Speed and call quality testMy IP addressIP subnet calculatorDNS reportWhoIs lookupRemote support

Internet and network

Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

Computers and devices

Update checkIs this computer, phone and browser up to date? With links to update.Camera and mic testCheck your webcam and microphone before a call.Test print pagePrint an A4 page to check a printer: edges, text, line art and colours.

Make and print

Clean textStrip hidden characters, smart quotes and odd spaces from pasted text.QR code makerMake a QR code for a link, contact or message. Nothing leaves your browser.Wi-Fi QR posterPrint an A4 poster that lets guests join your Wi-Fi by scanning.

Surftec support

Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

Surftec websiteServices, news and how to contact Surftec
Cloud Tools
Guest
GuestNot signed in

Surftec customers will be recognised automatically when they use these tools from their office network.

Customer sign-in is coming soon.

IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Prefix/120
Addresses256
/64 networksPart of one
Network
2c19:dd:ec00:c25:c25e:dd:dd79:de00/120
First address
2c19:dd:ec00:c25:c25e:dd:dd79:de00
Last address
2c19:dd:ec00:c25:c25e:dd:dd79:deff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:ec00:0c25:c25e:00dd:dd79:de00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
e.d.9.7.d.d.d.d.0.0.e.5.2.c.5.2.c.0.0.0.c.e.d.d.0.0.9.1.c.2.ip6.arpa
Split into smaller subnets/128
/121 (2)/122 (4)/123 (8)/124 (16)/127 (128)/128 (256)

2c19:dd:ec00:c25:c25e:dd:dd79:de00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:ec00:c25:c25e:dd:dd79:de00/1282c19:dd:ec00:c25:c25e:dd:dd79:de00
22c19:dd:ec00:c25:c25e:dd:dd79:de01/1282c19:dd:ec00:c25:c25e:dd:dd79:de01
32c19:dd:ec00:c25:c25e:dd:dd79:de02/1282c19:dd:ec00:c25:c25e:dd:dd79:de02
42c19:dd:ec00:c25:c25e:dd:dd79:de03/1282c19:dd:ec00:c25:c25e:dd:dd79:de03
52c19:dd:ec00:c25:c25e:dd:dd79:de04/1282c19:dd:ec00:c25:c25e:dd:dd79:de04
62c19:dd:ec00:c25:c25e:dd:dd79:de05/1282c19:dd:ec00:c25:c25e:dd:dd79:de05
72c19:dd:ec00:c25:c25e:dd:dd79:de06/1282c19:dd:ec00:c25:c25e:dd:dd79:de06
82c19:dd:ec00:c25:c25e:dd:dd79:de07/1282c19:dd:ec00:c25:c25e:dd:dd79:de07
92c19:dd:ec00:c25:c25e:dd:dd79:de08/1282c19:dd:ec00:c25:c25e:dd:dd79:de08
102c19:dd:ec00:c25:c25e:dd:dd79:de09/1282c19:dd:ec00:c25:c25e:dd:dd79:de09
112c19:dd:ec00:c25:c25e:dd:dd79:de0a/1282c19:dd:ec00:c25:c25e:dd:dd79:de0a
122c19:dd:ec00:c25:c25e:dd:dd79:de0b/1282c19:dd:ec00:c25:c25e:dd:dd79:de0b
132c19:dd:ec00:c25:c25e:dd:dd79:de0c/1282c19:dd:ec00:c25:c25e:dd:dd79:de0c
142c19:dd:ec00:c25:c25e:dd:dd79:de0d/1282c19:dd:ec00:c25:c25e:dd:dd79:de0d
