mx01.sg.secom-cloud.jp has no CNAME records.
Question and response
Question
dig mx01.sg.secom-cloud.jp. NS
Answer
The response has no answer records.
Authority
secom-cloud.jp. 236 SOA ns01.secomtrust.net. sdc-sec.secomtrust.net. 2024121000 7200 1800 2419200 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0