The use of the colon as an address separator in IPv6 has caused some mild annoyances over the years. Microsoft created unique solution, essentially mapping colons to dashes and putting this in a top-level domain. They chose ipv6-literal.net and implemented this internal to their software.
In the IPv4 world, the utility of having addresses resolvable as hostnames in DNS had sufficient demand that someone set up xip.io. Unfortunately I've never seen such an equivalent for IPv6 addresses, leaving folk to use the bracket notation and hope for the best.
