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:d9:dd:c25:c25:94de:4d00/120
First address
2c19:dd:d9:dd:c25:c25:94de:4d00
Last address
2c19:dd:d9:dd:c25:c25:94de:4dff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:94de:4d00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
d.4.e.d.4.9.5.2.c.0.5.2.c.0.d.d.0.0.9.d.0.0.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:d9:dd:c25:c25:94de:4d00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:94de:4d00/1282c19:dd:d9:dd:c25:c25:94de:4d00
22c19:dd:d9:dd:c25:c25:94de:4d01/1282c19:dd:d9:dd:c25:c25:94de:4d01
32c19:dd:d9:dd:c25:c25:94de:4d02/1282c19:dd:d9:dd:c25:c25:94de:4d02
42c19:dd:d9:dd:c25:c25:94de:4d03/1282c19:dd:d9:dd:c25:c25:94de:4d03
52c19:dd:d9:dd:c25:c25:94de:4d04/1282c19:dd:d9:dd:c25:c25:94de:4d04
62c19:dd:d9:dd:c25:c25:94de:4d05/1282c19:dd:d9:dd:c25:c25:94de:4d05
72c19:dd:d9:dd:c25:c25:94de:4d06/1282c19:dd:d9:dd:c25:c25:94de:4d06
82c19:dd:d9:dd:c25:c25:94de:4d07/1282c19:dd:d9:dd:c25:c25:94de:4d07
92c19:dd:d9:dd:c25:c25:94de:4d08/1282c19:dd:d9:dd:c25:c25:94de:4d08
102c19:dd:d9:dd:c25:c25:94de:4d09/1282c19:dd:d9:dd:c25:c25:94de:4d09
112c19:dd:d9:dd:c25:c25:94de:4d0a/1282c19:dd:d9:dd:c25:c25:94de:4d0a
122c19:dd:d9:dd:c25:c25:94de:4d0b/1282c19:dd:d9:dd:c25:c25:94de:4d0b
132c19:dd:d9:dd:c25:c25:94de:4d0c/1282c19:dd:d9:dd:c25:c25:94de:4d0c
142c19:dd:d9:dd:c25:c25:94de:4d0d/1282c19:dd:d9:dd:c25:c25:94de:4d0d
152c19:dd:d9:dd:c25:c25:94de:4d0e/1282c19:dd:d9:dd:c25:c25:94de:4d0e
162c19:dd:d9:dd:c25:c25:94de:4d0f/1282c19:dd:d9:dd:c25:c25:94de:4d0f
172c19:dd:d9:dd:c25:c25:94de:4d10/1282c19:dd:d9:dd:c25:c25:94de:4d10
182c19:dd:d9:dd:c25:c25:94de:4d11/1282c19:dd:d9:dd:c25:c25:94de:4d11
192c19:dd:d9:dd:c25:c25:94de:4d12/1282c19:dd:d9:dd:c25:c25:94de:4d12
202c19:dd:d9:dd:c25:c25:94de:4d13/1282c19:dd:d9:dd:c25:c25:94de:4d13
212c19:dd:d9:dd:c25:c25:94de:4d14/1282c19:dd:d9:dd:c25:c25:94de:4d14
222c19:dd:d9:dd:c25:c25:94de:4d15/1282c19:dd:d9:dd:c25:c25:94de:4d15
232c19:dd:d9:dd:c25:c25:94de:4d16/1282c19:dd:d9:dd:c25:c25:94de:4d16
242c19:dd:d9:dd:c25:c25:94de:4d17/1282c19:dd:d9:dd:c25:c25:94de:4d17
252c19:dd:d9:dd:c25:c25:94de:4d18/1282c19:dd:d9:dd:c25:c25:94de:4d18
262c19:dd:d9:dd:c25:c25:94de:4d19/1282c19:dd:d9:dd:c25:c25:94de:4d19
272c19:dd:d9:dd:c25:c25:94de:4d1a/1282c19:dd:d9:dd:c25:c25:94de:4d1a
