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:d9be:ea00/120
First address
2c19:dd:d9:dd:c25:c25:d9be:ea00
Last address
2c19:dd:d9:dd:c25:c25:d9be:eaff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:d9be:ea00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
a.e.e.b.9.d.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:d9be:ea00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:d9be:ea00/1282c19:dd:d9:dd:c25:c25:d9be:ea00
22c19:dd:d9:dd:c25:c25:d9be:ea01/1282c19:dd:d9:dd:c25:c25:d9be:ea01
32c19:dd:d9:dd:c25:c25:d9be:ea02/1282c19:dd:d9:dd:c25:c25:d9be:ea02
42c19:dd:d9:dd:c25:c25:d9be:ea03/1282c19:dd:d9:dd:c25:c25:d9be:ea03
52c19:dd:d9:dd:c25:c25:d9be:ea04/1282c19:dd:d9:dd:c25:c25:d9be:ea04
62c19:dd:d9:dd:c25:c25:d9be:ea05/1282c19:dd:d9:dd:c25:c25:d9be:ea05
72c19:dd:d9:dd:c25:c25:d9be:ea06/1282c19:dd:d9:dd:c25:c25:d9be:ea06
82c19:dd:d9:dd:c25:c25:d9be:ea07/1282c19:dd:d9:dd:c25:c25:d9be:ea07
92c19:dd:d9:dd:c25:c25:d9be:ea08/1282c19:dd:d9:dd:c25:c25:d9be:ea08
102c19:dd:d9:dd:c25:c25:d9be:ea09/1282c19:dd:d9:dd:c25:c25:d9be:ea09
112c19:dd:d9:dd:c25:c25:d9be:ea0a/1282c19:dd:d9:dd:c25:c25:d9be:ea0a
122c19:dd:d9:dd:c25:c25:d9be:ea0b/1282c19:dd:d9:dd:c25:c25:d9be:ea0b
132c19:dd:d9:dd:c25:c25:d9be:ea0c/1282c19:dd:d9:dd:c25:c25:d9be:ea0c
142c19:dd:d9:dd:c25:c25:d9be:ea0d/1282c19:dd:d9:dd:c25:c25:d9be:ea0d
152c19:dd:d9:dd:c25:c25:d9be:ea0e/1282c19:dd:d9:dd:c25:c25:d9be:ea0e
162c19:dd:d9:dd:c25:c25:d9be:ea0f/1282c19:dd:d9:dd:c25:c25:d9be:ea0f
172c19:dd:d9:dd:c25:c25:d9be:ea10/1282c19:dd:d9:dd:c25:c25:d9be:ea10
182c19:dd:d9:dd:c25:c25:d9be:ea11/1282c19:dd:d9:dd:c25:c25:d9be:ea11
192c19:dd:d9:dd:c25:c25:d9be:ea12/1282c19:dd:d9:dd:c25:c25:d9be:ea12
202c19:dd:d9:dd:c25:c25:d9be:ea13/1282c19:dd:d9:dd:c25:c25:d9be:ea13
212c19:dd:d9:dd:c25:c25:d9be:ea14/1282c19:dd:d9:dd:c25:c25:d9be:ea14
222c19:dd:d9:dd:c25:c25:d9be:ea15/1282c19:dd:d9:dd:c25:c25:d9be:ea15
232c19:dd:d9:dd:c25:c25:d9be:ea16/1282c19:dd:d9:dd:c25:c25:d9be:ea16
242c19:dd:d9:dd:c25:c25:d9be:ea17/1282c19:dd:d9:dd:c25:c25:d9be:ea17
252c19:dd:d9:dd:c25:c25:d9be:ea18/1282c19:dd:d9:dd:c25:c25:d9be:ea18
262c19:dd:d9:dd:c25:c25:d9be:ea19/1282c19:dd:d9:dd:c25:c25:d9be:ea19
272c19:dd:d9:dd:c25:c25:d9be:ea1a/1282c19:dd:d9:dd:c25:c25:d9be:ea1a
282c19:dd:d9:dd:c25:c25:d9be:ea1b/1282c19:dd:d9:dd:c25:c25:d9be:ea1b
