DENMTA01.authorize.net has no CNAME records.
Question and response
Question
dig DENMTA01.authorize.net. NS
Answer
The response has no answer records.
Authority
authorize.net. 1800 SOA lloyd.ns.cloudflare.com. dns.cloudflare.com. 2388838934 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0