PDNS90.ULTRADNS.NET has no NS records.
NS records for this zone are defined at ULTRADNS.NET.
NS records for this zone are defined at ULTRADNS.NET.
Question and response
Question
dig PDNS90.ULTRADNS.NET. NS
Answer
The response has no answer records.
Authority
ultradns.net. 60 SOA udns1.ultradns.net. domains.vercara.com. 2019110412 900 600 604800 60
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0