These DNS names and IP ranges are reserved (on the Internet) for use in specific situations, including examples, documentation and non-unique local assignment. As such, they are not available for unique assignment on the Internet and, with the exception of those reserved specifically for that purpose, should not be assigned on local networks that require proper Internet connectivity.

Because these DNS names and IP ranges are reserved, they can be used freely in anonymizing network assignments without risk of accidentally referring to some other real-world entity’s actual globally unique assignment either at the present time or in the future.

DNS names

RFC 2606 reserves four top-level domain names for use for examples and documentation:

  • test
  • example
  • invalid
  • localhost

RFC 2606 also reserves three second-level domain names for use for examples and documentation:

  • example.com
  • example.net
  • example.org

RFC 8375 reserves a single, local-scope, second-level domain name for use for local name service in residential homenets:

  • home.arpa

Any names under any of these domains are, by consequence, available for use for the same purpose. For example, since “home.arpa” is reserved for local name service in residential homenets, to use “laptop.home.arpa” within such local name service is appropriate; similarly, since “example” as a top-level domain is reserved for examples, to use a name such as “oceania-web47-abc.example” as an example is appropriate.

Since these domain names are reserved for their purpose, no coordination with anyone else who might also be using them is required for such use. It is however worth noting that some such names might also resolve meaningfully on the global Internet; for example, “www.example.com” resolves to the IP address of a host that provides HTTP service and serves a web page briefly describing the purpose of the domain.

IPv4 networks

RFC 5737 reserves three IPv4 network address blocks out of the IPv4 globally routable unicast space for use for examples and documentation:

  • 192.0.2.0/24 (192.0.2.0 – 192.0.2.255) (originally by the now obsolete RFC 1166)
  • 198.51.100.0/24 (198.51.100.0 – 198.51.100.255)
  • 203.0.113.0/24 (203.0.113.0 – 203.0.113.255)

RFC 1918 reserves three IPv4 network address blocks for private assignments, typically but not exclusively local area networks:

  • 10.0.0.0/8 (10.0.0.0 – 10.255.255.255)
  • 172.16.0.0/12 (172.16.0.0 – 172.31.255.255)
  • 192.168.0.0/16 (192.168.0.0 – 192.168.255.255)

For a local network that requires Internet connectivity, it is generally preferable to use some portion of the RFC 1918 address space behind a network address translation (NAT) device. However, when circumstances so require, specifically obtained globally routable addresses can also be used. Never pick an IP address at random for local use.

IPv6 networks

RFC 3849 reserves a single IPv6 network address block out of the IPv6 globally routable unicast space for use for examples and documentation:

  • 2001:DB8::/32

For a local network that requires Internet connectivity, use either globally routable addresses or a netblock assigned as described in RFC 4193 sections 3.1 and 3.2.2 using FC00::/7 space. Never pick an IP address at random for local use.

EUI-48 and EUI-64 MAC addresses

Note that MAC addresses are normally not routed outside of the local subnet, but they can be used to generate particularly IPv6 addresses and as such may be exposed directly or indirectly on a larger network. For example, RFC 2464 defines stateless IPv6 address autoconfiguration for link-local addresses based on the EUI-64 address of a network interface, and RFC 4193 uses an EUI-64 identifier in the process of generating a unique local IPv6 unicast address prefix. Particularly in cases where the EUI-48 or EUI-64 identifier is used directly, such as in RFC 2464, addresses generated based on the ranges reserved for use in documentation should also be safe to use in documentation and examples. As discussed in for example RFC 4941 and RFC 7217, for several reasons, use of the EUI-48 or EUI-64 identifier directly should be avoided on actual networks.

RFC 7042 reserves two EUI-48 ranges for use in documentation:

  • 00-00-5E-00-53-00 through 00-00-5E-00-53-FF for unicast
  • 01-00-5E-90-10-00 through 01-00-5E-90-10-FF for multicast

RFC 7042 also reserves several unicast EUI-64 ranges for use in documentation:

  • 00-00-5E-EF-10-00-00-00 through 00-00-5E-EF-10-00-00-FF
  • 00-00-5E-FE-C0-00-02-00 through 00-00-5E-FE-C0-00-02-FF
  • 00-00-5E-FE-C6-33-64-00 through 00-00-5E-FE-C6-33-64-FF
  • 00-00-5E-FE-CB-00-71-00 through 00-00-5E-FE-CB-00-71-FF
  • 00-00-5E-FF-FE-00-53-00 through 00-00-5E-FF-FE-00-53-FF
  • 00-00-5E-FE-EA-C0-00-02 (specific EUI-64 address)
  • 00-00-5E-FE-EA-C6-33-64 (specific EUI-64 address)
  • 00-00-5E-FE-EA-CB-00-71 (specific EUI-64 address)

RFC 7042 also reserves several multicast EUI-64 ranges for use in documentation:

  • 01-00-5E-EF-10-00-00-00 through 01-00-5E-EF-10-00-00-FF
  • 01-00-5E-FE-C0-00-02-00 through 01-00-5E-FE-C0-00-02-FF
  • 01-00-5E-FE-C6-33-64-00 through 01-00-5E-FE-C6-33-64-FF
  • 01-00-5E-FE-CB-00-71-00 through 01-00-5E-FE-CB-00-71-FF
  • 01-00-5E-FE-EA-C0-00-02 (specific EUI-64 address)
  • 01-00-5E-FE-EA-C6-33-64 (specific EUI-64 address)
  • 01-00-5E-FE-EA-CB-00-71 (specific EUI-64 address)