152c19:dd:ec00:c25:c25e:dd:dd79:de0e/1282c19:dd:ec00:c25:c25e:dd:dd79:de0e
162c19:dd:ec00:c25:c25e:dd:dd79:de0f/1282c19:dd:ec00:c25:c25e:dd:dd79:de0f
172c19:dd:ec00:c25:c25e:dd:dd79:de10/1282c19:dd:ec00:c25:c25e:dd:dd79:de10
182c19:dd:ec00:c25:c25e:dd:dd79:de11/1282c19:dd:ec00:c25:c25e:dd:dd79:de11
192c19:dd:ec00:c25:c25e:dd:dd79:de12/1282c19:dd:ec00:c25:c25e:dd:dd79:de12
202c19:dd:ec00:c25:c25e:dd:dd79:de13/1282c19:dd:ec00:c25:c25e:dd:dd79:de13
212c19:dd:ec00:c25:c25e:dd:dd79:de14/1282c19:dd:ec00:c25:c25e:dd:dd79:de14
222c19:dd:ec00:c25:c25e:dd:dd79:de15/1282c19:dd:ec00:c25:c25e:dd:dd79:de15
232c19:dd:ec00:c25:c25e:dd:dd79:de16/1282c19:dd:ec00:c25:c25e:dd:dd79:de16
242c19:dd:ec00:c25:c25e:dd:dd79:de17/1282c19:dd:ec00:c25:c25e:dd:dd79:de17
252c19:dd:ec00:c25:c25e:dd:dd79:de18/1282c19:dd:ec00:c25:c25e:dd:dd79:de18
262c19:dd:ec00:c25:c25e:dd:dd79:de19/1282c19:dd:ec00:c25:c25e:dd:dd79:de19
272c19:dd:ec00:c25:c25e:dd:dd79:de1a/1282c19:dd:ec00:c25:c25e:dd:dd79:de1a
282c19:dd:ec00:c25:c25e:dd:dd79:de1b/1282c19:dd:ec00:c25:c25e:dd:dd79:de1b
292c19:dd:ec00:c25:c25e:dd:dd79:de1c/1282c19:dd:ec00:c25:c25e:dd:dd79:de1c
302c19:dd:ec00:c25:c25e:dd:dd79:de1d/1282c19:dd:ec00:c25:c25e:dd:dd79:de1d
312c19:dd:ec00:c25:c25e:dd:dd79:de1e/1282c19:dd:ec00:c25:c25e:dd:dd79:de1e
322c19:dd:ec00:c25:c25e:dd:dd79:de1f/1282c19:dd:ec00:c25:c25e:dd:dd79:de1f
332c19:dd:ec00:c25:c25e:dd:dd79:de20/1282c19:dd:ec00:c25:c25e:dd:dd79:de20
342c19:dd:ec00:c25:c25e:dd:dd79:de21/1282c19:dd:ec00:c25:c25e:dd:dd79:de21
352c19:dd:ec00:c25:c25e:dd:dd79:de22/1282c19:dd:ec00:c25:c25e:dd:dd79:de22
362c19:dd:ec00:c25:c25e:dd:dd79:de23/1282c19:dd:ec00:c25:c25e:dd:dd79:de23
372c19:dd:ec00:c25:c25e:dd:dd79:de24/1282c19:dd:ec00:c25:c25e:dd:dd79:de24
382c19:dd:ec00:c25:c25e:dd:dd79:de25/1282c19:dd:ec00:c25:c25e:dd:dd79:de25
392c19:dd:ec00:c25:c25e:dd:dd79:de26/1282c19:dd:ec00:c25:c25e:dd:dd79:de26
402c19:dd:ec00:c25:c25e:dd:dd79:de27/1282c19:dd:ec00:c25:c25e:dd:dd79:de27
412c19:dd:ec00:c25:c25e:dd:dd79:de28/1282c19:dd:ec00:c25:c25e:dd:dd79:de28
422c19:dd:ec00:c25:c25e:dd:dd79:de29/1282c19:dd:ec00:c25:c25e:dd:dd79:de29
432c19:dd:ec00:c25:c25e:dd:dd79:de2a/1282c19:dd:ec00:c25:c25e:dd:dd79:de2a
442c19:dd:ec00:c25:c25e:dd:dd79:de2b/1282c19:dd:ec00:c25:c25e:dd:dd79:de2b
452c19:dd:ec00:c25:c25e:dd:dd79:de2c/1282c19:dd:ec00:c25:c25e:dd:dd79:de2c
462c19:dd:ec00:c25:c25e:dd:dd79:de2d/1282c19:dd:ec00:c25:c25e:dd:dd79:de2d
472c19:dd:ec00:c25:c25e:dd:dd79:de2e/1282c19:dd:ec00:c25:c25e:dd:dd79:de2e
482c19:dd:ec00:c25:c25e:dd:dd79:de2f/1282c19:dd:ec00:c25:c25e:dd:dd79:de2f
492c19:dd:ec00:c25:c25e:dd:dd79:de30/1282c19:dd:ec00:c25:c25e:dd:dd79:de30
