List of assigned /8 IPv4 address blocks explained

Some large 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 block contains 256 = 2 = 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, have returned their allocated blocks (in this case to APNIC) to assist in the delay of the exhaustion date.

List of reserved /8 blocks

See also: Reserved IP addresses.

Block Organization IANA date RIR date Notes
0.0.0.0/8 IANALocal Identification 1981-09 Originally IANAReserved 1981-09. 0.0.0.0/8 reserved for self-identification.
10.0.0.0/8 IANAPrivate Use 1995-06 Reserved for Private Networks. Formerly ARPANET.
127.0.0.0/8 IANALoopback 1981-09 127.0.0.0/8 is reserved for loopback.
224.0.0.0/8–239.0.0.0/8 1981-09 1991-05-22 Multicast (formerly "Class D") registered in https://www.iana.org/assignments/multicast-addresses.
240.0.0.0/8–255.0.0.0/8 Future Use 1981-09 Reserved for future use (formerly "Class E"). 255.255.255.255 is reserved for "limited broadcast" destination address.

List of assigned /8 blocks to commercial organisations

Block Organization IANA date RIR date Notes
12.0.0.0/8 1995-06 1983-08-23 Originally AT&T Bell Laboratories, but retained by AT&T when Bell Labs was spun off to Lucent Technologies in 1996. Assignment administered by ARIN (Legacy space)
17.0.0.0/8 1992-07 1990-04-16 Assignment administered by ARIN (Legacy space)
19.0.0.0/8 1995-05 1988-06-15 Assignment administered by ARIN (Legacy space)
38.0.0.0/8 1994-09 1991-04-16 Formerly PSINet. Assignment administered by ARIN (Legacy space)
53.0.0.0/8Mercedes-Benz Group AG1993-101970-01-01Assignment administered by RIPE (Legacy space)
73.0.0.0/8 Comcast Corporation[1] N/A 2005-04-19 Assignment administered by ARIN.

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

Block Organization IANA date RIR date Notes
6.0.0.0/8 1994-02 1994-02-01 Headquarters, USAISC
7.0.0.0/8 1995-04 1997-11-24 Formerly IANA - Reserved 1995-04.
Entirely assigned to DoD Network Information Center (DNIC) 1997-11-24.
Updated to Administered by ARIN not before 2007.
11.0.0.0/8 DoD Intel Information Systems 1993-05 1984-01-19
21.0.0.0/8 1991-07 1991-07-01 DoD Network Information Center (DNIC)
22.0.0.0/8 Defense Information Systems Agency1993-05 1989-06-26 DoD Network Information Center (DNIC)
26.0.0.0/8 Defense Information Systems Agency1995-05 1995-05-01 DoD Network Information Center (DNIC)
28.0.0.0/8 1992-07 DoD Network Information Center (DNIC)
29.0.0.0/8 Defense Information Systems Agency1991-07 1991-07-01 DoD Network Information Center (DNIC)
30.0.0.0/8 Defense Information Systems Agency1991-07 1991-07-01 DoD Network Information Center (DNIC)
33.0.0.0/8 1991-01 1991-01-01 DoD Network Information Center (DNIC)
55.0.0.0/8 1995-04 1996-10-26 Headquarters, USAISC. Formerly Boeing Computer Services 1995-04.
Updated to DoD Network Information Center in 2007-02.
214.0.0.0/8 US-DOD 1998-03 1998-03-27 DoD Network Information Center (DNIC)
215.0.0.0/8 US-DOD 1998-03 1998-06-05 DoD Network Information Center (DNIC)

