records.
NS records for this zone are defined at ddns.net.
NS records for this zone are defined at ddns.net.
Question and response
Question
dig dnsdot.ddns.net. NS
Answer
The response has no answer records.
Authority
ddns.net. 1800 SOA nf1.no-ip.com. hostmaster.no-ip.com. 2678978867 10800 1800 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0