例示用のIPアドレスに123.123.123.1とか使うと危険が危ないよ中国が持ってるよ
https://datatracker.ietf.org/doc/html/rfc5737
IETF DatatrackerRFC 5737: IPv4 Address Blocks Reserved for DocumentationThree IPv4 unicast address blocks are reserved for use in examples in specifications and other documents. This document describes the use of these blocks. This document is not an Internet Standards Track specification; it is published for informational purposes.
まだなんとなく期待通り動いてそうw
$ sh value-domain.sh github.com
not blocked
$ sh value-domain.sh mstdn.jp
blocked