smtp-37737.nodevm.com has no CNAME records.
Question and response
Question
dig smtp-37737.nodevm.com. NS
Answer
The response has no answer records.
Authority
nodevm.com. 12 SOA ns1.kcdc.namehero.com. kcdc.namehero.com. 0 1800 3600 60 60
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0