292c19:dd:d9:dd:c25:c25:d9be:ea1c/1282c19:dd:d9:dd:c25:c25:d9be:ea1c
302c19:dd:d9:dd:c25:c25:d9be:ea1d/1282c19:dd:d9:dd:c25:c25:d9be:ea1d
312c19:dd:d9:dd:c25:c25:d9be:ea1e/1282c19:dd:d9:dd:c25:c25:d9be:ea1e
322c19:dd:d9:dd:c25:c25:d9be:ea1f/1282c19:dd:d9:dd:c25:c25:d9be:ea1f
332c19:dd:d9:dd:c25:c25:d9be:ea20/1282c19:dd:d9:dd:c25:c25:d9be:ea20
342c19:dd:d9:dd:c25:c25:d9be:ea21/1282c19:dd:d9:dd:c25:c25:d9be:ea21
352c19:dd:d9:dd:c25:c25:d9be:ea22/1282c19:dd:d9:dd:c25:c25:d9be:ea22
362c19:dd:d9:dd:c25:c25:d9be:ea23/1282c19:dd:d9:dd:c25:c25:d9be:ea23
372c19:dd:d9:dd:c25:c25:d9be:ea24/1282c19:dd:d9:dd:c25:c25:d9be:ea24
382c19:dd:d9:dd:c25:c25:d9be:ea25/1282c19:dd:d9:dd:c25:c25:d9be:ea25
392c19:dd:d9:dd:c25:c25:d9be:ea26/1282c19:dd:d9:dd:c25:c25:d9be:ea26
402c19:dd:d9:dd:c25:c25:d9be:ea27/1282c19:dd:d9:dd:c25:c25:d9be:ea27
412c19:dd:d9:dd:c25:c25:d9be:ea28/1282c19:dd:d9:dd:c25:c25:d9be:ea28
422c19:dd:d9:dd:c25:c25:d9be:ea29/1282c19:dd:d9:dd:c25:c25:d9be:ea29
432c19:dd:d9:dd:c25:c25:d9be:ea2a/1282c19:dd:d9:dd:c25:c25:d9be:ea2a
442c19:dd:d9:dd:c25:c25:d9be:ea2b/1282c19:dd:d9:dd:c25:c25:d9be:ea2b
452c19:dd:d9:dd:c25:c25:d9be:ea2c/1282c19:dd:d9:dd:c25:c25:d9be:ea2c
462c19:dd:d9:dd:c25:c25:d9be:ea2d/1282c19:dd:d9:dd:c25:c25:d9be:ea2d
472c19:dd:d9:dd:c25:c25:d9be:ea2e/1282c19:dd:d9:dd:c25:c25:d9be:ea2e
482c19:dd:d9:dd:c25:c25:d9be:ea2f/1282c19:dd:d9:dd:c25:c25:d9be:ea2f
492c19:dd:d9:dd:c25:c25:d9be:ea30/1282c19:dd:d9:dd:c25:c25:d9be:ea30
502c19:dd:d9:dd:c25:c25:d9be:ea31/1282c19:dd:d9:dd:c25:c25:d9be:ea31
512c19:dd:d9:dd:c25:c25:d9be:ea32/1282c19:dd:d9:dd:c25:c25:d9be:ea32
522c19:dd:d9:dd:c25:c25:d9be:ea33/1282c19:dd:d9:dd:c25:c25:d9be:ea33
532c19:dd:d9:dd:c25:c25:d9be:ea34/1282c19:dd:d9:dd:c25:c25:d9be:ea34
542c19:dd:d9:dd:c25:c25:d9be:ea35/1282c19:dd:d9:dd:c25:c25:d9be:ea35
552c19:dd:d9:dd:c25:c25:d9be:ea36/1282c19:dd:d9:dd:c25:c25:d9be:ea36
562c19:dd:d9:dd:c25:c25:d9be:ea37/1282c19:dd:d9:dd:c25:c25:d9be:ea37
572c19:dd:d9:dd:c25:c25:d9be:ea38/1282c19:dd:d9:dd:c25:c25:d9be:ea38
582c19:dd:d9:dd:c25:c25:d9be:ea39/1282c19:dd:d9:dd:c25:c25:d9be:ea39
592c19:dd:d9:dd:c25:c25:d9be:ea3a/1282c19:dd:d9:dd:c25:c25:d9be:ea3a
602c19:dd:d9:dd:c25:c25:d9be:ea3b/1282c19:dd:d9:dd:c25:c25:d9be:ea3b
612c19:dd:d9:dd:c25:c25:d9be:ea3c/1282c19:dd:d9:dd:c25:c25:d9be:ea3c