282c19:dd:d9:dd:c25:c25:94de:4d1b/1282c19:dd:d9:dd:c25:c25:94de:4d1b
292c19:dd:d9:dd:c25:c25:94de:4d1c/1282c19:dd:d9:dd:c25:c25:94de:4d1c
302c19:dd:d9:dd:c25:c25:94de:4d1d/1282c19:dd:d9:dd:c25:c25:94de:4d1d
312c19:dd:d9:dd:c25:c25:94de:4d1e/1282c19:dd:d9:dd:c25:c25:94de:4d1e
322c19:dd:d9:dd:c25:c25:94de:4d1f/1282c19:dd:d9:dd:c25:c25:94de:4d1f
332c19:dd:d9:dd:c25:c25:94de:4d20/1282c19:dd:d9:dd:c25:c25:94de:4d20
342c19:dd:d9:dd:c25:c25:94de:4d21/1282c19:dd:d9:dd:c25:c25:94de:4d21
352c19:dd:d9:dd:c25:c25:94de:4d22/1282c19:dd:d9:dd:c25:c25:94de:4d22
362c19:dd:d9:dd:c25:c25:94de:4d23/1282c19:dd:d9:dd:c25:c25:94de:4d23
372c19:dd:d9:dd:c25:c25:94de:4d24/1282c19:dd:d9:dd:c25:c25:94de:4d24
382c19:dd:d9:dd:c25:c25:94de:4d25/1282c19:dd:d9:dd:c25:c25:94de:4d25
392c19:dd:d9:dd:c25:c25:94de:4d26/1282c19:dd:d9:dd:c25:c25:94de:4d26
402c19:dd:d9:dd:c25:c25:94de:4d27/1282c19:dd:d9:dd:c25:c25:94de:4d27
412c19:dd:d9:dd:c25:c25:94de:4d28/1282c19:dd:d9:dd:c25:c25:94de:4d28
422c19:dd:d9:dd:c25:c25:94de:4d29/1282c19:dd:d9:dd:c25:c25:94de:4d29
432c19:dd:d9:dd:c25:c25:94de:4d2a/1282c19:dd:d9:dd:c25:c25:94de:4d2a
442c19:dd:d9:dd:c25:c25:94de:4d2b/1282c19:dd:d9:dd:c25:c25:94de:4d2b
452c19:dd:d9:dd:c25:c25:94de:4d2c/1282c19:dd:d9:dd:c25:c25:94de:4d2c
462c19:dd:d9:dd:c25:c25:94de:4d2d/1282c19:dd:d9:dd:c25:c25:94de:4d2d
472c19:dd:d9:dd:c25:c25:94de:4d2e/1282c19:dd:d9:dd:c25:c25:94de:4d2e
482c19:dd:d9:dd:c25:c25:94de:4d2f/1282c19:dd:d9:dd:c25:c25:94de:4d2f
492c19:dd:d9:dd:c25:c25:94de:4d30/1282c19:dd:d9:dd:c25:c25:94de:4d30
502c19:dd:d9:dd:c25:c25:94de:4d31/1282c19:dd:d9:dd:c25:c25:94de:4d31
512c19:dd:d9:dd:c25:c25:94de:4d32/1282c19:dd:d9:dd:c25:c25:94de:4d32
522c19:dd:d9:dd:c25:c25:94de:4d33/1282c19:dd:d9:dd:c25:c25:94de:4d33
532c19:dd:d9:dd:c25:c25:94de:4d34/1282c19:dd:d9:dd:c25:c25:94de:4d34
542c19:dd:d9:dd:c25:c25:94de:4d35/1282c19:dd:d9:dd:c25:c25:94de:4d35
552c19:dd:d9:dd:c25:c25:94de:4d36/1282c19:dd:d9:dd:c25:c25:94de:4d36
562c19:dd:d9:dd:c25:c25:94de:4d37/1282c19:dd:d9:dd:c25:c25:94de:4d37
572c19:dd:d9:dd:c25:c25:94de:4d38/1282c19:dd:d9:dd:c25:c25:94de:4d38
582c19:dd:d9:dd:c25:c25:94de:4d39/1282c19:dd:d9:dd:c25:c25:94de:4d39
592c19:dd:d9:dd:c25:c25:94de:4d3a/1282c19:dd:d9:dd:c25:c25:94de:4d3a
602c19:dd:d9:dd:c25:c25:94de:4d3b/1282c19:dd:d9:dd:c25:c25:94de:4d3b
