fb2.aams.jp has no CNAME records.
Question and response
Question
dig fb2.aams.jp. NS
Answer
The response has no answer records.
Authority
aams.jp. 300 SOA www1.aams.jp. aams-nic.bbsec.co.jp. 2023122001 300 60 604800 300
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0