622c19:dd:d9:dd:c25:c25:d9be:ea3d/1282c19:dd:d9:dd:c25:c25:d9be:ea3d
632c19:dd:d9:dd:c25:c25:d9be:ea3e/1282c19:dd:d9:dd:c25:c25:d9be:ea3e
642c19:dd:d9:dd:c25:c25:d9be:ea3f/1282c19:dd:d9:dd:c25:c25:d9be:ea3f
652c19:dd:d9:dd:c25:c25:d9be:ea40/1282c19:dd:d9:dd:c25:c25:d9be:ea40
662c19:dd:d9:dd:c25:c25:d9be:ea41/1282c19:dd:d9:dd:c25:c25:d9be:ea41
672c19:dd:d9:dd:c25:c25:d9be:ea42/1282c19:dd:d9:dd:c25:c25:d9be:ea42
682c19:dd:d9:dd:c25:c25:d9be:ea43/1282c19:dd:d9:dd:c25:c25:d9be:ea43
692c19:dd:d9:dd:c25:c25:d9be:ea44/1282c19:dd:d9:dd:c25:c25:d9be:ea44
702c19:dd:d9:dd:c25:c25:d9be:ea45/1282c19:dd:d9:dd:c25:c25:d9be:ea45
712c19:dd:d9:dd:c25:c25:d9be:ea46/1282c19:dd:d9:dd:c25:c25:d9be:ea46
722c19:dd:d9:dd:c25:c25:d9be:ea47/1282c19:dd:d9:dd:c25:c25:d9be:ea47
732c19:dd:d9:dd:c25:c25:d9be:ea48/1282c19:dd:d9:dd:c25:c25:d9be:ea48
742c19:dd:d9:dd:c25:c25:d9be:ea49/1282c19:dd:d9:dd:c25:c25:d9be:ea49
752c19:dd:d9:dd:c25:c25:d9be:ea4a/1282c19:dd:d9:dd:c25:c25:d9be:ea4a
762c19:dd:d9:dd:c25:c25:d9be:ea4b/1282c19:dd:d9:dd:c25:c25:d9be:ea4b
772c19:dd:d9:dd:c25:c25:d9be:ea4c/1282c19:dd:d9:dd:c25:c25:d9be:ea4c
782c19:dd:d9:dd:c25:c25:d9be:ea4d/1282c19:dd:d9:dd:c25:c25:d9be:ea4d
792c19:dd:d9:dd:c25:c25:d9be:ea4e/1282c19:dd:d9:dd:c25:c25:d9be:ea4e
802c19:dd:d9:dd:c25:c25:d9be:ea4f/1282c19:dd:d9:dd:c25:c25:d9be:ea4f
812c19:dd:d9:dd:c25:c25:d9be:ea50/1282c19:dd:d9:dd:c25:c25:d9be:ea50
822c19:dd:d9:dd:c25:c25:d9be:ea51/1282c19:dd:d9:dd:c25:c25:d9be:ea51
832c19:dd:d9:dd:c25:c25:d9be:ea52/1282c19:dd:d9:dd:c25:c25:d9be:ea52
842c19:dd:d9:dd:c25:c25:d9be:ea53/1282c19:dd:d9:dd:c25:c25:d9be:ea53
852c19:dd:d9:dd:c25:c25:d9be:ea54/1282c19:dd:d9:dd:c25:c25:d9be:ea54
862c19:dd:d9:dd:c25:c25:d9be:ea55/1282c19:dd:d9:dd:c25:c25:d9be:ea55
872c19:dd:d9:dd:c25:c25:d9be:ea56/1282c19:dd:d9:dd:c25:c25:d9be:ea56
882c19:dd:d9:dd:c25:c25:d9be:ea57/1282c19:dd:d9:dd:c25:c25:d9be:ea57
892c19:dd:d9:dd:c25:c25:d9be:ea58/1282c19:dd:d9:dd:c25:c25:d9be:ea58
902c19:dd:d9:dd:c25:c25:d9be:ea59/1282c19:dd:d9:dd:c25:c25:d9be:ea59
912c19:dd:d9:dd:c25:c25:d9be:ea5a/1282c19:dd:d9:dd:c25:c25:d9be:ea5a
922c19:dd:d9:dd:c25:c25:d9be:ea5b/1282c19:dd:d9:dd:c25:c25:d9be:ea5b
932c19:dd:d9:dd:c25:c25:d9be:ea5c/1282c19:dd:d9:dd:c25:c25:d9be:ea5c
942c19:dd:d9:dd:c25:c25:d9be:ea5d/1282c19:dd:d9:dd:c25:c25:d9be:ea5d
