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Global Policy for Post Exhaustion IPv4 Allocation Mechanisms by the IANA | (Ratified 6 May 2012)

The IANA shall establish a Recovered IPv4 Pool to be utilized post RIR IPv4 exhaustion. The Recovered IPv4 Pool will initially contain any fragments that may be left over in the IANA. It will also hold any space returned to the IANA by any other means.

The Recovered IPv4 Pool will be administered by the IANA. It will contain:

  • Any fragments left over in the IANA inventory after the last /8s of IPv4 space are delegated to the RIRs
    • The IANA inventory excludes "Special use IPv4 addresses" as defined in BCP 153 and any addresses allocated by the IANA for experimental use.
  • Any IPv4 space returned to the IANA by any means.

The Recovered IPv4 Pool will stay inactive until the first RIR has less than a total of a /9 in its inventory of IPv4 address space.

When one of the RIRs declares it has less than a total of a /9 in its inventory, the Recovered IPv4 pool will be declared active, and IP addresses from the Recovered IPv4 Pool will be allocated as follows:

  • Allocations from the IANA may begin once the pool is declared active.
  • In each "IPv4 allocation period", each RIR will receive a single "IPv4 allocation unit" from the IANA.
  • An "IPv4 allocation period" is defined as a 6-month period following 1 March or 1 September in each year.
  • The IANA will calculate the size of the "IPv4 allocation unit" at the following times:
    • When the Recovered IPv4 Pool is first activated
    • At the beginning of each IPv4 allocation period
    • To calculate the "IPv4 allocation unit" at these times, the IANA will use the following formula:

      IPv4 allocation unit = 1/5 of Recovered IPv4 pool, rounded down to the next CIDR (power-of-2) boundary.

      No RIR may get more than this calculation used to determine the IPv4 allocation unit even when they can justify a need for it.

      The minimum "IPv4 allocation unit" size will be a /24. If the calculation used to determine the IPv4 allocation unit results in a block smaller than a /24, the IANA will not distribute any addresses in that IPv4 allocation period.

The IANA may make public announcements of IPv4 address transactions that occur under this policy. The IANA will make appropriate modifications to the "Internet Protocol V4 Address Space" page of the IANA website and may make announcements to its own appropriate announcement lists. The IANA announcements will be limited to which address ranges, the time of allocation, and to which Registry they have been allocated.

Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as"""" is not an IDN."