Class A, B, C and CIDR networks

Traditionally IP network is classified as A, B or C network. The computers identify the class by first 3 bits (A=000, B=100, C=110), while humans identify the class by first octet(8-bit) number. With scarcity of IP addresses, the class-based system has been replaced by ClasslessInter-DomainRouting (CIDR) to more efficiently allocate IP addresses.

Class Network Address Number of Hosts Netmask
/0 4,294,967,296 0.0.0.0
/1 2,147,483,648 128.0.0.0
/2 1,073,741,824 192.0.0.0
/3 536,870,912 224.0.0.0
/4 240,435,456 240.0.0.0
/5 134,217,728 248.0.0.0
/6 67,108,864 252.0.0.0
/7 33,554,432 254.0.0.0
A /8 16,777,216 255.0.0.0
/9 8,388,608 255.128.0.0
/10 4,194,304 255.192.0.0
/11 2,097,152 255.224.0.0
/12 1,048,576 255.240.0.0
/13 524,288 255.248.0.0
/14 262,144 255.252.0.0
/15 131,072 255.254.0.0
B /16 65,536 255.255.0.0
/17 32,768 255.255.128.0
/18 16,384 255.255.192.0
/19 8,192 255.255.224.0
/20 4,096 255.255.240.0
/21 2,048 255.255.248.0
/22 1,024 255.255.252.0
/23 512 255.255.254.0
C /24 256 255.255.255.0
/25 128 255.255.255.128
/26 64 255.255.255.192
/27 32 255.255.255.224
/28 16 255.255.255.240
/29 8 255.255.255.248
/30 4 255.255.255.252
/31 2 255.255.255.254
/32 1 255.255.255.255
IPv6 rangeblocks

IPv6 addresses are each 128 bits long. Because each digit in an IPv6 address can have 16 different values (from 0 to 15), each digit represents the overall value of 4 bits (one nibble), with 32 digits total. As with IPv4, CIDR notation describes ranges in terms of a common prefix of bits. For example 2001:db8::/32 means that the range described has the first 32 bits set to the binary digits 00100000000000010000110110101000. Also like IPv4, MediaWiki implements IPv6 rangeblocks using CIDR notation.

CIDR Start of range End of range Total addresses Total /64 subnets
::/0 :: ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 340,282,366,920,938,463,463,374,607,431,768,211,456 18,446,744,073,709,551,616
::/1 :: 7fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 170,141,183,460,469,231,731,687,303,715,884,105,728 9,223,372,036,854,775,808
::/2 :: 3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 85,070,591,730,234,615,865,843,651,857,942,052,864 4,611,686,018,427,387,904
2000::/3 2000:: 3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 42,535,295,865,117,307,932,921,825,928,921,026,432 2,305,843,009,213,693,452
2000::/4 2000:: 2fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 21,267,647,932,558,653,966,460,912,964,485,513,216 1,152,921,504,606,846,976
2000::/5 2000:: 27ff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 10,633,823,966,279,326,983,230,456,482,242,756,608 576,460,752,303,423,488
2000::/6 2000:: 23ff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 5,316,911,983,139,663,491,615,228,241,121,378,304 288,230,376,151,711,744