502c19:dd:ec00:c25:c25e:dd:dd79:de31/1282c19:dd:ec00:c25:c25e:dd:dd79:de31
512c19:dd:ec00:c25:c25e:dd:dd79:de32/1282c19:dd:ec00:c25:c25e:dd:dd79:de32
522c19:dd:ec00:c25:c25e:dd:dd79:de33/1282c19:dd:ec00:c25:c25e:dd:dd79:de33
532c19:dd:ec00:c25:c25e:dd:dd79:de34/1282c19:dd:ec00:c25:c25e:dd:dd79:de34
542c19:dd:ec00:c25:c25e:dd:dd79:de35/1282c19:dd:ec00:c25:c25e:dd:dd79:de35
552c19:dd:ec00:c25:c25e:dd:dd79:de36/1282c19:dd:ec00:c25:c25e:dd:dd79:de36
562c19:dd:ec00:c25:c25e:dd:dd79:de37/1282c19:dd:ec00:c25:c25e:dd:dd79:de37
572c19:dd:ec00:c25:c25e:dd:dd79:de38/1282c19:dd:ec00:c25:c25e:dd:dd79:de38
582c19:dd:ec00:c25:c25e:dd:dd79:de39/1282c19:dd:ec00:c25:c25e:dd:dd79:de39
592c19:dd:ec00:c25:c25e:dd:dd79:de3a/1282c19:dd:ec00:c25:c25e:dd:dd79:de3a
602c19:dd:ec00:c25:c25e:dd:dd79:de3b/1282c19:dd:ec00:c25:c25e:dd:dd79:de3b
612c19:dd:ec00:c25:c25e:dd:dd79:de3c/1282c19:dd:ec00:c25:c25e:dd:dd79:de3c
622c19:dd:ec00:c25:c25e:dd:dd79:de3d/1282c19:dd:ec00:c25:c25e:dd:dd79:de3d
632c19:dd:ec00:c25:c25e:dd:dd79:de3e/1282c19:dd:ec00:c25:c25e:dd:dd79:de3e
642c19:dd:ec00:c25:c25e:dd:dd79:de3f/1282c19:dd:ec00:c25:c25e:dd:dd79:de3f
652c19:dd:ec00:c25:c25e:dd:dd79:de40/1282c19:dd:ec00:c25:c25e:dd:dd79:de40
662c19:dd:ec00:c25:c25e:dd:dd79:de41/1282c19:dd:ec00:c25:c25e:dd:dd79:de41
672c19:dd:ec00:c25:c25e:dd:dd79:de42/1282c19:dd:ec00:c25:c25e:dd:dd79:de42
682c19:dd:ec00:c25:c25e:dd:dd79:de43/1282c19:dd:ec00:c25:c25e:dd:dd79:de43
692c19:dd:ec00:c25:c25e:dd:dd79:de44/1282c19:dd:ec00:c25:c25e:dd:dd79:de44
702c19:dd:ec00:c25:c25e:dd:dd79:de45/1282c19:dd:ec00:c25:c25e:dd:dd79:de45
712c19:dd:ec00:c25:c25e:dd:dd79:de46/1282c19:dd:ec00:c25:c25e:dd:dd79:de46
722c19:dd:ec00:c25:c25e:dd:dd79:de47/1282c19:dd:ec00:c25:c25e:dd:dd79:de47
732c19:dd:ec00:c25:c25e:dd:dd79:de48/1282c19:dd:ec00:c25:c25e:dd:dd79:de48
742c19:dd:ec00:c25:c25e:dd:dd79:de49/1282c19:dd:ec00:c25:c25e:dd:dd79:de49
752c19:dd:ec00:c25:c25e:dd:dd79:de4a/1282c19:dd:ec00:c25:c25e:dd:dd79:de4a
762c19:dd:ec00:c25:c25e:dd:dd79:de4b/1282c19:dd:ec00:c25:c25e:dd:dd79:de4b
772c19:dd:ec00:c25:c25e:dd:dd79:de4c/1282c19:dd:ec00:c25:c25e:dd:dd79:de4c
782c19:dd:ec00:c25:c25e:dd:dd79:de4d/1282c19:dd:ec00:c25:c25e:dd:dd79:de4d
792c19:dd:ec00:c25:c25e:dd:dd79:de4e/1282c19:dd:ec00:c25:c25e:dd:dd79:de4e
802c19:dd:ec00:c25:c25e:dd:dd79:de4f/1282c19:dd:ec00:c25:c25e:dd:dd79:de4f
812c19:dd:ec00:c25:c25e:dd:dd79:de50/1282c19:dd:ec00:c25:c25e:dd:dd79:de50
822c19:dd:ec00:c25:c25e:dd:dd79:de51/1282c19:dd:ec00:c25:c25e:dd:dd79:de51
832c19:dd:ec00:c25:c25e:dd:dd79:de52/1282c19:dd:ec00:c25:c25e:dd:dd79:de52
842c19:dd:ec00:c25:c25e:dd:dd79:de53/1282c19:dd:ec00:c25:c25e:dd:dd79:de53
