mail.key-p.com has no CNAME records.
Question and response
Question
dig mail.key-p.com. NS
Answer
The response has no answer records.
Authority
key-p.com. 1548 SOA ns01.key-p.co.jp. root.ns01.key-p.co.jp. 2025041801 3600 14400 3600000 1800
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0