computer science

List of assigned /8 IPv4 address blocks

List of assigned /8 IPv4 address blocks is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand List of assigned /8 IPv4 address blocks rather than just read about it. In short: Some large /8 blocks of IPv4 addresses, the former Class A network blocks, are assigned in whole to single organizations or related groups of organizations, either by the Internet Corporation for Assigned Names and Numbers (ICANN), through the Internet Assigned Numbers Authority (IANA), or a regional Internet registry. Each /8 block contains 2563 = 224 = 16,777,216 addresses, which covers the whole range of the last…

Key takeaways

List of assigned /8 IPv4 address blocks belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect List of assigned /8 IPv4 address blocks to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of List of assigned /8 IPv4 address blocks from memory before moving on to harder problems.

Reference excerpt

Some large /8 blocks of IPv4 addresses, the former Class A network blocks, are assigned in whole to single organizations or related groups of organizations, either by the Internet Corporation for Assigned Names and Numbers (ICANN), through the Internet Assigned Numbers Authority (IANA), or a regional Internet registry. Each /8 block contains 2563 = 224 = 16,777,216 addresses, which covers the whole range of the last three delimited segments of an IP address. This means that 256 /8 address blocks fit into the entire IPv4 space. As IPv4 address exhaustion has advanced to its final stages, some organizations, such as Stanford University, formerly using 36.0.0.0/8, have returned their allocated blocks (in this case to APNIC) to assist in the delay of the exhaustion date.

List of reserved /8 blocks

List of /8 blocks assigned to commercial organizations

List of /8 blocks assigned to the United States Department of Defense

List of /8 blocks assigned to the regional Internet registries

The regional Internet registries (RIRs) allocate IPs within a particular region of the world.

Note that this list may not include current assignments of /8 blocks to all regional or national Internet registries.

Original list of IPv4 assigned address blocks The original list of IPv4 address blocks was published in September 1981. In previous versions of the document, 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 relevant portion of RFC 790 is reproduced here with minor changes:

000.rrr.rrr.rrr Reserved [JBP] 001.rrr.rrr.rrr BBN-PR BBN Packet Radio Network [DCA2] 002.rrr.rrr.rrr SF-PR-1 SF Packet Radio Network [JEM] 003.rrr.rrr.rrr BBN-RCC BBN RCC Network [SGC] 004.rrr.rrr.rrr SATNET Atlantic Satellite Network [DM11] 005.rrr.rrr.rrr SILL-PR Ft. Sill Packet Radio Network[JEM] 006.rrr.rrr.rrr SF-PR-2 SF Packet Radio Network [JEM] 007.rrr.rrr.rrr CHAOS MIT CHAOS Network [MOON] 008.rrr.rrr.rrr CLARKNET SATNET subnet for Clarksburg [DM11] 009.rrr.rrr.rrr BRAGG-PR Ft. Bragg Packet Radio Net [JEM] 010.rrr.rrr.rrr ARPANET ARPANET [VGC] 011.rrr.rrr.rrr UCLNET University College London [PK] 012.rrr.rrr.rrr CYCLADES CYCLADES [VGC] 013.rrr.rrr.rrr Unassigned [JBP] 014.rrr.rrr.rrr TELENET TELENET [VGC] 015.rrr.rrr.rrr EPSS British Post Office EPSS [PK] 016.rrr.rrr.rrr DATAPAC DATAPAC [VGC] 017.rrr.rrr.rrr TRANSPAC TRANSPAC [VGC] 018.rrr.rrr.rrr LCSNET MIT LCS Network [DDC2] 019.rrr.rrr.rrr TYMNET TYMNET [VGC] 020.rrr.rrr.rrr DC-PR D.C. Packet Radio Network [VGC] 021.rrr.rrr.rrr EDN DCEC EDN [EC5] 022.rrr.rrr.rrr DIALNET DIALNET [MRC] 023.rrr.rrr.rrr MITRE MITRE Cablenet [APS] 024.rrr.rrr.rrr BBN-LOCAL BBN Local Network [SGC] 025.rrr.rrr.rrr RSRE-PPSN RSRE / PPSN [BD2] 026.rrr.rrr.rrr AUTODIN-II AUTODIN II [EC5] 027.rrr.rrr.rrr NOSC-LCCN NOSC / LCCN [KTP] 028.rrr.rrr.rrr WIDEBAND Wide Band Satellite Network [CJW2] 029.rrr.rrr.rrr DCN-COMSAT COMSAT Dist. Comp. Network [DLM1] 030.rrr.rrr.rrr DCN-UCL UCL Dist. Comp. Network [PK] 031.rrr.rrr.rrr BBN-SAT-TEST BBN SATNET Test Network [DM11] 032.rrr.rrr.rrr UCL-CR1 UCL Cambridge Ring 1 [PK] 033.rrr.rrr.rrr UCL-CR2 UCL Cambridge Ring 2 [PK] 034.rrr.rrr.rrr MATNET Mobile Access Terminal Net [DM11] 035.rrr.rrr.rrr NULL UCL/RSRE Null Network [BD2] 036.rrr.rrr.rrr SU-NET Stanford University Ethernet [MRC] 037.rrr.rrr.rrr DECNET Digital Equipment Network [DRL] 038.rrr.rrr.rrr DECNET-TEST Test Digital Equipment Net [DRL] 039.rrr.rrr.rrr SRINET SRI Local Network [GEOF] 040.rrr.rrr.rrr CISLNET CISL Multics Network [CH2] 041.rrr.rrr.rrr BBN-LN-TEST BBN Local Network Testbed [KTP] 042.rrr.rrr.rrr S1NET LLL-S1-NET [EAK] 043.rrr.rrr.rrr INTELPOST COMSAT INTELPOST [DLM1] 044.rrr.rrr.rrr AMPRNET Amateur Radio Experiment Net [HM]

