smtp.dosdrive.com has no CNAME records.
Question and response
Question
dig smtp.dosdrive.com. NS
Answer
The response has no answer records.
Authority
dosdrive.com. 10800 SOA ns1.dosdrive.com. hostmaster.dosdrive.com. 2020050700 14400 3600 1209600 86400
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0