852c19:dd:ec00:c25:c25e:dd:dd79:de54/1282c19:dd:ec00:c25:c25e:dd:dd79:de54
862c19:dd:ec00:c25:c25e:dd:dd79:de55/1282c19:dd:ec00:c25:c25e:dd:dd79:de55
872c19:dd:ec00:c25:c25e:dd:dd79:de56/1282c19:dd:ec00:c25:c25e:dd:dd79:de56
882c19:dd:ec00:c25:c25e:dd:dd79:de57/1282c19:dd:ec00:c25:c25e:dd:dd79:de57
892c19:dd:ec00:c25:c25e:dd:dd79:de58/1282c19:dd:ec00:c25:c25e:dd:dd79:de58
902c19:dd:ec00:c25:c25e:dd:dd79:de59/1282c19:dd:ec00:c25:c25e:dd:dd79:de59
912c19:dd:ec00:c25:c25e:dd:dd79:de5a/1282c19:dd:ec00:c25:c25e:dd:dd79:de5a
922c19:dd:ec00:c25:c25e:dd:dd79:de5b/1282c19:dd:ec00:c25:c25e:dd:dd79:de5b
932c19:dd:ec00:c25:c25e:dd:dd79:de5c/1282c19:dd:ec00:c25:c25e:dd:dd79:de5c
942c19:dd:ec00:c25:c25e:dd:dd79:de5d/1282c19:dd:ec00:c25:c25e:dd:dd79:de5d
952c19:dd:ec00:c25:c25e:dd:dd79:de5e/1282c19:dd:ec00:c25:c25e:dd:dd79:de5e
962c19:dd:ec00:c25:c25e:dd:dd79:de5f/1282c19:dd:ec00:c25:c25e:dd:dd79:de5f
972c19:dd:ec00:c25:c25e:dd:dd79:de60/1282c19:dd:ec00:c25:c25e:dd:dd79:de60
982c19:dd:ec00:c25:c25e:dd:dd79:de61/1282c19:dd:ec00:c25:c25e:dd:dd79:de61
992c19:dd:ec00:c25:c25e:dd:dd79:de62/1282c19:dd:ec00:c25:c25e:dd:dd79:de62
1002c19:dd:ec00:c25:c25e:dd:dd79:de63/1282c19:dd:ec00:c25:c25e:dd:dd79:de63
1012c19:dd:ec00:c25:c25e:dd:dd79:de64/1282c19:dd:ec00:c25:c25e:dd:dd79:de64
1022c19:dd:ec00:c25:c25e:dd:dd79:de65/1282c19:dd:ec00:c25:c25e:dd:dd79:de65
1032c19:dd:ec00:c25:c25e:dd:dd79:de66/1282c19:dd:ec00:c25:c25e:dd:dd79:de66
1042c19:dd:ec00:c25:c25e:dd:dd79:de67/1282c19:dd:ec00:c25:c25e:dd:dd79:de67
1052c19:dd:ec00:c25:c25e:dd:dd79:de68/1282c19:dd:ec00:c25:c25e:dd:dd79:de68
1062c19:dd:ec00:c25:c25e:dd:dd79:de69/1282c19:dd:ec00:c25:c25e:dd:dd79:de69
1072c19:dd:ec00:c25:c25e:dd:dd79:de6a/1282c19:dd:ec00:c25:c25e:dd:dd79:de6a
1082c19:dd:ec00:c25:c25e:dd:dd79:de6b/1282c19:dd:ec00:c25:c25e:dd:dd79:de6b
1092c19:dd:ec00:c25:c25e:dd:dd79:de6c/1282c19:dd:ec00:c25:c25e:dd:dd79:de6c
1102c19:dd:ec00:c25:c25e:dd:dd79:de6d/1282c19:dd:ec00:c25:c25e:dd:dd79:de6d
1112c19:dd:ec00:c25:c25e:dd:dd79:de6e/1282c19:dd:ec00:c25:c25e:dd:dd79:de6e
1122c19:dd:ec00:c25:c25e:dd:dd79:de6f/1282c19:dd:ec00:c25:c25e:dd:dd79:de6f
1132c19:dd:ec00:c25:c25e:dd:dd79:de70/1282c19:dd:ec00:c25:c25e:dd:dd79:de70
1142c19:dd:ec00:c25:c25e:dd:dd79:de71/1282c19:dd:ec00:c25:c25e:dd:dd79:de71
1152c19:dd:ec00:c25:c25e:dd:dd79:de72/1282c19:dd:ec00:c25:c25e:dd:dd79:de72
1162c19:dd:ec00:c25:c25e:dd:dd79:de73/1282c19:dd:ec00:c25:c25e:dd:dd79:de73
1172c19:dd:ec00:c25:c25e:dd:dd79:de74/1282c19:dd:ec00:c25:c25e:dd:dd79:de74
1182c19:dd:ec00:c25:c25e:dd:dd79:de75/1282c19:dd:ec00:c25:c25e:dd:dd79:de75