612c19:dd:d9:dd:c25:c25:94de:4d3c/1282c19:dd:d9:dd:c25:c25:94de:4d3c
622c19:dd:d9:dd:c25:c25:94de:4d3d/1282c19:dd:d9:dd:c25:c25:94de:4d3d
632c19:dd:d9:dd:c25:c25:94de:4d3e/1282c19:dd:d9:dd:c25:c25:94de:4d3e
642c19:dd:d9:dd:c25:c25:94de:4d3f/1282c19:dd:d9:dd:c25:c25:94de:4d3f
652c19:dd:d9:dd:c25:c25:94de:4d40/1282c19:dd:d9:dd:c25:c25:94de:4d40
662c19:dd:d9:dd:c25:c25:94de:4d41/1282c19:dd:d9:dd:c25:c25:94de:4d41
672c19:dd:d9:dd:c25:c25:94de:4d42/1282c19:dd:d9:dd:c25:c25:94de:4d42
682c19:dd:d9:dd:c25:c25:94de:4d43/1282c19:dd:d9:dd:c25:c25:94de:4d43
692c19:dd:d9:dd:c25:c25:94de:4d44/1282c19:dd:d9:dd:c25:c25:94de:4d44
702c19:dd:d9:dd:c25:c25:94de:4d45/1282c19:dd:d9:dd:c25:c25:94de:4d45
712c19:dd:d9:dd:c25:c25:94de:4d46/1282c19:dd:d9:dd:c25:c25:94de:4d46
722c19:dd:d9:dd:c25:c25:94de:4d47/1282c19:dd:d9:dd:c25:c25:94de:4d47
732c19:dd:d9:dd:c25:c25:94de:4d48/1282c19:dd:d9:dd:c25:c25:94de:4d48
742c19:dd:d9:dd:c25:c25:94de:4d49/1282c19:dd:d9:dd:c25:c25:94de:4d49
752c19:dd:d9:dd:c25:c25:94de:4d4a/1282c19:dd:d9:dd:c25:c25:94de:4d4a
762c19:dd:d9:dd:c25:c25:94de:4d4b/1282c19:dd:d9:dd:c25:c25:94de:4d4b
772c19:dd:d9:dd:c25:c25:94de:4d4c/1282c19:dd:d9:dd:c25:c25:94de:4d4c
782c19:dd:d9:dd:c25:c25:94de:4d4d/1282c19:dd:d9:dd:c25:c25:94de:4d4d
792c19:dd:d9:dd:c25:c25:94de:4d4e/1282c19:dd:d9:dd:c25:c25:94de:4d4e
802c19:dd:d9:dd:c25:c25:94de:4d4f/1282c19:dd:d9:dd:c25:c25:94de:4d4f
812c19:dd:d9:dd:c25:c25:94de:4d50/1282c19:dd:d9:dd:c25:c25:94de:4d50
822c19:dd:d9:dd:c25:c25:94de:4d51/1282c19:dd:d9:dd:c25:c25:94de:4d51
832c19:dd:d9:dd:c25:c25:94de:4d52/1282c19:dd:d9:dd:c25:c25:94de:4d52
842c19:dd:d9:dd:c25:c25:94de:4d53/1282c19:dd:d9:dd:c25:c25:94de:4d53
852c19:dd:d9:dd:c25:c25:94de:4d54/1282c19:dd:d9:dd:c25:c25:94de:4d54
862c19:dd:d9:dd:c25:c25:94de:4d55/1282c19:dd:d9:dd:c25:c25:94de:4d55
872c19:dd:d9:dd:c25:c25:94de:4d56/1282c19:dd:d9:dd:c25:c25:94de:4d56
882c19:dd:d9:dd:c25:c25:94de:4d57/1282c19:dd:d9:dd:c25:c25:94de:4d57
892c19:dd:d9:dd:c25:c25:94de:4d58/1282c19:dd:d9:dd:c25:c25:94de:4d58
902c19:dd:d9:dd:c25:c25:94de:4d59/1282c19:dd:d9:dd:c25:c25:94de:4d59
912c19:dd:d9:dd:c25:c25:94de:4d5a/1282c19:dd:d9:dd:c25:c25:94de:4d5a
922c19:dd:d9:dd:c25:c25:94de:4d5b/1282c19:dd:d9:dd:c25:c25:94de:4d5b
932c19:dd:d9:dd:c25:c25:94de:4d5c/1282c19:dd:d9:dd:c25:c25:94de:4d5c