List of assigned /8 blocks to the regional Internet registries

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

Block Organization IANA date RIR date Notes
1.0.0.0/8 2010-01 Formerly IANA - reserved 1981-09.
2.0.0.0/8 2009-10 Formerly IANA - reserved 1981-09.
3.0.0.0/8ARIN1994-05Amazon.com.[2] Formerly General Electric Company.
4.0.0.0/8ARIN1992-12Various registries (maintained by ARIN). Formerly Bolt Beranek and Newman Inc., then GTE, then Genuity, then Level 3 Communications, Inc.
5.0.0.0/8 2010-11 Formerly IANA - reserved 1995-07.
8.0.0.0/8ARIN1992-121992-12-01Various registries (maintained by ARIN). Formerly Bolt Beranek and Newman Inc., then GTE, then Genuity, then Level 3 Communications, Inc.
9.0.0.0/8ARIN1992-08IBM except for 9.9.9.0/24, which is Quad9.
13.0.0.0/8ARIN1991-09Various registries (maintained by ARIN). Formerly Xerox.
14.0.0.0/8 2010-04 Starting 1991-06-01, was used to map Public Data Network (X.121) addresses to IP addresses. Returned to IANA 2008-01-22. This network was reclaimed by IANA in 2007 and was subsequently re-allocated in 2010. See RFC 877 and RFC 1356 for historical information.[3]
15.0.0.0/8ARIN1991-09Various registries (maintained by ARIN). Formerly Hewlett-Packard Company. HP Inc still uses a portion of the block.
16.0.0.0/8ARIN1994-111989-05-18Various registries (maintained by ARIN). Formerly Digital Equipment Corporation, then Compaq, then Hewlett-Packard.
18.0.0.0/8ARIN1994-01Various registries (maintained by ARIN). Formerly MIT.
20.0.0.0/8ARIN1994-10Various registries (maintained by ARIN). Formerly DXC Technology. Computer Sciences Corporation, who owned this block, merged with HP Enterprise Services to create DXC Technology on 3 April 2017.[4] [5]
23.0.0.0/8 2010-11 Formerly IANA - reserved 1995-07.
24.0.0.0/8 2001-05 2001-05-01 Formerly IANA - Cable Block 1995-07, then ARIN - Cable Block 2001-05.[6] Updated to ARIN not before 2007.
25.0.0.0/8 1995-011995-01 1985-01-28 Originally Royal Signals and Radar Establishment. Updated to UK Ministry of Defence in 2006-01. -->
27.0.0.0/8 2010-01 Formerly IANA - reserved 1995-04.
31.0.0.0/8 2010-05 2010-05-18 Formerly IANA - reserved 1991-04.
32.0.0.0/8ARIN1994-06Various registries (maintained by ARIN). Formerly AT&T Global Network Services. Originally Norsk Informasjonsteknologi (at that time maintained by RIPE NCC). IBM acquired Norsk Informasjonsteknologi (Norway) in 1995.
34.0.0.0/8ARIN1993-03Various registries (maintained by ARIN). Formerly Halliburton Company.
35.0.0.0/8 1994-04 2012-08 Various registries (Maintained by ARIN). Formerly Merit Network 1986.
36.0.0.0/8 2010-10 Formerly Stanford University 1993-04, then IANA - Reserved 2000-07.
37.0.0.0/8 2010-11 Formerly IANA - Reserved 1995-04.
39.0.0.0/8 2011-01 Formerly IANA - Reserved 1995-04.
40.0.0.0/8ARIN1994-06Various registries (Maintained by ARIN).
41.0.0.0/8 2005-04 Formerly IANA - Reserved 1995-05.
42.0.0.0/8 2010-10 Formerly IANA - Reserved 1995-07.
43.0.0.0/8 1991-01 1989-02-21 Various registries (Maintained by APNIC). Originally Japan Inet 1991-01 (IANA date) or 1989-02-21 (RIR date). Administered by APNIC not before 2007.
1992-07 2019-07-18 Various registries (Maintained by ARIN). Originally Amateur Radio Digital Communications. was sold to Amazon on 2019-07-18.[7]
45.0.0.0/8 1995-01 1991-09-09 Various registries (Maintained by ARIN). Formerly Interop Show Network 1995-01 or 1991-09-09 (RIR date). Returned to ARIN in 2010-10 except a /15 block. In 2011 it became available for distribution (or possibly be returned to the IANA, depending on the global policy in effect at that time).[8]
46.0.0.0/8 2009-09 Formerly Bolt Beranek and Newman Inc. 1992-12. Returned to IANA in 2007-04.[9] Updated to IANA - Reserved in 2007-04.
47.0.0.0/8 1991-01Various registries (Maintained by ARIN). Formerly Bell-Northern Research, which became Northern Telecom, aka, Nortel, until its demise, circa 2010.