952c19:dd:d9:dd:c25:c25:d9be:ea5e/1282c19:dd:d9:dd:c25:c25:d9be:ea5e
962c19:dd:d9:dd:c25:c25:d9be:ea5f/1282c19:dd:d9:dd:c25:c25:d9be:ea5f
972c19:dd:d9:dd:c25:c25:d9be:ea60/1282c19:dd:d9:dd:c25:c25:d9be:ea60
982c19:dd:d9:dd:c25:c25:d9be:ea61/1282c19:dd:d9:dd:c25:c25:d9be:ea61
992c19:dd:d9:dd:c25:c25:d9be:ea62/1282c19:dd:d9:dd:c25:c25:d9be:ea62
1002c19:dd:d9:dd:c25:c25:d9be:ea63/1282c19:dd:d9:dd:c25:c25:d9be:ea63
1012c19:dd:d9:dd:c25:c25:d9be:ea64/1282c19:dd:d9:dd:c25:c25:d9be:ea64
1022c19:dd:d9:dd:c25:c25:d9be:ea65/1282c19:dd:d9:dd:c25:c25:d9be:ea65
1032c19:dd:d9:dd:c25:c25:d9be:ea66/1282c19:dd:d9:dd:c25:c25:d9be:ea66
1042c19:dd:d9:dd:c25:c25:d9be:ea67/1282c19:dd:d9:dd:c25:c25:d9be:ea67
1052c19:dd:d9:dd:c25:c25:d9be:ea68/1282c19:dd:d9:dd:c25:c25:d9be:ea68
1062c19:dd:d9:dd:c25:c25:d9be:ea69/1282c19:dd:d9:dd:c25:c25:d9be:ea69
1072c19:dd:d9:dd:c25:c25:d9be:ea6a/1282c19:dd:d9:dd:c25:c25:d9be:ea6a
1082c19:dd:d9:dd:c25:c25:d9be:ea6b/1282c19:dd:d9:dd:c25:c25:d9be:ea6b
1092c19:dd:d9:dd:c25:c25:d9be:ea6c/1282c19:dd:d9:dd:c25:c25:d9be:ea6c
1102c19:dd:d9:dd:c25:c25:d9be:ea6d/1282c19:dd:d9:dd:c25:c25:d9be:ea6d
1112c19:dd:d9:dd:c25:c25:d9be:ea6e/1282c19:dd:d9:dd:c25:c25:d9be:ea6e
1122c19:dd:d9:dd:c25:c25:d9be:ea6f/1282c19:dd:d9:dd:c25:c25:d9be:ea6f
1132c19:dd:d9:dd:c25:c25:d9be:ea70/1282c19:dd:d9:dd:c25:c25:d9be:ea70
1142c19:dd:d9:dd:c25:c25:d9be:ea71/1282c19:dd:d9:dd:c25:c25:d9be:ea71
1152c19:dd:d9:dd:c25:c25:d9be:ea72/1282c19:dd:d9:dd:c25:c25:d9be:ea72
1162c19:dd:d9:dd:c25:c25:d9be:ea73/1282c19:dd:d9:dd:c25:c25:d9be:ea73
1172c19:dd:d9:dd:c25:c25:d9be:ea74/1282c19:dd:d9:dd:c25:c25:d9be:ea74
1182c19:dd:d9:dd:c25:c25:d9be:ea75/1282c19:dd:d9:dd:c25:c25:d9be:ea75
1192c19:dd:d9:dd:c25:c25:d9be:ea76/1282c19:dd:d9:dd:c25:c25:d9be:ea76
1202c19:dd:d9:dd:c25:c25:d9be:ea77/1282c19:dd:d9:dd:c25:c25:d9be:ea77
1212c19:dd:d9:dd:c25:c25:d9be:ea78/1282c19:dd:d9:dd:c25:c25:d9be:ea78
1222c19:dd:d9:dd:c25:c25:d9be:ea79/1282c19:dd:d9:dd:c25:c25:d9be:ea79
1232c19:dd:d9:dd:c25:c25:d9be:ea7a/1282c19:dd:d9:dd:c25:c25:d9be:ea7a
1242c19:dd:d9:dd:c25:c25:d9be:ea7b/1282c19:dd:d9:dd:c25:c25:d9be:ea7b
1252c19:dd:d9:dd:c25:c25:d9be:ea7c/1282c19:dd:d9:dd:c25:c25:d9be:ea7c
1262c19:dd:d9:dd:c25:c25:d9be:ea7d/1282c19:dd:d9:dd:c25:c25:d9be:ea7d
