us.dnsdocloud.com has no CNAME records.
Question and response
Question
dig us.dnsdocloud.com. NS
Answer
The response has no answer records.
Authority
dnsdocloud.com. 1144 SOA ns1.virtualns.net. dns.virtualname.net. 1771459200 14400 3600 1209600 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0