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Documentation IP Addresses

You landed here because the address you looked up is reserved for use in documentation and examples. RFC 5737 reserves three IPv4 ranges and RFC 3849 reserves one IPv6 prefix, all of them guaranteed to never be delegated to any real network.

TEST-NET-1
192.0.2.0/24
TEST-NET-2
198.51.100.0/24
TEST-NET-3
203.0.113.0/24
IPv6 documentation
2001:db8::/32

Frequently asked questions

Is 192.0.2.1 a real IP address?

No — it is a documentation address. RFC 5737 reserves 192.0.2.0/24, 198.51.100.0/24, and 203.0.113.0/24 (nicknamed TEST-NET-1, TEST-NET-2, and TEST-NET-3) for use in examples, textbooks, RFCs, and vendor training material. They are not delegated to any operator and should never appear on the public internet.

Why does my packet capture show 198.51.100.x?

Someone copy-pasted an example configuration without changing the addresses. It is extremely common for vendor training labs, tutorial blog posts, and Cisco/Juniper/Arista certification guides to use TEST-NET-2 verbatim. If a production network is actually sending those packets, you are looking at a misconfigured device that was brought up with lab defaults still in place.

What RFC reserves these addresses?

RFC 5737 (published January 2010) defines the three IPv4 documentation ranges. RFC 3849 (published July 2004) reserves 2001:db8::/32 as the IPv6 documentation prefix. Both exist to prevent the 'example in a book accidentally points at a real network' problem that was common before they were published.

Can I use 2001:db8::/32 on my real network?

You can technically configure an interface with a 2001:db8:: address, but you will break things. Every conformant BGP filter drops 2001:db8::/32 at the edge, every IRR checker flags it as a bogon, and any AUP-respecting ISP refuses to route it. It exists purely for examples. Use ULA (fc00::/7) or a real prefix from your RIR instead.

Are there IPv4 documentation ranges older than RFC 5737?

Yes — 192.0.2.0/24 was originally reserved in the 1990s. RFC 5737 added 198.51.100.0/24 and 203.0.113.0/24 in 2010 because a single /24 was not enough to show multi-subnet examples. Earlier RFCs sometimes used real (now re-allocated) addresses in examples, which is exactly the confusion RFC 5737 was meant to stop.

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