2000::/7 2000:: 21ff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 2,658,455,991,569,831,745,807,614,120,560,689,152 144,115,188,075,855,872
2000::/8 2000:: 20ff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 1,329,227,995,784,915,872,903,807,060,280,344,576 72,057,594,037,927,936
2000::/9 2000:: 207f:ffff:ffff:ffff:ffff:ffff:ffff:ffff 664,613,997,892,457,936,451,903,530,140,172,288 36,028,797,018,963,968
2000::/10 2000:: 203f:ffff:ffff:ffff:ffff:ffff:ffff:ffff 332,306,998,946,228,968,225,951,765,070,086,144 18,014,398,509,481,984
2000::/11 2000:: 201f:ffff:ffff:ffff:ffff:ffff:ffff:ffff 166,153,499,473,114,484,112,975,882,535,043,072 9,007,199,254,740,992
2000::/12 2000:: 200f:ffff:ffff:ffff:ffff:ffff:ffff:ffff 83,076,749,736,557,242,056,487,941,267,521,536 4,503,599,627,370,496
2000::/13 2000:: 2007:ffff:ffff:ffff:ffff:ffff:ffff:ffff 41,538,374,868,278,621,028,243,970,633,760,768 2,251,799,813,685,248
2000::/14 2000:: 2003:ffff:ffff:ffff:ffff:ffff:ffff:ffff 20,769,187,434,139,310,514,121,985,316,880,384 1,125,899,906,842,624
2000::/15 2000:: 2001:ffff:ffff:ffff:ffff:ffff:ffff:ffff 10,384,593,717,069,655,257,060,992,658,440,192 562,949,953,421,312
2001::/16 2001:: 2001:ffff:ffff:ffff:ffff:ffff:ffff:ffff 5,192,296,858,534,827,628,530,496,329,220,096 281,474,976,710,656
2001::/17 2001:: 2001:7fff:ffff:ffff:ffff:ffff:ffff:ffff 2,596,148,429,267,413,814,265,248,164,610,048 140,737,488,355,328
2001::/18 2001:: 2001:3fff:ffff:ffff:ffff:ffff:ffff:ffff 1,298,074,214,633,706,907,132,624,082,305,024 70,368,744,177,664
2001::/19 2001:: 2001:1fff:ffff:ffff:ffff:ffff:ffff:ffff 649,037,107,316,853,453,566,312,041,152,512 35,184,372,088,832
2001::/20 2001:: 2001:0fff:ffff:ffff:ffff:ffff:ffff:ffff 324,518,553,658,426,726,783,156,020,576,256 17,592,186,044,416
2001:800::/21 2001:800:: 2001:0fff:ffff:ffff:ffff:ffff:ffff:ffff 162,259,276,829,213,363,391,578,010,288,128 8,796,093,022,208
2001:c00::/22 2001:c00:: 2001:0fff:ffff:ffff:ffff:ffff:ffff:ffff 81,129,638,414,606,681,695,789,005,144,064 4,398,046,511,104
2001:c00::/23 2001:c00:: 2001:0dff:ffff:ffff:ffff:ffff:ffff:ffff 40,564,819,207,303,340,847,894,502,572,032 2,199,023,255,552
2001:d00::/24 2001:d00:: 2001:0dff:ffff:ffff:ffff:ffff:ffff:ffff 20,282,409,603,651,670,423,947,251,286,016 1,099,511,627,776
2001:d80::/25 2001:d80:: 2001:0dff:ffff:ffff:ffff:ffff:ffff:ffff 10,141,204,801,825,835,211,973,625,643,008 549,755,813,888
2001:d80::/26 2001:d80:: 2001:0dbf:ffff:ffff:ffff:ffff:ffff:ffff 5,070,602,400,912,917,605,986,812,821,504 274,877,906,944
2001:da0::/27 2001:da0:: 2001:0dbf:ffff:ffff:ffff:ffff:ffff:ffff 2,535,301,200,456,458,802,993,406,410,752 137,438,953,472
2001:db0::/28 2001:db0:: 2001:0dbf:ffff:ffff:ffff:ffff:ffff:ffff 1,267,650,600,228,229,401,496,703,205,376 68,719,476,736
2001:db8::/29 2001:db8:: 2001:0dbf:ffff:ffff:ffff:ffff:ffff:ffff 633,825,300,114,114,700,748,351,602,688 34,359,738,368
2001:db8::/30 2001:db8:: 2001:0dbb:ffff:ffff:ffff:ffff:ffff:ffff 316,912,650,057,057,350,374,175,801,344 17,179,869,184
