Replace a misleading historical example
05128.66.0.0/16 appeared in older examples, but RFC 5737 explains that this did not reserve it.
TEST-NET-2 is reserved for documentation. No end party is assigned it. The old range’s current assignment is not determined by the fact that an old example mentioned it.
Source for this drawing: RFC 5737 · Read RFC section 5 ↗
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.
Past example use does not create a documentation reservation.
- RFC 5737 says 128.66.0.0/16 is not reserved for any special purpose and can be used for regular assignments with caution.
- Do not infer current ownership or reachability from this historical discussion.
- For a new IPv4 documentation example, choose one of the three TEST-NET blocks; this changes the document, not a live network.
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 ↗