Update to the IPv4 Registry Format and Content

21 February 2008

IANA has improved the format for the IPv4 Address Space registry. At the same time, the entries that were marked “Various Registries” have been replaced with references to the Regional Internet Registry (RIR) that provides WHOIS and reverse DNS service for that /8 allocation.

If you want to machine-process the IPv4 registry, the new fields are:

where the Date will always be of the form “YYYY-MM” and the status has the following possible values:


/8 allocations that contain legacy assignments in them that are now managed by the RIRs have the text “Administered by” in the Designation column. Legacy assignments refer to IP address allocations made before the RIR system was established.

Reserved address space held by IANA does not have a date listed.

The registry can be found at:


If you have questions about the structure of the new format, please send e-mail to iana@iana.org.