PDNS90.ULTRADNS.NET has no CNAME records.
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 1232, xrcode 0, version 0, flags 0