mail06.sharestage.com has no CNAME records.
Question and response
Question
dig mail06.sharestage.com. NS
Answer
The response has no answer records.
Authority
sharestage.com. 120 SOA ns05.sharestage.com. postmaster.sharestage.com. 2025110715 10800 3600 604800 600
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0