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:
- RFC 2606 - Reserved Top Level DNS Names
- RFC 5737 - IPv4 Address Blocks Reserved for Documentation
- RFC 3849 - IPv6 Address Prefix Reserved for Documentation
- RFC 9637 - Expanding the IPv6 Documentation Space
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.