That's a leftover from back when IPv6 was very new (yes these utilities are that old), and the networking utilities (ping, traceroute, etc) understood only IPv4. It's no longer necessary, all relevant networking utilities have since been upgraded to work with both IPv4 and IPv6; you can use just "ping" with a IPv6 address and it should work.
> You can use just "ping" with a IPv6 address and it should work
Not on BSD-derived operating systems (macOS included). You must use ping6 to ping an IPv6 address (including a hostname that only publishes AAAA records.)
From `man ping6` on macOS Sonoma:
> There have been many discussions on why we separate ping6 and ping(8). Some people argued that it would be more convenient to uniform the ping command for both IPv4 and IPv6.
> The following are an answer to the request:
> From a developer's point of view: since the underling raw sockets API is totally different between IPv4 and IPv6, we would end up having two types of code base. There would actually be less benefit to uniform the two commands into a single command from the developer's standpoint.
> From an operator's point of view: unlike ordinary network applications like remote login tools, we are usually aware of address family when using network management tools. We do not just want to know the reachability to the host, but want to know the reachability to the host via a particular network protocol such as IPv6. Thus, even if we had a unified ping(8) command for both IPv4 and IPv6, we would usually type a -6 or -4 option (or something like those) to specify the particular address family. This essentially means that we have two different commands.
Interesting. I’ve tried macOS and OpenBSD and they both require using ping6 to ping IPv6 addresses. I wonder if FreeBSD changed this recently or if it was always that way. Regardless, macOS is the elephant in the room here as it’s a lot more popular than any of the (other) BSD’s.
I often use ping to check if a machine is alive or is reachable at large. Then it might be more informative if ping tried all addresses the name resolves to. You wouldn't need to specify the protocol version.
