Mildly cursed factoid about UNC paths:
- UNC Paths can contain IP addresses such as \\192.168.1.1\share
- IPv6 addresses are supported as well
- IPv6 addresses contain colons
- can't have colons in Windows paths since colons are reserved for drive letters
So Microsoft came up with the the ipv6-literal.net domain that's special-cased by Windows so you can to write IPv6 addresses in UNC paths as 2a0e-3c0--21.ipv6-literal.net without it hitting any resolvers.
Turns out, it's worse than this: The ipv6-literal.net shenanigans aren't limited to UNC paths.
It works in all places:
> ping 2a0e-3c0--21.ipv6-literal.net
Pinging 2a0e:3c0::21 with 32 bytes of data:
Also works in browsers: http://2a0e-3c0--21.ipv6-literal.net/
Thanks to @casandro for asking.
@karotte @casandro Not on Linux it seems:
```
stuartl@vk4msl-tp:~$ ping 2a0e-3c0--21.ipv6-literal.net
ping: 2a0e-3c0--21.ipv6-literal.net: Name or service not known
stuartl@vk4msl-tp:~$ uname -a
Linux vk4msl-tp 6.12.12+bpo-rt-amd64 #1 SMP PREEMPT_RT Debian 6.12.12-1~bpo12+1 (2025-02-23) x86_64 GNU/Linux
```
As I recall…
Windows 2000 had IPv6 as a "technology preview" that had to be separately downloaded and installed.
Windows XP whad it disabled by default, but did otherwise ship with it.
Windows Vista and later turned it on by default.
Anything currently supported by Microsoft right now will have it turned on unless the user/administrator turns it off manually.
So "only few" actually covers a lot of users.
Lukas
Stuart Longland (VK4MSL)
Christian Berger DECT 2763