48.0.0.0/8 2023-10-02 1990-12-07 Assignment administered by ARIN (Legacy space). Formerly Prudential Financial, who still use a portion of the space.
49.0.0.0/8 2010-08 Formerly Joint Technical Command (Returned to IANA Mar 98) 1994-05. Updated to IANA - Reserved in 2007-05.
50.0.0.0/8 2010-02 Formerly Joint Technical Command (Returned to IANA Mar 98) 1994-05. Updated to IANA - Reserved in 2007-05.
51.0.0.0/8 1994-08Various registries (Maintained by RIPE NCC). Formerly UK Government Department for Work and Pensions. 1994-08 1991-09-16 -->
52.0.0.0/8ARIN1991-12Formerly DuPont.
54.0.0.0/8ARIN1992-03Various registries (Maintained by ARIN).1993-10 1992-03-17 Cap Debis CCS (Daimler AG). -->
56.0.0.0/8 1992-11Formerly United States Postal Service.
57.0.0.0/8 1995-05Formerly SITA. 57.0.0.0/8 1995-05 1993-06-21 " in a different section of this document. -->
58.0.0.0/8APNIC2004-04
59.0.0.0/8APNIC2004-04
60.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
61.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
62.0.0.0/8RIPE NCC1997-04
63.0.0.0/8ARIN1997-04
64.0.0.0/8ARIN1999-07
65.0.0.0/8ARIN2000-07
66.0.0.0/8ARIN2000-07
67.0.0.0/8ARIN2001-05
68.0.0.0/8ARIN2001-06
69.0.0.0/8ARIN2002-08
70.0.0.0/8ARIN2004-01
71.0.0.0/8ARIN2004-08
72.0.0.0/8ARIN2004-08
74.0.0.0/8ARIN2005-06
75.0.0.0/8ARIN2005-06
76.0.0.0/8ARIN2005-06
77.0.0.0/8RIPE NCC2006-08
78.0.0.0/8RIPE NCC2006-08
79.0.0.0/8RIPE NCC2006-08
80.0.0.0/8RIPE NCC2001-04
81.0.0.0/8RIPE NCC2001-04
82.0.0.0/8RIPE NCC2002-11
83.0.0.0/8RIPE NCC2003-11
84.0.0.0/8RIPE NCC2003-11
85.0.0.0/8RIPE NCC2004-04
86.0.0.0/8RIPE NCC2004-04
87.0.0.0/8RIPE NCC2004-04
88.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
89.0.0.0/8RIPE NCC2005-06
90.0.0.0/8RIPE NCC2005-06Except for 90.0.0.0/9, which is Orange
91.0.0.0/8RIPE NCC2005-06
92.0.0.0/8RIPE NCC2007-03
93.0.0.0/8RIPE NCC2007-03
94.0.0.0/8RIPE NCC2007-07
95.0.0.0/8RIPE NCC2007-07
96.0.0.0/8ARIN2006-10
97.0.0.0/8ARIN2006-10
98.0.0.0/8ARIN2006-10
99.0.0.0/8ARIN2006-10
100.0.0.0/8ARIN2010-11100.64.0.0/10 reserved for Carrier-grade NAT (detailed in).
101.0.0.0/8APNIC2010-08
102.0.0.0/8AFRINIC2011-02
103.0.0.0/8APNIC2011-02
104.0.0.0/8ARIN2011-02
105.0.0.0/8AFRINIC2010-11
106.0.0.0/8APNIC2011-01
107.0.0.0/8ARIN2010-02
108.0.0.0/8ARIN2008-12
109.0.0.0/8RIPE NCC2009-01
110.0.0.0/8APNIC2008-11
111.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
112.0.0.0/8APNIC2008-05
113.0.0.0/8APNIC2008-05
114.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
115.0.0.0/8APNIC2007-10
116.0.0.0/8APNIC2007-01
117.0.0.0/8APNIC2007-01
118.0.0.0/8APNIC2007-01
119.0.0.0/8APNIC2007-01
120.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
121.0.0.0/8APNIC2006-01
122.0.0.0/8APNIC2006-01
123.0.0.0/8APNIC2006-01
124.0.0.0/8APNIC2005-01
125.0.0.0/8APNIC2005-01
126.0.0.0/8APNIC2005-01SOFTBANK Corp.
128.0.0.0/8 1993-05Various registries (Maintained by ARIN). 128.0.0.0 is the start address of formerly "Class B".
129.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
130.0.0.0/8Various registries
131.0.0.0/8Various registries
132.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
133.0.0.0/8APNIC1997-03JPNIC[10]
134.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
135.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
136.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
137.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
138.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
139.0.0.0/8MIXVarious registries
140.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
141.0.0.0/8RIPE NCC1993-05Various registries (Maintained by RIPE NCC).
142.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
143.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
144.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
145.0.0.0/8RIPE NCC1993-05Various registries (Maintained by RIPE NCC).
146.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
