192.0.2.0/24 — the address you write in docs
192.0.2.0/24 is TEST-NET-1, reserved by RFC 5737 for one purpose: appearing in examples. Its 256 addresses (192.0.2.0–192.0.2.255) are guaranteed never to be allocated to anyone, which makes them the only safe public-looking addresses to print in documentation, tutorials, config snippets and vendor whitepapers.
It has two siblings sharing the same job: 198.51.100.0/24 (TEST-NET-2) and 203.0.113.0/24 (TEST-NET-3). When an example needs two networks talking to each other, authors typically spend one TEST-NET per side.
| Range start | 192.0.2.0 |
| Range end | 192.0.2.255 |
| Subnet mask | 255.255.255.0 |
| Wildcard mask | 0.0.0.255 |
| Total addresses | 256 |
TEST-NET-1 is reserved for documentation (RFC 5737) and never assigned — the table shows the block's extent; network/broadcast roles are theoretical here.
Why examples need reserved addresses
Before RFC 5737 (2010), docs used made-up or real addresses, and both failed badly: readers copy-pasted configs pointing at actual production networks, and placeholder domains like example.com have no IP equivalent. If you have seen a tutorial use 1.1.1.1 as a fake server address — that is now Cloudflare's very real DNS resolver — you know why a reserved block matters.
The guarantee is the point: IANA will never delegate these ranges, so a packet sent to 192.0.2.1 goes nowhere, today and forever. Copy-paste away; the worst outcome is a black hole.
Using it well
Reach for TEST-NET whenever prose needs a plausible public address: firewall examples, DNS zone files, "connect to 203.0.113.10" walkthroughs. For the internal side of an example, pair it with RFC 1918 space. And on the filtering side, all three TEST-NETs are bogons — drop them at the edge like any other unroutable block.
CIDR Calculator
Run the math on 192.0.2.0/24 — or any other block
Frequently asked questions
What is 192.0.2.1 used for?
Nothing — and that is the point. 192.0.2.0/24 is TEST-NET-1 (RFC 5737), reserved for documentation and examples so writers can use realistic public-style addresses that never belong to a real host.
Is 192.0.2.0/24 routable?
No. It is reserved and permanently unallocated; networks should drop it as a bogon, and any traffic toward it blackholes.
What are the TEST-NET ranges?
Three /24s from RFC 5737: 192.0.2.0/24 (TEST-NET-1), 198.51.100.0/24 (TEST-NET-2) and 203.0.113.0/24 (TEST-NET-3) — all reserved for examples, none ever assigned.
Why do I see 203.0.113.x in config examples?
Because it is TEST-NET-3, the third documentation block. Authors spread scenarios across the three TEST-NETs when an example needs several distinct networks.