See also Classless Inter-Domain Routing (CIDR) List of countries by IPv4 address allocation Top organizations by IPv4 address space Top ASNs by IPv4 address space

Notes

References "IANA IPv4 Address Space Registry". Internet Assigned Numbers Authority (IANA). 21 December 2017. Retrieved 22 December 2017. The authoritative up-to-date list of IANA assignments. "ARIN Whois Database". American Registry for Internet Numbers (ARIN). Retrieved 27 March 2011. Historical IP address lists: "INTERNET PROTOCOL ADDRESS SPACE". Internet Assigned Numbers Authority (IANA). October 2000. Archived from the original on 18 October 2000. Retrieved 27 March 2011. First version of IANA table with historical notes via the Internet Archive Wayback Machine. "Internet Protocol v4 Address Space". Internet Assigned Numbers Authority (IANA). September 2007. Archived from the original on 28 October 2007. Retrieved 27 March 2011. Last version of IANA table with historical notes via the Internet Archive Wayback Machine. Turtschi, Adrian (13 September 1999). "Complete List of Class A and Class B Networks". Adrian Turtschi. Retrieved 27 March 2011. Rogers, Paul (November 1999). "IP INDEX Encyclopedia". flumps.org. Archived from the original on 14 April 2001. Retrieved 27 March 2011. "IPv4 Addresses – the Complete Class A List". Infocellar. 5 April 2003. Archived from the original on 17 April 2011. Retrieved 27 March 2011. "INTERNET PROTOCOL V4 ADDRESS SPACE". DonkBoy Internet. 30 June 2005. Retrieved 27 March 2011. Cromwell, Bob (13 November 2008). "The /8 or Class A Networks". Bob Cromwell. Archived from the original on 17 December 2010. Retrieved 27 March 2011. Huston, Geoff (29 August 2005). "Report on the IANA IPv4 Address Registry". The Internet Society. Retrieved 27 March 2011. Huston, Geoff (July 2003). "IANA IPv4 Address Registry – Current Issues". CIDR Report. Retrieved 27 March 2011. "Global Policy for the Allocation of the Remaining IPv4 Address Space". Internet Corporation for Assigned Names and Numbers (ICANN). 6 March 2009. Retrieved 27 March 2011.

Worked examples

Example 1 — a first encounter with List of assigned /8 IPv4 address blocks

Start with the simplest possible case. Write down what List of assigned /8 IPv4 address blocks claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to List of assigned /8 IPv4 address blocks before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about List of assigned /8 IPv4 address blocks ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of List of assigned /8 IPv4 address blocks

In research: List of assigned /8 IPv4 address blocks appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses List of assigned /8 IPv4 address blocks in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: List of assigned /8 IPv4 address blocks is common in secondary-school and first-year university syllabi. It links to neighbouring topics IPv4, Internet-related lists, Network addressing, so understanding it makes those chapters shorter.
In everyday life: Look for List of assigned /8 IPv4 address blocks outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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Read the reference excerpt below once, without taking notes.
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Frequently asked questions

What is List of assigned /8 IPv4 address blocks in simple terms?

Why does List of assigned /8 IPv4 address blocks matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study List of assigned /8 IPv4 address blocks?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on List of assigned /8 IPv4 address blocks.