Give each example network its own range
01Three reserved IPv4 blocks let a document distinguish separate networks without borrowing someone else’s addresses.
All three networks are documentation fixtures. Their use needs no registry coordination, but they are not assigned to an end user or organization.
Source for this drawing: RFC 5737 · Read RFC section 3 ↗
New to this? Start hereA quick picture + helpful background
A message needs an address.
Think of a packet as a small addressed envelope. Devices pass it onward; transport protocols decide what delivery promises an application gets.
Helpful first, if these ideas are unfamiliar
These pictures are analogies to help you learn. The linked RFC explains the actual rules.
Terms in this drawing
Related RFCs and changes
“Updates” changes part of an earlier RFC. “Obsoletes” replaces it. This list shows selected related documents.
Use the named documentation ranges when writing IPv4 examples.
- The blocks are 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).
- Use in documentation needs no coordination with the Internet Assigned Numbers Authority (IANA) or an Internet registry.
- These addresses are not assigned to an end user or organization. A written example does not grant an address assignment.
Examples are documentation text, not a network configuration. No packets are sent. SHOULD and SHOULD NOT are recommendations, not MUST. Valid exceptions require understanding and carefully weighing the full implications (RFC 2119 §§3–4).
Read the RFC section ↗