echo.mxrouting.net has no CNAME records.
Question and response
Question
dig echo.mxrouting.net. NS
Answer
The response has no answer records.
Authority
mxrouting.net. 2082 SOA ns21.cloudns.net. support.cloudns.net. 2026012302 7200 1800 1209600 3600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0