942c19:dd:d9:dd:c25:c25:94de:4d5d/1282c19:dd:d9:dd:c25:c25:94de:4d5d
952c19:dd:d9:dd:c25:c25:94de:4d5e/1282c19:dd:d9:dd:c25:c25:94de:4d5e
962c19:dd:d9:dd:c25:c25:94de:4d5f/1282c19:dd:d9:dd:c25:c25:94de:4d5f
972c19:dd:d9:dd:c25:c25:94de:4d60/1282c19:dd:d9:dd:c25:c25:94de:4d60
982c19:dd:d9:dd:c25:c25:94de:4d61/1282c19:dd:d9:dd:c25:c25:94de:4d61
992c19:dd:d9:dd:c25:c25:94de:4d62/1282c19:dd:d9:dd:c25:c25:94de:4d62
1002c19:dd:d9:dd:c25:c25:94de:4d63/1282c19:dd:d9:dd:c25:c25:94de:4d63
1012c19:dd:d9:dd:c25:c25:94de:4d64/1282c19:dd:d9:dd:c25:c25:94de:4d64
1022c19:dd:d9:dd:c25:c25:94de:4d65/1282c19:dd:d9:dd:c25:c25:94de:4d65
1032c19:dd:d9:dd:c25:c25:94de:4d66/1282c19:dd:d9:dd:c25:c25:94de:4d66
1042c19:dd:d9:dd:c25:c25:94de:4d67/1282c19:dd:d9:dd:c25:c25:94de:4d67
1052c19:dd:d9:dd:c25:c25:94de:4d68/1282c19:dd:d9:dd:c25:c25:94de:4d68
1062c19:dd:d9:dd:c25:c25:94de:4d69/1282c19:dd:d9:dd:c25:c25:94de:4d69
1072c19:dd:d9:dd:c25:c25:94de:4d6a/1282c19:dd:d9:dd:c25:c25:94de:4d6a
1082c19:dd:d9:dd:c25:c25:94de:4d6b/1282c19:dd:d9:dd:c25:c25:94de:4d6b
1092c19:dd:d9:dd:c25:c25:94de:4d6c/1282c19:dd:d9:dd:c25:c25:94de:4d6c
1102c19:dd:d9:dd:c25:c25:94de:4d6d/1282c19:dd:d9:dd:c25:c25:94de:4d6d
1112c19:dd:d9:dd:c25:c25:94de:4d6e/1282c19:dd:d9:dd:c25:c25:94de:4d6e
1122c19:dd:d9:dd:c25:c25:94de:4d6f/1282c19:dd:d9:dd:c25:c25:94de:4d6f
1132c19:dd:d9:dd:c25:c25:94de:4d70/1282c19:dd:d9:dd:c25:c25:94de:4d70
1142c19:dd:d9:dd:c25:c25:94de:4d71/1282c19:dd:d9:dd:c25:c25:94de:4d71
1152c19:dd:d9:dd:c25:c25:94de:4d72/1282c19:dd:d9:dd:c25:c25:94de:4d72
1162c19:dd:d9:dd:c25:c25:94de:4d73/1282c19:dd:d9:dd:c25:c25:94de:4d73
1172c19:dd:d9:dd:c25:c25:94de:4d74/1282c19:dd:d9:dd:c25:c25:94de:4d74
1182c19:dd:d9:dd:c25:c25:94de:4d75/1282c19:dd:d9:dd:c25:c25:94de:4d75
1192c19:dd:d9:dd:c25:c25:94de:4d76/1282c19:dd:d9:dd:c25:c25:94de:4d76
1202c19:dd:d9:dd:c25:c25:94de:4d77/1282c19:dd:d9:dd:c25:c25:94de:4d77
1212c19:dd:d9:dd:c25:c25:94de:4d78/1282c19:dd:d9:dd:c25:c25:94de:4d78
1222c19:dd:d9:dd:c25:c25:94de:4d79/1282c19:dd:d9:dd:c25:c25:94de:4d79
1232c19:dd:d9:dd:c25:c25:94de:4d7a/1282c19:dd:d9:dd:c25:c25:94de:4d7a
1242c19:dd:d9:dd:c25:c25:94de:4d7b/1282c19:dd:d9:dd:c25:c25:94de:4d7b
1252c19:dd:d9:dd:c25:c25:94de:4d7c/1282c19:dd:d9:dd:c25:c25:94de:4d7c
1262c19:dd:d9:dd:c25:c25:94de:4d7d/1282c19:dd:d9:dd:c25:c25:94de:4d7d