2001:db8::/31 2001:db8:: 2001:0db9:ffff:ffff:ffff:ffff:ffff:ffff 158,456,325,028,528,675,187,087,900,672 8,589,934,592
2001:db8::/32 2001:db8:: 2001:db8:ffff:ffff:ffff:ffff:ffff:ffff 79,228,162,514,264,337,593,543,950,336 4,294,967,296
2001:db8::/33 2001:db8:: 2001:db8:7fff:ffff:ffff:ffff:ffff:ffff 39,614,081,257,132,168,796,771,975,168 2,147,483,648
2001:db8::/34 2001:db8:: 2001:db8:3fff:ffff:ffff:ffff:ffff:ffff 19,807,040,628,566,084,398,385,987,584 1,073,741,824
2001:db8::/35 2001:db8:: 2001:db8:1fff:ffff:ffff:ffff:ffff:ffff 9,903,520,314,283,042,199,192,993,792 536,870,912
2001:db8::/36 2001:db8:: 2001:db8:0fff:ffff:ffff:ffff:ffff:ffff 4,951,760,157,141,521,099,596,496,896 268,435,456
2001:db8::/37 2001:db8:: 2001:db8:07ff:ffff:ffff:ffff:ffff:ffff 2,475,880,078,570,760,549,798,248,448 134,217,728
2001:db8::/38 2001:db8:: 2001:db8:03ff:ffff:ffff:ffff:ffff:ffff 1,237,940,039,285,380,274,899,124,224 67,108,864
2001:db8::/39 2001:db8:: 2001:db8:01ff:ffff:ffff:ffff:ffff:ffff 618,970,019,642,690,137,449,562,112 33,554,432
2001:db8::/40 2001:db8:: 2001:db8:00ff:ffff:ffff:ffff:ffff:ffff 309,485,009,821,345,068,724,781,056 16,777,216
2001:db8::/41 2001:db8:: 2001:db8:007f:ffff:ffff:ffff:ffff:ffff 154,742,504,910,672,534,362,390,528 8,388,608
2001:db8::/42 2001:db8:: 2001:db8:003f:ffff:ffff:ffff:ffff:ffff 77,371,252,455,336,267,181,195,264 4,194,304
2001:db8::/43 2001:db8:: 2001:db8:001f:ffff:ffff:ffff:ffff:ffff 38,685,626,227,668,133,590,597,632 2,097,152
2001:db8::/44 2001:db8:: 2001:db8:000f:ffff:ffff:ffff:ffff:ffff 19,342,813,113,834,066,795,298,816 1,048,576
2001:db8::/45 2001:db8:: 2001:db8:0007:ffff:ffff:ffff:ffff:ffff 9,671,406,556,917,033,397,649,408 524,288
2001:db8::/46 2001:db8:: 2001:db8:0003:ffff:ffff:ffff:ffff:ffff 4,835,703,278,458,516,698,824,704 262,144
2001:db8::/47 2001:db8:: 2001:db8:0001:ffff:ffff:ffff:ffff:ffff 2,417,851,639,229,258,349,412,352 131,072
2001:db8::/48 2001:db8:: 2001:db8:0000:ffff:ffff:ffff:ffff:ffff 1,208,925,819,614,629,174,706,176 65,536
2001:db8::/49 2001:db8:: 2001:db8:0000:7fff:ffff:ffff:ffff:ffff 604,462,909,807,314,587,353,088 32,768
2001:db8::/50 2001:db8:: 2001:db8:0000:3fff:ffff:ffff:ffff:ffff 302,231,454,903,657,293,676,544 16,384
2001:db8::/51 2001:db8:: 2001:db8:0000:1fff:ffff:ffff:ffff:ffff 151,115,727,451,828,646,838,272 8,192
2001:db8::/52 2001:db8:: 2001:db8:0000:0fff:ffff:ffff:ffff:ffff 75,557,863,725,914,323,419,136 4,096
2001:db8::/53 2001:db8:: 2001:db8:0000:07ff:ffff:ffff:ffff:ffff 37,778,931,862,957,161,709,568 2,048
2001:db8::/54 2001:db8:: 2001:db8:0000:03ff:ffff:ffff:ffff:ffff 18,889,465,931,478,580,854,784 1,024
2001:db8::/55 2001:db8:: 2001:db8:0000:01ff:ffff:ffff:ffff:ffff 9,444,732,965,739,290,427,392 512
2001:db8::/56 2001:db8:: 2001:db8:0000:00ff:ffff:ffff:ffff:ffff 4,722,366,482,869,645,213,696 256
2001:db8::/57 2001:db8:: 2001:db8:0000:007f:ffff:ffff:ffff:ffff 2,361,183,241,434,822,606,848 128
