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240.0.0.0/4

240.0.0.0/4 is reserved for future use and not used on the internet.

Last updated 2 Nov 2026 from the IANA IPv4 Special-Purpose Address Registry

Short answer

240.0.0.0/4 is reserved for future use and not used on the internet.

Block240.0.0.0/4
First – last240.0.0.0 – 255.255.255.255
Size268,435,456 addresses
Name in the registryReserved
Defined inRFC 1112, Section 4
Allocated1989-08
Valid as source / destinationFalse / False
ForwardableFalse
Globally reachableFalse

What it means

RFC 1112 marked 240.0.0.0/4 (“class E”) as reserved. Many systems refuse to use it at all.

255.255.255.255, at the top of this range, is the limited broadcast address that reaches every device on the local network.

Want the address websites actually see for you? Open the Truth Check.

Sources

  1. IANA IPv4 Special-Purpose Address Registry (CC0) · checked 2 Nov 2026
  2. RFC 1112