1272c19:dd:d9:dd:c25:c25:d9be:ea7e/1282c19:dd:d9:dd:c25:c25:d9be:ea7e
1282c19:dd:d9:dd:c25:c25:d9be:ea7f/1282c19:dd:d9:dd:c25:c25:d9be:ea7f
1292c19:dd:d9:dd:c25:c25:d9be:ea80/1282c19:dd:d9:dd:c25:c25:d9be:ea80
1302c19:dd:d9:dd:c25:c25:d9be:ea81/1282c19:dd:d9:dd:c25:c25:d9be:ea81
1312c19:dd:d9:dd:c25:c25:d9be:ea82/1282c19:dd:d9:dd:c25:c25:d9be:ea82
1322c19:dd:d9:dd:c25:c25:d9be:ea83/1282c19:dd:d9:dd:c25:c25:d9be:ea83
1332c19:dd:d9:dd:c25:c25:d9be:ea84/1282c19:dd:d9:dd:c25:c25:d9be:ea84
1342c19:dd:d9:dd:c25:c25:d9be:ea85/1282c19:dd:d9:dd:c25:c25:d9be:ea85
1352c19:dd:d9:dd:c25:c25:d9be:ea86/1282c19:dd:d9:dd:c25:c25:d9be:ea86
1362c19:dd:d9:dd:c25:c25:d9be:ea87/1282c19:dd:d9:dd:c25:c25:d9be:ea87
1372c19:dd:d9:dd:c25:c25:d9be:ea88/1282c19:dd:d9:dd:c25:c25:d9be:ea88
1382c19:dd:d9:dd:c25:c25:d9be:ea89/1282c19:dd:d9:dd:c25:c25:d9be:ea89
1392c19:dd:d9:dd:c25:c25:d9be:ea8a/1282c19:dd:d9:dd:c25:c25:d9be:ea8a
1402c19:dd:d9:dd:c25:c25:d9be:ea8b/1282c19:dd:d9:dd:c25:c25:d9be:ea8b
1412c19:dd:d9:dd:c25:c25:d9be:ea8c/1282c19:dd:d9:dd:c25:c25:d9be:ea8c
1422c19:dd:d9:dd:c25:c25:d9be:ea8d/1282c19:dd:d9:dd:c25:c25:d9be:ea8d
1432c19:dd:d9:dd:c25:c25:d9be:ea8e/1282c19:dd:d9:dd:c25:c25:d9be:ea8e
1442c19:dd:d9:dd:c25:c25:d9be:ea8f/1282c19:dd:d9:dd:c25:c25:d9be:ea8f
1452c19:dd:d9:dd:c25:c25:d9be:ea90/1282c19:dd:d9:dd:c25:c25:d9be:ea90
1462c19:dd:d9:dd:c25:c25:d9be:ea91/1282c19:dd:d9:dd:c25:c25:d9be:ea91
1472c19:dd:d9:dd:c25:c25:d9be:ea92/1282c19:dd:d9:dd:c25:c25:d9be:ea92
1482c19:dd:d9:dd:c25:c25:d9be:ea93/1282c19:dd:d9:dd:c25:c25:d9be:ea93
1492c19:dd:d9:dd:c25:c25:d9be:ea94/1282c19:dd:d9:dd:c25:c25:d9be:ea94
1502c19:dd:d9:dd:c25:c25:d9be:ea95/1282c19:dd:d9:dd:c25:c25:d9be:ea95
1512c19:dd:d9:dd:c25:c25:d9be:ea96/1282c19:dd:d9:dd:c25:c25:d9be:ea96
1522c19:dd:d9:dd:c25:c25:d9be:ea97/1282c19:dd:d9:dd:c25:c25:d9be:ea97
1532c19:dd:d9:dd:c25:c25:d9be:ea98/1282c19:dd:d9:dd:c25:c25:d9be:ea98
1542c19:dd:d9:dd:c25:c25:d9be:ea99/1282c19:dd:d9:dd:c25:c25:d9be:ea99
1552c19:dd:d9:dd:c25:c25:d9be:ea9a/1282c19:dd:d9:dd:c25:c25:d9be:ea9a
1562c19:dd:d9:dd:c25:c25:d9be:ea9b/1282c19:dd:d9:dd:c25:c25:d9be:ea9b
1572c19:dd:d9:dd:c25:c25:d9be:ea9c/1282c19:dd:d9:dd:c25:c25:d9be:ea9c
1582c19:dd:d9:dd:c25:c25:d9be:ea9d/1282c19:dd:d9:dd:c25:c25:d9be:ea9d
1592c19:dd:d9:dd:c25:c25:d9be:ea9e/1282c19:dd:d9:dd:c25:c25:d9be:ea9e
