You’ve probably heard of RFC1918 – the well-known set of networks assigned for use in off-Internet, private networks. In fact there’s a much more useful RFC, one which lists not only these but a group of other networks and subnets assigned by IANA for so-called “special purposes”. Networks have been reserved for many uses including documentation, benchmarking tests, and of course the loopback network 127.0.0.0/8 to name but a few.
RFC5735 has recently been released to update this list, and it’s a short read that’s well worth running through some time with a cup of tea. One new highlight in this updated version is that there are now three subnets assigned for documentation purposes. This means if you’re documenting an example network topology with routing, you can use the three example subnets given:
192.0.2.0/24 198.51.100.0/24 203.0.113.0/24
In the same vein, there’s also RFC2606 which details reserved domain names that can be used for either documentation or private systems. Both RFCs help to extend the lifetime of documentation by making it more generic, useful and readable.
P.S. You can track new RFC releases at this RSS feed: http://tools.ietf.org/html/new-rfcs.rss