1192c19:dd:ec00:c25:c25e:dd:dd79:de76/1282c19:dd:ec00:c25:c25e:dd:dd79:de76
1202c19:dd:ec00:c25:c25e:dd:dd79:de77/1282c19:dd:ec00:c25:c25e:dd:dd79:de77
1212c19:dd:ec00:c25:c25e:dd:dd79:de78/1282c19:dd:ec00:c25:c25e:dd:dd79:de78
1222c19:dd:ec00:c25:c25e:dd:dd79:de79/1282c19:dd:ec00:c25:c25e:dd:dd79:de79
1232c19:dd:ec00:c25:c25e:dd:dd79:de7a/1282c19:dd:ec00:c25:c25e:dd:dd79:de7a
1242c19:dd:ec00:c25:c25e:dd:dd79:de7b/1282c19:dd:ec00:c25:c25e:dd:dd79:de7b
1252c19:dd:ec00:c25:c25e:dd:dd79:de7c/1282c19:dd:ec00:c25:c25e:dd:dd79:de7c
1262c19:dd:ec00:c25:c25e:dd:dd79:de7d/1282c19:dd:ec00:c25:c25e:dd:dd79:de7d
1272c19:dd:ec00:c25:c25e:dd:dd79:de7e/1282c19:dd:ec00:c25:c25e:dd:dd79:de7e
1282c19:dd:ec00:c25:c25e:dd:dd79:de7f/1282c19:dd:ec00:c25:c25e:dd:dd79:de7f
1292c19:dd:ec00:c25:c25e:dd:dd79:de80/1282c19:dd:ec00:c25:c25e:dd:dd79:de80
1302c19:dd:ec00:c25:c25e:dd:dd79:de81/1282c19:dd:ec00:c25:c25e:dd:dd79:de81
1312c19:dd:ec00:c25:c25e:dd:dd79:de82/1282c19:dd:ec00:c25:c25e:dd:dd79:de82
1322c19:dd:ec00:c25:c25e:dd:dd79:de83/1282c19:dd:ec00:c25:c25e:dd:dd79:de83
1332c19:dd:ec00:c25:c25e:dd:dd79:de84/1282c19:dd:ec00:c25:c25e:dd:dd79:de84
1342c19:dd:ec00:c25:c25e:dd:dd79:de85/1282c19:dd:ec00:c25:c25e:dd:dd79:de85
1352c19:dd:ec00:c25:c25e:dd:dd79:de86/1282c19:dd:ec00:c25:c25e:dd:dd79:de86
1362c19:dd:ec00:c25:c25e:dd:dd79:de87/1282c19:dd:ec00:c25:c25e:dd:dd79:de87
1372c19:dd:ec00:c25:c25e:dd:dd79:de88/1282c19:dd:ec00:c25:c25e:dd:dd79:de88
1382c19:dd:ec00:c25:c25e:dd:dd79:de89/1282c19:dd:ec00:c25:c25e:dd:dd79:de89
1392c19:dd:ec00:c25:c25e:dd:dd79:de8a/1282c19:dd:ec00:c25:c25e:dd:dd79:de8a
1402c19:dd:ec00:c25:c25e:dd:dd79:de8b/1282c19:dd:ec00:c25:c25e:dd:dd79:de8b
1412c19:dd:ec00:c25:c25e:dd:dd79:de8c/1282c19:dd:ec00:c25:c25e:dd:dd79:de8c
1422c19:dd:ec00:c25:c25e:dd:dd79:de8d/1282c19:dd:ec00:c25:c25e:dd:dd79:de8d
1432c19:dd:ec00:c25:c25e:dd:dd79:de8e/1282c19:dd:ec00:c25:c25e:dd:dd79:de8e
1442c19:dd:ec00:c25:c25e:dd:dd79:de8f/1282c19:dd:ec00:c25:c25e:dd:dd79:de8f
1452c19:dd:ec00:c25:c25e:dd:dd79:de90/1282c19:dd:ec00:c25:c25e:dd:dd79:de90
1462c19:dd:ec00:c25:c25e:dd:dd79:de91/1282c19:dd:ec00:c25:c25e:dd:dd79:de91
1472c19:dd:ec00:c25:c25e:dd:dd79:de92/1282c19:dd:ec00:c25:c25e:dd:dd79:de92
1482c19:dd:ec00:c25:c25e:dd:dd79:de93/1282c19:dd:ec00:c25:c25e:dd:dd79:de93
1492c19:dd:ec00:c25:c25e:dd:dd79:de94/1282c19:dd:ec00:c25:c25e:dd:dd79:de94
1502c19:dd:ec00:c25:c25e:dd:dd79:de95/1282c19:dd:ec00:c25:c25e:dd:dd79:de95
1512c19:dd:ec00:c25:c25e:dd:dd79:de96/1282c19:dd:ec00:c25:c25e:dd:dd79:de96
1522c19:dd:ec00:c25:c25e:dd:dd79:de97/1282c19:dd:ec00:c25:c25e:dd:dd79:de97
1532c19:dd:ec00:c25:c25e:dd:dd79:de98/1282c19:dd:ec00:c25:c25e:dd:dd79:de98
