mx.drhinternet.net has no CNAME records.
Question and response
Question
dig mx.drhinternet.net. NS
Answer
The response has no answer records.
Authority
drhinternet.net. 248 SOA ns1.drh.net. root.ns1.drh.net. 2026022301 86400 180 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0