[abotsis]

Wow, this. One thing I didn’t see mentioned was “0”. You mentioned it, but it didn’t grok to something I know to work in some implementations: “ping 0” behaves like “ping 127.0.0.1”.

[nealabq]

Maybe ping is treating 0 like 0.0.0.0 aka INADDR_ANY ( https://en.wikipedia.org/wiki/0.0.0.0 ). And interpreting it as all the IPv4 addrs mapped to the local machine (including localhost).