mail.ib.systems has no CNAME records.
Question and response
Question
dig mail.ib.systems. NS
Answer
The response has no answer records.
Authority
ib.systems. 926 SOA dara.ns.cloudflare.com. dns.cloudflare.com. 2397451899 10000 2400 604800 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0