1602c19:dd:d9:dd:c25:c25:d9be:ea9f/1282c19:dd:d9:dd:c25:c25:d9be:ea9f
1612c19:dd:d9:dd:c25:c25:d9be:eaa0/1282c19:dd:d9:dd:c25:c25:d9be:eaa0
1622c19:dd:d9:dd:c25:c25:d9be:eaa1/1282c19:dd:d9:dd:c25:c25:d9be:eaa1
1632c19:dd:d9:dd:c25:c25:d9be:eaa2/1282c19:dd:d9:dd:c25:c25:d9be:eaa2
1642c19:dd:d9:dd:c25:c25:d9be:eaa3/1282c19:dd:d9:dd:c25:c25:d9be:eaa3
1652c19:dd:d9:dd:c25:c25:d9be:eaa4/1282c19:dd:d9:dd:c25:c25:d9be:eaa4
1662c19:dd:d9:dd:c25:c25:d9be:eaa5/1282c19:dd:d9:dd:c25:c25:d9be:eaa5
1672c19:dd:d9:dd:c25:c25:d9be:eaa6/1282c19:dd:d9:dd:c25:c25:d9be:eaa6
1682c19:dd:d9:dd:c25:c25:d9be:eaa7/1282c19:dd:d9:dd:c25:c25:d9be:eaa7
1692c19:dd:d9:dd:c25:c25:d9be:eaa8/1282c19:dd:d9:dd:c25:c25:d9be:eaa8
1702c19:dd:d9:dd:c25:c25:d9be:eaa9/1282c19:dd:d9:dd:c25:c25:d9be:eaa9
1712c19:dd:d9:dd:c25:c25:d9be:eaaa/1282c19:dd:d9:dd:c25:c25:d9be:eaaa
1722c19:dd:d9:dd:c25:c25:d9be:eaab/1282c19:dd:d9:dd:c25:c25:d9be:eaab
1732c19:dd:d9:dd:c25:c25:d9be:eaac/1282c19:dd:d9:dd:c25:c25:d9be:eaac
1742c19:dd:d9:dd:c25:c25:d9be:eaad/1282c19:dd:d9:dd:c25:c25:d9be:eaad
1752c19:dd:d9:dd:c25:c25:d9be:eaae/1282c19:dd:d9:dd:c25:c25:d9be:eaae
1762c19:dd:d9:dd:c25:c25:d9be:eaaf/1282c19:dd:d9:dd:c25:c25:d9be:eaaf
1772c19:dd:d9:dd:c25:c25:d9be:eab0/1282c19:dd:d9:dd:c25:c25:d9be:eab0
1782c19:dd:d9:dd:c25:c25:d9be:eab1/1282c19:dd:d9:dd:c25:c25:d9be:eab1
1792c19:dd:d9:dd:c25:c25:d9be:eab2/1282c19:dd:d9:dd:c25:c25:d9be:eab2
1802c19:dd:d9:dd:c25:c25:d9be:eab3/1282c19:dd:d9:dd:c25:c25:d9be:eab3
1812c19:dd:d9:dd:c25:c25:d9be:eab4/1282c19:dd:d9:dd:c25:c25:d9be:eab4
1822c19:dd:d9:dd:c25:c25:d9be:eab5/1282c19:dd:d9:dd:c25:c25:d9be:eab5
1832c19:dd:d9:dd:c25:c25:d9be:eab6/1282c19:dd:d9:dd:c25:c25:d9be:eab6
1842c19:dd:d9:dd:c25:c25:d9be:eab7/1282c19:dd:d9:dd:c25:c25:d9be:eab7
1852c19:dd:d9:dd:c25:c25:d9be:eab8/1282c19:dd:d9:dd:c25:c25:d9be:eab8
1862c19:dd:d9:dd:c25:c25:d9be:eab9/1282c19:dd:d9:dd:c25:c25:d9be:eab9
1872c19:dd:d9:dd:c25:c25:d9be:eaba/1282c19:dd:d9:dd:c25:c25:d9be:eaba
1882c19:dd:d9:dd:c25:c25:d9be:eabb/1282c19:dd:d9:dd:c25:c25:d9be:eabb
1892c19:dd:d9:dd:c25:c25:d9be:eabc/1282c19:dd:d9:dd:c25:c25:d9be:eabc
1902c19:dd:d9:dd:c25:c25:d9be:eabd/1282c19:dd:d9:dd:c25:c25:d9be:eabd
1912c19:dd:d9:dd:c25:c25:d9be:eabe/1282c19:dd:d9:dd:c25:c25:d9be:eabe
1922c19:dd:d9:dd:c25:c25:d9be:eabf/1282c19:dd:d9:dd:c25:c25:d9be:eabf