2001:db8::/58 2001:db8:: 2001:db8:0000:003f:ffff:ffff:ffff:ffff 1,180,591,620,717,411,303,424 64
2001:db8::/59 2001:db8:: 2001:db8:0000:001f:ffff:ffff:ffff:ffff 590,295,810,358,705,651,712 32
2001:db8::/60 2001:db8:: 2001:db8:0000:000f:ffff:ffff:ffff:ffff 295,147,905,179,352,825,856 16
2001:db8::/61 2001:db8:: 2001:db8:0000:0007:ffff:ffff:ffff:ffff 147,573,952,589,676,412,928 8
2001:db8::/62 2001:db8:: 2001:db8:0000:0003:ffff:ffff:ffff:ffff 73,786,976,294,838,206,464 4
2001:db8::/63 2001:db8:: 2001:db8:0000:0001:ffff:ffff:ffff:ffff 36,893,488,147,419,103,232 2
2001:db8::/64 2001:db8:: 2001:db8:0000:0000:ffff:ffff:ffff:ffff 18,446,744,073,709,551,616 1
2001:db8::/65 2001:db8:: 2001:db8:0000:0000:7fff:ffff:ffff:ffff 9,223,372,036,854,775,808 -
2001:db8::/66 2001:db8:: 2001:db8:0000:0000:3fff:ffff:ffff:ffff 4,611,686,018,427,387,904
2001:db8::/67 2001:db8:: 2001:db8:0000:0000:1fff:ffff:ffff:ffff 2,305,843,009,213,693,952
2001:db8::/68 2001:db8:: 2001:db8:0000:0000:0fff:ffff:ffff:ffff 1,152,921,504,606,846,976
2001:db8::/69 2001:db8:: 2001:db8:0000:0000:07ff:ffff:ffff:ffff 576,460,752,303,423,488
2001:db8::/70 2001:db8:: 2001:db8:0000:0000:03ff:ffff:ffff:ffff 288,230,376,151,711,744
2001:db8::/71 2001:db8:: 2001:db8:0000:0000:01ff:ffff:ffff:ffff 144,115,188,075,855,872
2001:db8::/72 2001:db8:: 2001:db8:0000:0000:00ff:ffff:ffff:ffff 72,057,594,037,927,936
2001:db8::/73 2001:db8:: 2001:db8:0000:0000:007f:ffff:ffff:ffff 36,028,797,018,963,968
2001:db8::/74 2001:db8:: 2001:db8:0000:0000:003f:ffff:ffff:ffff 18,014,398,509,481,984
2001:db8::/75 2001:db8:: 2001:db8:0000:0000:001f:ffff:ffff:ffff 9,007,199,254,740,992
2001:db8::/76 2001:db8:: 2001:db8:0000:0000:000f:ffff:ffff:ffff 4,503,599,627,370,496
2001:db8::/77 2001:db8:: 2001:db8:0000:0000:0007:ffff:ffff:ffff 2,251,799,813,685,248
2001:db8::/78 2001:db8:: 2001:db8:0000:0000:0003:ffff:ffff:ffff 1,125,899,906,842,624
2001:db8::/79 2001:db8:: 2001:db8:0000:0000:0001:ffff:ffff:ffff 562,949,953,421,312
2001:db8::/80 2001:db8:: 2001:db8:0000:0000:0000:ffff:ffff:ffff 281,474,976,710,656
2001:db8::/81 2001:db8:: 2001:db8:0000:0000:0000:7fff:ffff:ffff 140,737,488,355,328
2001:db8::/82 2001:db8:: 2001:db8:0000:0000:0000:3fff:ffff:ffff 70,368,744,177,664
2001:db8::/83 2001:db8:: 2001:db8:0000:0000:0000:1fff:ffff:ffff 35,184,372,088,832
2001:db8::/84 2001:db8:: 2001:db8:0000:0000:0000:0fff:ffff:ffff 17,592,186,044,416
2001:db8::/85 2001:db8:: 2001:db8:0000:0000:0000:07ff:ffff:ffff 8,796,093,022,208
2001:db8::/86 2001:db8:: 2001:db8:0000:0000:0000:03ff:ffff:ffff 4,398,046,511,104
2001:db8::/87 2001:db8:: 2001:db8:0000:0000:0000:01ff:ffff:ffff 2,199,023,255,552
2001:db8::/88 2001:db8:: 2001:db8:0000:0000:0000:00ff:ffff:ffff 1,099,511,627,776
2001:db8::/89 2001:db8:: 2001:db8:0000:0000:0000:007f:ffff:ffff 549,755,813,888
2001:db8::/90 2001:db8:: 2001:db8:0000:0000:0000:003f:ffff:ffff 274,877,906,944