1272c19:dd:d9:dd:c25:c25:94de:4d7e/1282c19:dd:d9:dd:c25:c25:94de:4d7e
1282c19:dd:d9:dd:c25:c25:94de:4d7f/1282c19:dd:d9:dd:c25:c25:94de:4d7f
1292c19:dd:d9:dd:c25:c25:94de:4d80/1282c19:dd:d9:dd:c25:c25:94de:4d80
1302c19:dd:d9:dd:c25:c25:94de:4d81/1282c19:dd:d9:dd:c25:c25:94de:4d81
1312c19:dd:d9:dd:c25:c25:94de:4d82/1282c19:dd:d9:dd:c25:c25:94de:4d82
1322c19:dd:d9:dd:c25:c25:94de:4d83/1282c19:dd:d9:dd:c25:c25:94de:4d83
1332c19:dd:d9:dd:c25:c25:94de:4d84/1282c19:dd:d9:dd:c25:c25:94de:4d84
1342c19:dd:d9:dd:c25:c25:94de:4d85/1282c19:dd:d9:dd:c25:c25:94de:4d85
1352c19:dd:d9:dd:c25:c25:94de:4d86/1282c19:dd:d9:dd:c25:c25:94de:4d86
1362c19:dd:d9:dd:c25:c25:94de:4d87/1282c19:dd:d9:dd:c25:c25:94de:4d87
1372c19:dd:d9:dd:c25:c25:94de:4d88/1282c19:dd:d9:dd:c25:c25:94de:4d88
1382c19:dd:d9:dd:c25:c25:94de:4d89/1282c19:dd:d9:dd:c25:c25:94de:4d89
1392c19:dd:d9:dd:c25:c25:94de:4d8a/1282c19:dd:d9:dd:c25:c25:94de:4d8a
1402c19:dd:d9:dd:c25:c25:94de:4d8b/1282c19:dd:d9:dd:c25:c25:94de:4d8b
1412c19:dd:d9:dd:c25:c25:94de:4d8c/1282c19:dd:d9:dd:c25:c25:94de:4d8c
1422c19:dd:d9:dd:c25:c25:94de:4d8d/1282c19:dd:d9:dd:c25:c25:94de:4d8d
1432c19:dd:d9:dd:c25:c25:94de:4d8e/1282c19:dd:d9:dd:c25:c25:94de:4d8e
1442c19:dd:d9:dd:c25:c25:94de:4d8f/1282c19:dd:d9:dd:c25:c25:94de:4d8f
1452c19:dd:d9:dd:c25:c25:94de:4d90/1282c19:dd:d9:dd:c25:c25:94de:4d90
1462c19:dd:d9:dd:c25:c25:94de:4d91/1282c19:dd:d9:dd:c25:c25:94de:4d91
1472c19:dd:d9:dd:c25:c25:94de:4d92/1282c19:dd:d9:dd:c25:c25:94de:4d92
1482c19:dd:d9:dd:c25:c25:94de:4d93/1282c19:dd:d9:dd:c25:c25:94de:4d93
1492c19:dd:d9:dd:c25:c25:94de:4d94/1282c19:dd:d9:dd:c25:c25:94de:4d94
1502c19:dd:d9:dd:c25:c25:94de:4d95/1282c19:dd:d9:dd:c25:c25:94de:4d95
1512c19:dd:d9:dd:c25:c25:94de:4d96/1282c19:dd:d9:dd:c25:c25:94de:4d96
1522c19:dd:d9:dd:c25:c25:94de:4d97/1282c19:dd:d9:dd:c25:c25:94de:4d97
1532c19:dd:d9:dd:c25:c25:94de:4d98/1282c19:dd:d9:dd:c25:c25:94de:4d98
1542c19:dd:d9:dd:c25:c25:94de:4d99/1282c19:dd:d9:dd:c25:c25:94de:4d99
1552c19:dd:d9:dd:c25:c25:94de:4d9a/1282c19:dd:d9:dd:c25:c25:94de:4d9a
1562c19:dd:d9:dd:c25:c25:94de:4d9b/1282c19:dd:d9:dd:c25:c25:94de:4d9b
1572c19:dd:d9:dd:c25:c25:94de:4d9c/1282c19:dd:d9:dd:c25:c25:94de:4d9c
1582c19:dd:d9:dd:c25:c25:94de:4d9d/1282c19:dd:d9:dd:c25:c25:94de:4d9d
1592c19:dd:d9:dd:c25:c25:94de:4d9e/1282c19:dd:d9:dd:c25:c25:94de:4d9e