1932c19:dd:d9:dd:c25:c25:d9be:eac0/1282c19:dd:d9:dd:c25:c25:d9be:eac0
1942c19:dd:d9:dd:c25:c25:d9be:eac1/1282c19:dd:d9:dd:c25:c25:d9be:eac1
1952c19:dd:d9:dd:c25:c25:d9be:eac2/1282c19:dd:d9:dd:c25:c25:d9be:eac2
1962c19:dd:d9:dd:c25:c25:d9be:eac3/1282c19:dd:d9:dd:c25:c25:d9be:eac3
1972c19:dd:d9:dd:c25:c25:d9be:eac4/1282c19:dd:d9:dd:c25:c25:d9be:eac4
1982c19:dd:d9:dd:c25:c25:d9be:eac5/1282c19:dd:d9:dd:c25:c25:d9be:eac5
1992c19:dd:d9:dd:c25:c25:d9be:eac6/1282c19:dd:d9:dd:c25:c25:d9be:eac6
2002c19:dd:d9:dd:c25:c25:d9be:eac7/1282c19:dd:d9:dd:c25:c25:d9be:eac7
2012c19:dd:d9:dd:c25:c25:d9be:eac8/1282c19:dd:d9:dd:c25:c25:d9be:eac8
2022c19:dd:d9:dd:c25:c25:d9be:eac9/1282c19:dd:d9:dd:c25:c25:d9be:eac9
2032c19:dd:d9:dd:c25:c25:d9be:eaca/1282c19:dd:d9:dd:c25:c25:d9be:eaca
2042c19:dd:d9:dd:c25:c25:d9be:eacb/1282c19:dd:d9:dd:c25:c25:d9be:eacb
2052c19:dd:d9:dd:c25:c25:d9be:eacc/1282c19:dd:d9:dd:c25:c25:d9be:eacc
2062c19:dd:d9:dd:c25:c25:d9be:eacd/1282c19:dd:d9:dd:c25:c25:d9be:eacd
2072c19:dd:d9:dd:c25:c25:d9be:eace/1282c19:dd:d9:dd:c25:c25:d9be:eace
2082c19:dd:d9:dd:c25:c25:d9be:eacf/1282c19:dd:d9:dd:c25:c25:d9be:eacf
2092c19:dd:d9:dd:c25:c25:d9be:ead0/1282c19:dd:d9:dd:c25:c25:d9be:ead0
2102c19:dd:d9:dd:c25:c25:d9be:ead1/1282c19:dd:d9:dd:c25:c25:d9be:ead1
2112c19:dd:d9:dd:c25:c25:d9be:ead2/1282c19:dd:d9:dd:c25:c25:d9be:ead2
2122c19:dd:d9:dd:c25:c25:d9be:ead3/1282c19:dd:d9:dd:c25:c25:d9be:ead3
2132c19:dd:d9:dd:c25:c25:d9be:ead4/1282c19:dd:d9:dd:c25:c25:d9be:ead4
2142c19:dd:d9:dd:c25:c25:d9be:ead5/1282c19:dd:d9:dd:c25:c25:d9be:ead5
2152c19:dd:d9:dd:c25:c25:d9be:ead6/1282c19:dd:d9:dd:c25:c25:d9be:ead6
2162c19:dd:d9:dd:c25:c25:d9be:ead7/1282c19:dd:d9:dd:c25:c25:d9be:ead7
2172c19:dd:d9:dd:c25:c25:d9be:ead8/1282c19:dd:d9:dd:c25:c25:d9be:ead8
2182c19:dd:d9:dd:c25:c25:d9be:ead9/1282c19:dd:d9:dd:c25:c25:d9be:ead9
2192c19:dd:d9:dd:c25:c25:d9be:eada/1282c19:dd:d9:dd:c25:c25:d9be:eada
2202c19:dd:d9:dd:c25:c25:d9be:eadb/1282c19:dd:d9:dd:c25:c25:d9be:eadb
2212c19:dd:d9:dd:c25:c25:d9be:eadc/1282c19:dd:d9:dd:c25:c25:d9be:eadc
2222c19:dd:d9:dd:c25:c25:d9be:eadd/1282c19:dd:d9:dd:c25:c25:d9be:eadd
2232c19:dd:d9:dd:c25:c25:d9be:eade/1282c19:dd:d9:dd:c25:c25:d9be:eade
2242c19:dd:d9:dd:c25:c25:d9be:eadf/1282c19:dd:d9:dd:c25:c25:d9be:eadf
