smtp146255.reasonable53.com has no CNAME records.
Question and response
Question
dig smtp146255.reasonable53.com. NS
Answer
The response has no answer records.
Authority
reasonable53.com. 10800 SOA ns1.onlydomains.com. root.onlydomains.com. 2020032701 28800 7200 604800 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0