147.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
148.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
149.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
150.0.0.0/8APNIC1993-05Various registries (Maintained by APNIC).
151.0.0.0/8RIPE NCC1993-05Various registries (Maintained by RIPE NCC).
152.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
153.0.0.0/8APNIC1993-05Various registries (Maintained by APNIC).
154.0.0.0/8AFRINIC1993-05Various registries (Maintained by AFRINIC).
155.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
156.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
157.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
158.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
159.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
160.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
161.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
162.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
163.0.0.0/8APNIC1993-05Various registries (Maintained by APNIC).
164.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
165.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
166.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
167.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
168.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
169.0.0.0/8 1993-05 1993-05-01 Various registries (Maintained by ARIN). 169.254.0.0/16 (169.254.0.0–169.254.255.255) reserved for link-local addressing (RFC 6890).
170.0.0.0/8ARIN1993-05Various registries (Maintained by ARIN).
171.0.0.0/8APNIC1993-05Various registries (Maintained by APNIC).
172.0.0.0/8 1993-05 1993-05-01 Various registries (Maintained by ARIN). 172.16.0.0/12 (172.16.0.0–172.31.255.255) reserved for private networks (RFC 1918).
173.0.0.0/8ARIN2008-02
174.0.0.0/8ARIN2008-02
175.0.0.0/8APNIC2009-08
176.0.0.0/8RIPE NCC2010-05
177.0.0.0/8 2010-06
178.0.0.0/8RIPE NCC2009-01Various registries (Maintained by RIPE NCC).
179.0.0.0/8 2011-02
180.0.0.0/8APNIC2009-04
181.0.0.0/8 2010-06
182.0.0.0/8APNIC2009-08
183.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
184.0.0.0/8ARIN2008-12
185.0.0.0/8RIPE NCC2011-02Various registries (Maintained by RIPE NCC).
186.0.0.0/8 2007-09
187.0.0.0/8 2007-09
188.0.0.0/8RIPE NCC1993-05Various registries (Maintained by RIPE NCC).
189.0.0.0/8 1995-06
190.0.0.0/8 1995-06
191.0.0.0/8 1993-05 Various registries (Maintained by LACNIC).
192.0.0.0/8 1993-05 1993-05-01 Various registries (Maintained by ARIN). 192.0.2.0/24 reserved for TEST-NET-1 (RFC 5737). 192.88.99.0/24 reserved for 6to4 Relay Anycast (RFC 3068). 192.168.0.0/16 (192.168.0.0–192.168.255.255) reserved for private networks (RFC 1918). 192.0.0.0/24 reserved for IANA IPv4 Special Purpose Address Registry (RFC 5736). 192.0.0.0 is the start address of formerly "Class C".
193.0.0.0/8RIPE NCC1993-05
194.0.0.0/8RIPE NCC1993-05
195.0.0.0/8RIPE NCC1993-05
196.0.0.0/8AFRINIC1993-05Various registries (Maintained by AFRINIC).
197.0.0.0/8AFRINIC2008-10
198.0.0.0/8 1993-05 Various registries (Maintained by ARIN). 198.18.0.0/15 reserved for Network Interconnect Device Benchmark Testing (RFC 6890). 198.51.100.0/24 reserved for TEST-NET-2 (RFC 5737).
199.0.0.0/8ARIN1993-05
200.0.0.0/8 2002-11
201.0.0.0/8 2003-04
202.0.0.0/8 2009-10 Various registries (Maintained by APNIC). 202.123.0.0/19 transferred to AFRINIC
203.0.0.0/8 1993-05 203.0.113.0/24 reserved for TEST-NET-3 (RFC 5737).
204.0.0.0/8ARIN1994-03
205.0.0.0/8ARIN1994-03
206.0.0.0/8ARIN1995-04
207.0.0.0/8ARIN1995-11
208.0.0.0/8ARIN1996-04
209.0.0.0/8ARIN1996-06
210.0.0.0/8APNIC1996-06
211.0.0.0/8APNIC1996-06
212.0.0.0/8RIPE NCC1997-10
213.0.0.0/8RIPE NCC1993-10
216.0.0.0/8ARIN1998-04
217.0.0.0/8 2000-06 2002-06-25
218.0.0.0/8 2010-01 Formerly IANA - Reserved 1981-09.
219.0.0.0/8APNIC2001-09
220.0.0.0/8APNIC2001-12
221.0.0.0/8APNIC2002-07
222.0.0.0/8APNIC2003-02
223.0.0.0/8APNIC2010-04