1602c19:dd:d9:dd:c25:c25:94de:4d9f/1282c19:dd:d9:dd:c25:c25:94de:4d9f
1612c19:dd:d9:dd:c25:c25:94de:4da0/1282c19:dd:d9:dd:c25:c25:94de:4da0
1622c19:dd:d9:dd:c25:c25:94de:4da1/1282c19:dd:d9:dd:c25:c25:94de:4da1
1632c19:dd:d9:dd:c25:c25:94de:4da2/1282c19:dd:d9:dd:c25:c25:94de:4da2
1642c19:dd:d9:dd:c25:c25:94de:4da3/1282c19:dd:d9:dd:c25:c25:94de:4da3
1652c19:dd:d9:dd:c25:c25:94de:4da4/1282c19:dd:d9:dd:c25:c25:94de:4da4
1662c19:dd:d9:dd:c25:c25:94de:4da5/1282c19:dd:d9:dd:c25:c25:94de:4da5
1672c19:dd:d9:dd:c25:c25:94de:4da6/1282c19:dd:d9:dd:c25:c25:94de:4da6
1682c19:dd:d9:dd:c25:c25:94de:4da7/1282c19:dd:d9:dd:c25:c25:94de:4da7
1692c19:dd:d9:dd:c25:c25:94de:4da8/1282c19:dd:d9:dd:c25:c25:94de:4da8
1702c19:dd:d9:dd:c25:c25:94de:4da9/1282c19:dd:d9:dd:c25:c25:94de:4da9
1712c19:dd:d9:dd:c25:c25:94de:4daa/1282c19:dd:d9:dd:c25:c25:94de:4daa
1722c19:dd:d9:dd:c25:c25:94de:4dab/1282c19:dd:d9:dd:c25:c25:94de:4dab
1732c19:dd:d9:dd:c25:c25:94de:4dac/1282c19:dd:d9:dd:c25:c25:94de:4dac
1742c19:dd:d9:dd:c25:c25:94de:4dad/1282c19:dd:d9:dd:c25:c25:94de:4dad
1752c19:dd:d9:dd:c25:c25:94de:4dae/1282c19:dd:d9:dd:c25:c25:94de:4dae
1762c19:dd:d9:dd:c25:c25:94de:4daf/1282c19:dd:d9:dd:c25:c25:94de:4daf
1772c19:dd:d9:dd:c25:c25:94de:4db0/1282c19:dd:d9:dd:c25:c25:94de:4db0
1782c19:dd:d9:dd:c25:c25:94de:4db1/1282c19:dd:d9:dd:c25:c25:94de:4db1
1792c19:dd:d9:dd:c25:c25:94de:4db2/1282c19:dd:d9:dd:c25:c25:94de:4db2
1802c19:dd:d9:dd:c25:c25:94de:4db3/1282c19:dd:d9:dd:c25:c25:94de:4db3
1812c19:dd:d9:dd:c25:c25:94de:4db4/1282c19:dd:d9:dd:c25:c25:94de:4db4
1822c19:dd:d9:dd:c25:c25:94de:4db5/1282c19:dd:d9:dd:c25:c25:94de:4db5
1832c19:dd:d9:dd:c25:c25:94de:4db6/1282c19:dd:d9:dd:c25:c25:94de:4db6
1842c19:dd:d9:dd:c25:c25:94de:4db7/1282c19:dd:d9:dd:c25:c25:94de:4db7
1852c19:dd:d9:dd:c25:c25:94de:4db8/1282c19:dd:d9:dd:c25:c25:94de:4db8
1862c19:dd:d9:dd:c25:c25:94de:4db9/1282c19:dd:d9:dd:c25:c25:94de:4db9
1872c19:dd:d9:dd:c25:c25:94de:4dba/1282c19:dd:d9:dd:c25:c25:94de:4dba
1882c19:dd:d9:dd:c25:c25:94de:4dbb/1282c19:dd:d9:dd:c25:c25:94de:4dbb
1892c19:dd:d9:dd:c25:c25:94de:4dbc/1282c19:dd:d9:dd:c25:c25:94de:4dbc
1902c19:dd:d9:dd:c25:c25:94de:4dbd/1282c19:dd:d9:dd:c25:c25:94de:4dbd
1912c19:dd:d9:dd:c25:c25:94de:4dbe/1282c19:dd:d9:dd:c25:c25:94de:4dbe
