mail.ihsmarkit.com has no CNAME records.
Question and response
Question
dig mail.ihsmarkit.com. NS
Answer
The response has no answer records.
Authority
ihsmarkit.com. 102 SOA ns1.ihsmarkit.com. hostmaster.ihsmarkit.com. 2022033198 900 3600 2419200 900
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0