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:

See also

References

Notes and References

  1. Web site: Whois-RWS .
  2. Web site: Tell HN: Amazon now owns 3.0.0.0/8 . Hacker News.
  3. Web site: Public Data Network Numbers . 24 June 2010 . . 27 March 2011.
  4. Web site: CSC Announces Merger with Enterprise Services Segment of Hewlett Packard Enterprise to create a Global IT Services Leader. 24 May 2016. Press release. 4 November 2016.
  5. Web site: New York Stock Exchange DXC Technology . www.nyse.com . dead . https://web.archive.org/web/20170406022954/https://www.nyse.com/network/article/nyse-dxc . 2017-04-06.
  6. Web site: Network 24 - Cable Block . 11 May 2001 . . 27 March 2011 . dead . https://web.archive.org/web/20110627053427/https://www.iana.org/assignments/network-24 . 27 June 2011 .
  7. Web site: AMPRNet | Amateur Radio Digital Communications .
  8. Web site: IPv4 IANA Free Pool Depletion – FAQ . . 27 March 2011 . https://web.archive.org/web/20110628195409/https://www.arin.net/resources/request/ipv4_depletion.html . 28 June 2011 . dead .
  9. van Beijnum . Iljitsch . The Internet Protocol Journal . September 2007 . IPv4 Address Space: 2.46 Billion Down, 1.25 Billion to Go . 10 . 3 . 2024-04-20 . 22-28 . 1944-1134.
  10. Web site: 133.0.0.0/8 Japan Network Information Center Prefix BGP Network Information - BGPView. 2022-01-25. bgpview.io.

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