2252c19:dd:d9:dd:c25:c25:d9be:eae0/1282c19:dd:d9:dd:c25:c25:d9be:eae0
2262c19:dd:d9:dd:c25:c25:d9be:eae1/1282c19:dd:d9:dd:c25:c25:d9be:eae1
2272c19:dd:d9:dd:c25:c25:d9be:eae2/1282c19:dd:d9:dd:c25:c25:d9be:eae2
2282c19:dd:d9:dd:c25:c25:d9be:eae3/1282c19:dd:d9:dd:c25:c25:d9be:eae3
2292c19:dd:d9:dd:c25:c25:d9be:eae4/1282c19:dd:d9:dd:c25:c25:d9be:eae4
2302c19:dd:d9:dd:c25:c25:d9be:eae5/1282c19:dd:d9:dd:c25:c25:d9be:eae5
2312c19:dd:d9:dd:c25:c25:d9be:eae6/1282c19:dd:d9:dd:c25:c25:d9be:eae6
2322c19:dd:d9:dd:c25:c25:d9be:eae7/1282c19:dd:d9:dd:c25:c25:d9be:eae7
2332c19:dd:d9:dd:c25:c25:d9be:eae8/1282c19:dd:d9:dd:c25:c25:d9be:eae8
2342c19:dd:d9:dd:c25:c25:d9be:eae9/1282c19:dd:d9:dd:c25:c25:d9be:eae9
2352c19:dd:d9:dd:c25:c25:d9be:eaea/1282c19:dd:d9:dd:c25:c25:d9be:eaea
2362c19:dd:d9:dd:c25:c25:d9be:eaeb/1282c19:dd:d9:dd:c25:c25:d9be:eaeb
2372c19:dd:d9:dd:c25:c25:d9be:eaec/1282c19:dd:d9:dd:c25:c25:d9be:eaec
2382c19:dd:d9:dd:c25:c25:d9be:eaed/1282c19:dd:d9:dd:c25:c25:d9be:eaed
2392c19:dd:d9:dd:c25:c25:d9be:eaee/1282c19:dd:d9:dd:c25:c25:d9be:eaee
2402c19:dd:d9:dd:c25:c25:d9be:eaef/1282c19:dd:d9:dd:c25:c25:d9be:eaef
2412c19:dd:d9:dd:c25:c25:d9be:eaf0/1282c19:dd:d9:dd:c25:c25:d9be:eaf0
2422c19:dd:d9:dd:c25:c25:d9be:eaf1/1282c19:dd:d9:dd:c25:c25:d9be:eaf1
2432c19:dd:d9:dd:c25:c25:d9be:eaf2/1282c19:dd:d9:dd:c25:c25:d9be:eaf2
2442c19:dd:d9:dd:c25:c25:d9be:eaf3/1282c19:dd:d9:dd:c25:c25:d9be:eaf3
2452c19:dd:d9:dd:c25:c25:d9be:eaf4/1282c19:dd:d9:dd:c25:c25:d9be:eaf4
2462c19:dd:d9:dd:c25:c25:d9be:eaf5/1282c19:dd:d9:dd:c25:c25:d9be:eaf5
2472c19:dd:d9:dd:c25:c25:d9be:eaf6/1282c19:dd:d9:dd:c25:c25:d9be:eaf6
2482c19:dd:d9:dd:c25:c25:d9be:eaf7/1282c19:dd:d9:dd:c25:c25:d9be:eaf7
2492c19:dd:d9:dd:c25:c25:d9be:eaf8/1282c19:dd:d9:dd:c25:c25:d9be:eaf8
2502c19:dd:d9:dd:c25:c25:d9be:eaf9/1282c19:dd:d9:dd:c25:c25:d9be:eaf9
2512c19:dd:d9:dd:c25:c25:d9be:eafa/1282c19:dd:d9:dd:c25:c25:d9be:eafa
2522c19:dd:d9:dd:c25:c25:d9be:eafb/1282c19:dd:d9:dd:c25:c25:d9be:eafb
2532c19:dd:d9:dd:c25:c25:d9be:eafc/1282c19:dd:d9:dd:c25:c25:d9be:eafc
2542c19:dd:d9:dd:c25:c25:d9be:eafd/1282c19:dd:d9:dd:c25:c25:d9be:eafd
2552c19:dd:d9:dd:c25:c25:d9be:eafe/1282c19:dd:d9:dd:c25:c25:d9be:eafe
2562c19:dd:d9:dd:c25:c25:d9be:eaff/1282c19:dd:d9:dd:c25:c25:d9be:eaff

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.