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This is a list of countries by IPv4 address allocation. The Internet Assigned Numbers Authority (IANA) distributes large blocks of addresses to regional Internet registries (RIRs), which then assign them to national Internet registries and local Internet registries within their respective service regions. [ 1 ]
The original list of IPv4 address blocks was published in September 1981. [3] In previous versions of the document, [19] [20] network numbers were 8-bit numbers rather than the 32-bit numbers used in IPv4. At that time, three networks were added that were not listed earlier: 42.rrr.rrr.rrr, 43.rrr.rrr.rrr, and 44.rrr.rrr.rrr.
The sortable table below contains the three sets of ISO 3166-1 country codes for each of its 249 countries, links to the ISO 3166-2 country subdivision codes, and the Internet country code top-level domains (ccTLD) which are based on the ISO 3166-1 alpha-2 standard with the few exceptions noted. See the ISO 3166-3 standard for former country codes.
Used for local communications within a private network [3] 100.64.0.0/10 100.64.0.0–100.127.255.255 4 194 304: Private network Shared address space [4] for communications between a service provider and its subscribers when using a carrier-grade NAT: 127.0.0.0/8 127.0.0.0–127.255.255.255 16 777 216: Host Used for loopback addresses to the ...
IP addresses are assigned to a host either dynamically as they join the network, or persistently by configuration of the host hardware or software. Persistent configuration is also known as using a static IP address. In contrast, when a computer's IP address is assigned each time it restarts, this is known as using a dynamic IP address.
Version: 4 bits The first header field in an IP packet is the Version field. For IPv4, this is always equal to 4. Internet Header Length (IHL): 4 bits The IPv4 header is variable in size due to the optional 14th field (Options). The IHL field contains the size of the IPv4 header; it has 4 bits that specify the number of 32-bit words in the header.
This is a list of the IP protocol numbers found in the field Protocol of the IPv4 header and the Next Header field of the IPv6 header. It is an identifier for the encapsulated protocol and determines the layout of the data that immediately follows the header.
The first two rows show that 3 of the entered addresses are in a /33 range, while 72 are in a /64. Blocking the /33 would affect 2G /64, that is, over 2 billion /64 allocations, but would block only 3 of the given addresses.