mdns2.appriver.com has no CNAME records.
Question and response
Question
dig mdns2.appriver.com. NS
Answer
The response has no answer records.
Authority
appriver.com. 296 SOA hugh.ns.cloudflare.com. dns.cloudflare.com. 2397032929 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0