1922c19:dd:d9:dd:c25:c25:94de:4dbf/1282c19:dd:d9:dd:c25:c25:94de:4dbf
1932c19:dd:d9:dd:c25:c25:94de:4dc0/1282c19:dd:d9:dd:c25:c25:94de:4dc0
1942c19:dd:d9:dd:c25:c25:94de:4dc1/1282c19:dd:d9:dd:c25:c25:94de:4dc1
1952c19:dd:d9:dd:c25:c25:94de:4dc2/1282c19:dd:d9:dd:c25:c25:94de:4dc2
1962c19:dd:d9:dd:c25:c25:94de:4dc3/1282c19:dd:d9:dd:c25:c25:94de:4dc3
1972c19:dd:d9:dd:c25:c25:94de:4dc4/1282c19:dd:d9:dd:c25:c25:94de:4dc4
1982c19:dd:d9:dd:c25:c25:94de:4dc5/1282c19:dd:d9:dd:c25:c25:94de:4dc5
1992c19:dd:d9:dd:c25:c25:94de:4dc6/1282c19:dd:d9:dd:c25:c25:94de:4dc6
2002c19:dd:d9:dd:c25:c25:94de:4dc7/1282c19:dd:d9:dd:c25:c25:94de:4dc7
2012c19:dd:d9:dd:c25:c25:94de:4dc8/1282c19:dd:d9:dd:c25:c25:94de:4dc8
2022c19:dd:d9:dd:c25:c25:94de:4dc9/1282c19:dd:d9:dd:c25:c25:94de:4dc9
2032c19:dd:d9:dd:c25:c25:94de:4dca/1282c19:dd:d9:dd:c25:c25:94de:4dca
2042c19:dd:d9:dd:c25:c25:94de:4dcb/1282c19:dd:d9:dd:c25:c25:94de:4dcb
2052c19:dd:d9:dd:c25:c25:94de:4dcc/1282c19:dd:d9:dd:c25:c25:94de:4dcc
2062c19:dd:d9:dd:c25:c25:94de:4dcd/1282c19:dd:d9:dd:c25:c25:94de:4dcd
2072c19:dd:d9:dd:c25:c25:94de:4dce/1282c19:dd:d9:dd:c25:c25:94de:4dce
2082c19:dd:d9:dd:c25:c25:94de:4dcf/1282c19:dd:d9:dd:c25:c25:94de:4dcf
2092c19:dd:d9:dd:c25:c25:94de:4dd0/1282c19:dd:d9:dd:c25:c25:94de:4dd0
2102c19:dd:d9:dd:c25:c25:94de:4dd1/1282c19:dd:d9:dd:c25:c25:94de:4dd1
2112c19:dd:d9:dd:c25:c25:94de:4dd2/1282c19:dd:d9:dd:c25:c25:94de:4dd2
2122c19:dd:d9:dd:c25:c25:94de:4dd3/1282c19:dd:d9:dd:c25:c25:94de:4dd3
2132c19:dd:d9:dd:c25:c25:94de:4dd4/1282c19:dd:d9:dd:c25:c25:94de:4dd4
2142c19:dd:d9:dd:c25:c25:94de:4dd5/1282c19:dd:d9:dd:c25:c25:94de:4dd5
2152c19:dd:d9:dd:c25:c25:94de:4dd6/1282c19:dd:d9:dd:c25:c25:94de:4dd6
2162c19:dd:d9:dd:c25:c25:94de:4dd7/1282c19:dd:d9:dd:c25:c25:94de:4dd7
2172c19:dd:d9:dd:c25:c25:94de:4dd8/1282c19:dd:d9:dd:c25:c25:94de:4dd8
2182c19:dd:d9:dd:c25:c25:94de:4dd9/1282c19:dd:d9:dd:c25:c25:94de:4dd9
2192c19:dd:d9:dd:c25:c25:94de:4dda/1282c19:dd:d9:dd:c25:c25:94de:4dda
2202c19:dd:d9:dd:c25:c25:94de:4ddb/1282c19:dd:d9:dd:c25:c25:94de:4ddb
2212c19:dd:d9:dd:c25:c25:94de:4ddc/1282c19:dd:d9:dd:c25:c25:94de:4ddc
2222c19:dd:d9:dd:c25:c25:94de:4ddd/1282c19:dd:d9:dd:c25:c25:94de:4ddd
2232c19:dd:d9:dd:c25:c25:94de:4dde/1282c19:dd:d9:dd:c25:c25:94de:4dde
2242c19:dd:d9:dd:c25:c25:94de:4ddf/1282c19:dd:d9:dd:c25:c25:94de:4ddf