2001:db8::/91 2001:db8:: 2001:db8:0000:0000:0000:001f:ffff:ffff 137,438,953,472
2001:db8::/92 2001:db8:: 2001:db8:0000:0000:0000:000f:ffff:ffff 68,719,476,736
2001:db8::/93 2001:db8:: 2001:db8:0000:0000:0000:0007:ffff:ffff 34,359,738,368
2001:db8::/94 2001:db8:: 2001:db8:0000:0000:0000:0003:ffff:ffff 17,179,869,184
2001:db8::/95 2001:db8:: 2001:db8:0000:0000:0000:0001:ffff:ffff 8,589,934,592
2001:db8::/96 2001:db8:: 2001:db8:0000:0000:0000:0000:ffff:ffff 4,294,967,296
2001:db8::/97 2001:db8:: 2001:db8:0000:0000:0000:0000:7fff:ffff 2,147,483,648
2001:db8::/98 2001:db8:: 2001:db8:0000:0000:0000:0000:3fff:ffff 1,073,741,824
2001:db8::/99 2001:db8:: 2001:db8:0000:0000:0000:0000:1fff:ffff 536,870,912
2001:db8::/100 2001:db8:: 2001:db8:0000:0000:0000:0000:0fff:ffff 268,435,456
2001:db8::/101 2001:db8:: 2001:db8:0000:0000:0000:0000:07ff:ffff 134,217,728
2001:db8::/102 2001:db8:: 2001:db8:0000:0000:0000:0000:03ff:ffff 67,108,864
2001:db8::/103 2001:db8:: 2001:db8:0000:0000:0000:0000:01ff:ffff 33,554,432
2001:db8::/104 2001:db8:: 2001:db8:0000:0000:0000:0000:00ff:ffff 16,777,216
2001:db8::/105 2001:db8:: 2001:db8:0000:0000:0000:0000:007f:ffff 8,388,608
2001:db8::/106 2001:db8:: 2001:db8:0000:0000:0000:0000:003f:ffff 4,194,304
2001:db8::/107 2001:db8:: 2001:db8:0000:0000:0000:0000:001f:ffff 2,097,152
2001:db8::/108 2001:db8:: 2001:db8:0000:0000:0000:0000:000f:ffff 1,048,576
2001:db8::/109 2001:db8:: 2001:db8:0000:0000:0000:0000:0007:ffff 524,288
2001:db8::/110 2001:db8:: 2001:db8:0000:0000:0000:0000:0003:ffff 262,144
2001:db8::/111 2001:db8:: 2001:db8:0000:0000:0000:0000:0001:ffff 131,072
2001:db8::/112 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:ffff 65,536
2001:db8::/113 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:7fff 32,768
2001:db8::/114 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:3fff 16,384
2001:db8::/115 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:1fff 8,192
2001:db8::/116 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:0fff 4,096
2001:db8::/117 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:07ff 2,048
2001:db8::/118 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:03ff 1,024
2001:db8::/119 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:01ff 512
2001:db8::/120 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:00ff 256
2001:db8::/121 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:007f 128
2001:db8::/122 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:003f 64
2001:db8::/123 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:001f 32
2001:db8::/124 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:000f 16
2001:db8::/125 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:0007 8
2001:db8::/126 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:0003 4
2001:db8::/127 2001:db8:: 2001:db8:0000:0000:0000:0000:0000:0001 2
2001:db8::/128 2001:db8:: 2001:db8:: 1 -