edns.registrar-servers.com has no NS records.
NS records for this zone are defined at registrar-servers.com.
NS records for this zone are defined at registrar-servers.com.
Question and response
Question
dig edns4.ultradns.com. NS
Answer
The response has no answer records.
Authority
ultradns.com. 60 SOA pdns196.ultradns.net. domains.vercara.com. 2017038255 10800 3600 86400 60
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0