1542c19:dd:ec00:c25:c25e:dd:dd79:de99/1282c19:dd:ec00:c25:c25e:dd:dd79:de99
1552c19:dd:ec00:c25:c25e:dd:dd79:de9a/1282c19:dd:ec00:c25:c25e:dd:dd79:de9a
1562c19:dd:ec00:c25:c25e:dd:dd79:de9b/1282c19:dd:ec00:c25:c25e:dd:dd79:de9b
1572c19:dd:ec00:c25:c25e:dd:dd79:de9c/1282c19:dd:ec00:c25:c25e:dd:dd79:de9c
1582c19:dd:ec00:c25:c25e:dd:dd79:de9d/1282c19:dd:ec00:c25:c25e:dd:dd79:de9d
1592c19:dd:ec00:c25:c25e:dd:dd79:de9e/1282c19:dd:ec00:c25:c25e:dd:dd79:de9e
1602c19:dd:ec00:c25:c25e:dd:dd79:de9f/1282c19:dd:ec00:c25:c25e:dd:dd79:de9f
1612c19:dd:ec00:c25:c25e:dd:dd79:dea0/1282c19:dd:ec00:c25:c25e:dd:dd79:dea0
1622c19:dd:ec00:c25:c25e:dd:dd79:dea1/1282c19:dd:ec00:c25:c25e:dd:dd79:dea1
1632c19:dd:ec00:c25:c25e:dd:dd79:dea2/1282c19:dd:ec00:c25:c25e:dd:dd79:dea2
1642c19:dd:ec00:c25:c25e:dd:dd79:dea3/1282c19:dd:ec00:c25:c25e:dd:dd79:dea3
1652c19:dd:ec00:c25:c25e:dd:dd79:dea4/1282c19:dd:ec00:c25:c25e:dd:dd79:dea4
1662c19:dd:ec00:c25:c25e:dd:dd79:dea5/1282c19:dd:ec00:c25:c25e:dd:dd79:dea5
1672c19:dd:ec00:c25:c25e:dd:dd79:dea6/1282c19:dd:ec00:c25:c25e:dd:dd79:dea6
1682c19:dd:ec00:c25:c25e:dd:dd79:dea7/1282c19:dd:ec00:c25:c25e:dd:dd79:dea7
1692c19:dd:ec00:c25:c25e:dd:dd79:dea8/1282c19:dd:ec00:c25:c25e:dd:dd79:dea8
1702c19:dd:ec00:c25:c25e:dd:dd79:dea9/1282c19:dd:ec00:c25:c25e:dd:dd79:dea9
1712c19:dd:ec00:c25:c25e:dd:dd79:deaa/1282c19:dd:ec00:c25:c25e:dd:dd79:deaa
1722c19:dd:ec00:c25:c25e:dd:dd79:deab/1282c19:dd:ec00:c25:c25e:dd:dd79:deab
1732c19:dd:ec00:c25:c25e:dd:dd79:deac/1282c19:dd:ec00:c25:c25e:dd:dd79:deac
1742c19:dd:ec00:c25:c25e:dd:dd79:dead/1282c19:dd:ec00:c25:c25e:dd:dd79:dead
1752c19:dd:ec00:c25:c25e:dd:dd79:deae/1282c19:dd:ec00:c25:c25e:dd:dd79:deae
1762c19:dd:ec00:c25:c25e:dd:dd79:deaf/1282c19:dd:ec00:c25:c25e:dd:dd79:deaf
1772c19:dd:ec00:c25:c25e:dd:dd79:deb0/1282c19:dd:ec00:c25:c25e:dd:dd79:deb0
1782c19:dd:ec00:c25:c25e:dd:dd79:deb1/1282c19:dd:ec00:c25:c25e:dd:dd79:deb1
1792c19:dd:ec00:c25:c25e:dd:dd79:deb2/1282c19:dd:ec00:c25:c25e:dd:dd79:deb2
1802c19:dd:ec00:c25:c25e:dd:dd79:deb3/1282c19:dd:ec00:c25:c25e:dd:dd79:deb3
1812c19:dd:ec00:c25:c25e:dd:dd79:deb4/1282c19:dd:ec00:c25:c25e:dd:dd79:deb4
1822c19:dd:ec00:c25:c25e:dd:dd79:deb5/1282c19:dd:ec00:c25:c25e:dd:dd79:deb5
1832c19:dd:ec00:c25:c25e:dd:dd79:deb6/1282c19:dd:ec00:c25:c25e:dd:dd79:deb6
1842c19:dd:ec00:c25:c25e:dd:dd79:deb7/1282c19:dd:ec00:c25:c25e:dd:dd79:deb7
1852c19:dd:ec00:c25:c25e:dd:dd79:deb8/1282c19:dd:ec00:c25:c25e:dd:dd79:deb8
1862c19:dd:ec00:c25:c25e:dd:dd79:deb9/1282c19:dd:ec00:c25:c25e:dd:dd79:deb9
1872c19:dd:ec00:c25:c25e:dd:dd79:deba/1282c19:dd:ec00:c25:c25e:dd:dd79:deba
1882c19:dd:ec00:c25:c25e:dd:dd79:debb/1282c19:dd:ec00:c25:c25e:dd:dd79:debb