2252c19:dd:d9:dd:c25:c25:94de:4de0/1282c19:dd:d9:dd:c25:c25:94de:4de0
2262c19:dd:d9:dd:c25:c25:94de:4de1/1282c19:dd:d9:dd:c25:c25:94de:4de1
2272c19:dd:d9:dd:c25:c25:94de:4de2/1282c19:dd:d9:dd:c25:c25:94de:4de2
2282c19:dd:d9:dd:c25:c25:94de:4de3/1282c19:dd:d9:dd:c25:c25:94de:4de3
2292c19:dd:d9:dd:c25:c25:94de:4de4/1282c19:dd:d9:dd:c25:c25:94de:4de4
2302c19:dd:d9:dd:c25:c25:94de:4de5/1282c19:dd:d9:dd:c25:c25:94de:4de5
2312c19:dd:d9:dd:c25:c25:94de:4de6/1282c19:dd:d9:dd:c25:c25:94de:4de6
2322c19:dd:d9:dd:c25:c25:94de:4de7/1282c19:dd:d9:dd:c25:c25:94de:4de7
2332c19:dd:d9:dd:c25:c25:94de:4de8/1282c19:dd:d9:dd:c25:c25:94de:4de8
2342c19:dd:d9:dd:c25:c25:94de:4de9/1282c19:dd:d9:dd:c25:c25:94de:4de9
2352c19:dd:d9:dd:c25:c25:94de:4dea/1282c19:dd:d9:dd:c25:c25:94de:4dea
2362c19:dd:d9:dd:c25:c25:94de:4deb/1282c19:dd:d9:dd:c25:c25:94de:4deb
2372c19:dd:d9:dd:c25:c25:94de:4dec/1282c19:dd:d9:dd:c25:c25:94de:4dec
2382c19:dd:d9:dd:c25:c25:94de:4ded/1282c19:dd:d9:dd:c25:c25:94de:4ded
2392c19:dd:d9:dd:c25:c25:94de:4dee/1282c19:dd:d9:dd:c25:c25:94de:4dee
2402c19:dd:d9:dd:c25:c25:94de:4def/1282c19:dd:d9:dd:c25:c25:94de:4def
2412c19:dd:d9:dd:c25:c25:94de:4df0/1282c19:dd:d9:dd:c25:c25:94de:4df0
2422c19:dd:d9:dd:c25:c25:94de:4df1/1282c19:dd:d9:dd:c25:c25:94de:4df1
2432c19:dd:d9:dd:c25:c25:94de:4df2/1282c19:dd:d9:dd:c25:c25:94de:4df2
2442c19:dd:d9:dd:c25:c25:94de:4df3/1282c19:dd:d9:dd:c25:c25:94de:4df3
2452c19:dd:d9:dd:c25:c25:94de:4df4/1282c19:dd:d9:dd:c25:c25:94de:4df4
2462c19:dd:d9:dd:c25:c25:94de:4df5/1282c19:dd:d9:dd:c25:c25:94de:4df5
2472c19:dd:d9:dd:c25:c25:94de:4df6/1282c19:dd:d9:dd:c25:c25:94de:4df6
2482c19:dd:d9:dd:c25:c25:94de:4df7/1282c19:dd:d9:dd:c25:c25:94de:4df7
2492c19:dd:d9:dd:c25:c25:94de:4df8/1282c19:dd:d9:dd:c25:c25:94de:4df8
2502c19:dd:d9:dd:c25:c25:94de:4df9/1282c19:dd:d9:dd:c25:c25:94de:4df9
2512c19:dd:d9:dd:c25:c25:94de:4dfa/1282c19:dd:d9:dd:c25:c25:94de:4dfa
2522c19:dd:d9:dd:c25:c25:94de:4dfb/1282c19:dd:d9:dd:c25:c25:94de:4dfb
2532c19:dd:d9:dd:c25:c25:94de:4dfc/1282c19:dd:d9:dd:c25:c25:94de:4dfc
2542c19:dd:d9:dd:c25:c25:94de:4dfd/1282c19:dd:d9:dd:c25:c25:94de:4dfd
2552c19:dd:d9:dd:c25:c25:94de:4dfe/1282c19:dd:d9:dd:c25:c25:94de:4dfe
2562c19:dd:d9:dd:c25:c25:94de:4dff/1282c19:dd:d9:dd:c25:c25:94de:4dff

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.