2001:db8? Ah jeez, that's gotta be phony.

You know how on TV and in movies, if someone calls a phone number, it starts with 555 because that's a reserved prefix for fictional use? Well, those exist for domain names and IP addresses too:

If you're putting a fully qualified domain name or an IP address in your documentation, use a proper fake one!

I just had to go and update a bunch of IP addresses in tycoon's documentation and unit tests. I should've referred to these standards from the start. It would have saved me the work of coming up with fake addresses in the first place.