1892c19:dd:ec00:c25:c25e:dd:dd79:debc/1282c19:dd:ec00:c25:c25e:dd:dd79:debc
1902c19:dd:ec00:c25:c25e:dd:dd79:debd/1282c19:dd:ec00:c25:c25e:dd:dd79:debd
1912c19:dd:ec00:c25:c25e:dd:dd79:debe/1282c19:dd:ec00:c25:c25e:dd:dd79:debe
1922c19:dd:ec00:c25:c25e:dd:dd79:debf/1282c19:dd:ec00:c25:c25e:dd:dd79:debf
1932c19:dd:ec00:c25:c25e:dd:dd79:dec0/1282c19:dd:ec00:c25:c25e:dd:dd79:dec0
1942c19:dd:ec00:c25:c25e:dd:dd79:dec1/1282c19:dd:ec00:c25:c25e:dd:dd79:dec1
1952c19:dd:ec00:c25:c25e:dd:dd79:dec2/1282c19:dd:ec00:c25:c25e:dd:dd79:dec2
1962c19:dd:ec00:c25:c25e:dd:dd79:dec3/1282c19:dd:ec00:c25:c25e:dd:dd79:dec3
1972c19:dd:ec00:c25:c25e:dd:dd79:dec4/1282c19:dd:ec00:c25:c25e:dd:dd79:dec4
1982c19:dd:ec00:c25:c25e:dd:dd79:dec5/1282c19:dd:ec00:c25:c25e:dd:dd79:dec5
1992c19:dd:ec00:c25:c25e:dd:dd79:dec6/1282c19:dd:ec00:c25:c25e:dd:dd79:dec6
2002c19:dd:ec00:c25:c25e:dd:dd79:dec7/1282c19:dd:ec00:c25:c25e:dd:dd79:dec7
2012c19:dd:ec00:c25:c25e:dd:dd79:dec8/1282c19:dd:ec00:c25:c25e:dd:dd79:dec8
2022c19:dd:ec00:c25:c25e:dd:dd79:dec9/1282c19:dd:ec00:c25:c25e:dd:dd79:dec9
2032c19:dd:ec00:c25:c25e:dd:dd79:deca/1282c19:dd:ec00:c25:c25e:dd:dd79:deca
2042c19:dd:ec00:c25:c25e:dd:dd79:decb/1282c19:dd:ec00:c25:c25e:dd:dd79:decb
2052c19:dd:ec00:c25:c25e:dd:dd79:decc/1282c19:dd:ec00:c25:c25e:dd:dd79:decc
2062c19:dd:ec00:c25:c25e:dd:dd79:decd/1282c19:dd:ec00:c25:c25e:dd:dd79:decd
2072c19:dd:ec00:c25:c25e:dd:dd79:dece/1282c19:dd:ec00:c25:c25e:dd:dd79:dece
2082c19:dd:ec00:c25:c25e:dd:dd79:decf/1282c19:dd:ec00:c25:c25e:dd:dd79:decf
2092c19:dd:ec00:c25:c25e:dd:dd79:ded0/1282c19:dd:ec00:c25:c25e:dd:dd79:ded0
2102c19:dd:ec00:c25:c25e:dd:dd79:ded1/1282c19:dd:ec00:c25:c25e:dd:dd79:ded1
2112c19:dd:ec00:c25:c25e:dd:dd79:ded2/1282c19:dd:ec00:c25:c25e:dd:dd79:ded2
2122c19:dd:ec00:c25:c25e:dd:dd79:ded3/1282c19:dd:ec00:c25:c25e:dd:dd79:ded3
2132c19:dd:ec00:c25:c25e:dd:dd79:ded4/1282c19:dd:ec00:c25:c25e:dd:dd79:ded4
2142c19:dd:ec00:c25:c25e:dd:dd79:ded5/1282c19:dd:ec00:c25:c25e:dd:dd79:ded5
2152c19:dd:ec00:c25:c25e:dd:dd79:ded6/1282c19:dd:ec00:c25:c25e:dd:dd79:ded6
2162c19:dd:ec00:c25:c25e:dd:dd79:ded7/1282c19:dd:ec00:c25:c25e:dd:dd79:ded7
2172c19:dd:ec00:c25:c25e:dd:dd79:ded8/1282c19:dd:ec00:c25:c25e:dd:dd79:ded8
2182c19:dd:ec00:c25:c25e:dd:dd79:ded9/1282c19:dd:ec00:c25:c25e:dd:dd79:ded9
2192c19:dd:ec00:c25:c25e:dd:dd79:deda/1282c19:dd:ec00:c25:c25e:dd:dd79:deda
2202c19:dd:ec00:c25:c25e:dd:dd79:dedb/1282c19:dd:ec00:c25:c25e:dd:dd79:dedb
2212c19:dd:ec00:c25:c25e:dd:dd79:dedc/1282c19:dd:ec00:c25:c25e:dd:dd79:dedc
2222c19:dd:ec00:c25:c25e:dd:dd79:dedd/1282c19:dd:ec00:c25:c25e:dd:dd79:dedd
2232c19:dd:ec00:c25:c25e:dd:dd79:dede/1282c19:dd:ec00:c25:c25e:dd:dd79:dede
2242c19:dd:ec00:c25:c25e:dd:dd79:dedf/1282c19:dd:ec00:c25:c25e:dd:dd79:dedf
2252c19:dd:ec00:c25:c25e:dd:dd79:dee0/1282c19:dd:ec00:c25:c25e:dd:dd79:dee0
2262c19:dd:ec00:c25:c25e:dd:dd79:dee1/1282c19:dd:ec00:c25:c25e:dd:dd79:dee1
2272c19:dd:ec00:c25:c25e:dd:dd79:dee2/1282c19:dd:ec00:c25:c25e:dd:dd79:dee2
2282c19:dd:ec00:c25:c25e:dd:dd79:dee3/1282c19:dd:ec00:c25:c25e:dd:dd79:dee3
2292c19:dd:ec00:c25:c25e:dd:dd79:dee4/1282c19:dd:ec00:c25:c25e:dd:dd79:dee4
2302c19:dd:ec00:c25:c25e:dd:dd79:dee5/1282c19:dd:ec00:c25:c25e:dd:dd79:dee5
2312c19:dd:ec00:c25:c25e:dd:dd79:dee6/1282c19:dd:ec00:c25:c25e:dd:dd79:dee6
2322c19:dd:ec00:c25:c25e:dd:dd79:dee7/1282c19:dd:ec00:c25:c25e:dd:dd79:dee7
2332c19:dd:ec00:c25:c25e:dd:dd79:dee8/1282c19:dd:ec00:c25:c25e:dd:dd79:dee8
2342c19:dd:ec00:c25:c25e:dd:dd79:dee9/1282c19:dd:ec00:c25:c25e:dd:dd79:dee9
2352c19:dd:ec00:c25:c25e:dd:dd79:deea/1282c19:dd:ec00:c25:c25e:dd:dd79:deea
2362c19:dd:ec00:c25:c25e:dd:dd79:deeb/1282c19:dd:ec00:c25:c25e:dd:dd79:deeb
2372c19:dd:ec00:c25:c25e:dd:dd79:deec/1282c19:dd:ec00:c25:c25e:dd:dd79:deec
2382c19:dd:ec00:c25:c25e:dd:dd79:deed/1282c19:dd:ec00:c25:c25e:dd:dd79:deed
2392c19:dd:ec00:c25:c25e:dd:dd79:deee/1282c19:dd:ec00:c25:c25e:dd:dd79:deee
2402c19:dd:ec00:c25:c25e:dd:dd79:deef/1282c19:dd:ec00:c25:c25e:dd:dd79:deef
2412c19:dd:ec00:c25:c25e:dd:dd79:def0/1282c19:dd:ec00:c25:c25e:dd:dd79:def0
2422c19:dd:ec00:c25:c25e:dd:dd79:def1/1282c19:dd:ec00:c25:c25e:dd:dd79:def1
2432c19:dd:ec00:c25:c25e:dd:dd79:def2/1282c19:dd:ec00:c25:c25e:dd:dd79:def2
2442c19:dd:ec00:c25:c25e:dd:dd79:def3/1282c19:dd:ec00:c25:c25e:dd:dd79:def3
2452c19:dd:ec00:c25:c25e:dd:dd79:def4/1282c19:dd:ec00:c25:c25e:dd:dd79:def4
2462c19:dd:ec00:c25:c25e:dd:dd79:def5/1282c19:dd:ec00:c25:c25e:dd:dd79:def5
2472c19:dd:ec00:c25:c25e:dd:dd79:def6/1282c19:dd:ec00:c25:c25e:dd:dd79:def6
2482c19:dd:ec00:c25:c25e:dd:dd79:def7/1282c19:dd:ec00:c25:c25e:dd:dd79:def7
2492c19:dd:ec00:c25:c25e:dd:dd79:def8/1282c19:dd:ec00:c25:c25e:dd:dd79:def8
2502c19:dd:ec00:c25:c25e:dd:dd79:def9/1282c19:dd:ec00:c25:c25e:dd:dd79:def9
2512c19:dd:ec00:c25:c25e:dd:dd79:defa/1282c19:dd:ec00:c25:c25e:dd:dd79:defa
2522c19:dd:ec00:c25:c25e:dd:dd79:defb/1282c19:dd:ec00:c25:c25e:dd:dd79:defb
2532c19:dd:ec00:c25:c25e:dd:dd79:defc/1282c19:dd:ec00:c25:c25e:dd:dd79:defc
2542c19:dd:ec00:c25:c25e:dd:dd79:defd/1282c19:dd:ec00:c25:c25e:dd:dd79:defd
2552c19:dd:ec00:c25:c25e:dd:dd79:defe/1282c19:dd:ec00:c25:c25e:dd:dd79:defe
2562c19:dd:ec00:c25:c25e:dd:dd79:deff/1282c19:dd:ec00:c25:c25e:dd:dd79:deff

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.