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:c25b:d00a:df00/120
First address
2c19:dd:d9:dd:c25:c25b:d00a:df00
Last address
2c19:dd:d9:dd:c25:c25b:d00a:dfff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:c25b:d00a:df00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
f.d.a.0.0.d.b.5.2.c.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:c25b:d00a:df00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25b:d00a:df00/1282c19:dd:d9:dd:c25:c25b:d00a:df00
22c19:dd:d9:dd:c25:c25b:d00a:df01/1282c19:dd:d9:dd:c25:c25b:d00a:df01
32c19:dd:d9:dd:c25:c25b:d00a:df02/1282c19:dd:d9:dd:c25:c25b:d00a:df02
42c19:dd:d9:dd:c25:c25b:d00a:df03/1282c19:dd:d9:dd:c25:c25b:d00a:df03
52c19:dd:d9:dd:c25:c25b:d00a:df04/1282c19:dd:d9:dd:c25:c25b:d00a:df04
62c19:dd:d9:dd:c25:c25b:d00a:df05/1282c19:dd:d9:dd:c25:c25b:d00a:df05
72c19:dd:d9:dd:c25:c25b:d00a:df06/1282c19:dd:d9:dd:c25:c25b:d00a:df06
82c19:dd:d9:dd:c25:c25b:d00a:df07/1282c19:dd:d9:dd:c25:c25b:d00a:df07
92c19:dd:d9:dd:c25:c25b:d00a:df08/1282c19:dd:d9:dd:c25:c25b:d00a:df08
102c19:dd:d9:dd:c25:c25b:d00a:df09/1282c19:dd:d9:dd:c25:c25b:d00a:df09
112c19:dd:d9:dd:c25:c25b:d00a:df0a/1282c19:dd:d9:dd:c25:c25b:d00a:df0a
122c19:dd:d9:dd:c25:c25b:d00a:df0b/1282c19:dd:d9:dd:c25:c25b:d00a:df0b
132c19:dd:d9:dd:c25:c25b:d00a:df0c/1282c19:dd:d9:dd:c25:c25b:d00a:df0c
142c19:dd:d9:dd:c25:c25b:d00a:df0d/1282c19:dd:d9:dd:c25:c25b:d00a:df0d
152c19:dd:d9:dd:c25:c25b:d00a:df0e/1282c19:dd:d9:dd:c25:c25b:d00a:df0e
162c19:dd:d9:dd:c25:c25b:d00a:df0f/1282c19:dd:d9:dd:c25:c25b:d00a:df0f
172c19:dd:d9:dd:c25:c25b:d00a:df10/1282c19:dd:d9:dd:c25:c25b:d00a:df10
182c19:dd:d9:dd:c25:c25b:d00a:df11/1282c19:dd:d9:dd:c25:c25b:d00a:df11
192c19:dd:d9:dd:c25:c25b:d00a:df12/1282c19:dd:d9:dd:c25:c25b:d00a:df12
202c19:dd:d9:dd:c25:c25b:d00a:df13/1282c19:dd:d9:dd:c25:c25b:d00a:df13
212c19:dd:d9:dd:c25:c25b:d00a:df14/1282c19:dd:d9:dd:c25:c25b:d00a:df14
222c19:dd:d9:dd:c25:c25b:d00a:df15/1282c19:dd:d9:dd:c25:c25b:d00a:df15
232c19:dd:d9:dd:c25:c25b:d00a:df16/1282c19:dd:d9:dd:c25:c25b:d00a:df16
242c19:dd:d9:dd:c25:c25b:d00a:df17/1282c19:dd:d9:dd:c25:c25b:d00a:df17
252c19:dd:d9:dd:c25:c25b:d00a:df18/1282c19:dd:d9:dd:c25:c25b:d00a:df18
262c19:dd:d9:dd:c25:c25b:d00a:df19/1282c19:dd:d9:dd:c25:c25b:d00a:df19
272c19:dd:d9:dd:c25:c25b:d00a:df1a/1282c19:dd:d9:dd:c25:c25b:d00a:df1a
282c19:dd:d9:dd:c25:c25b:d00a:df1b/1282c19:dd:d9:dd:c25:c25b:d00a:df1b
292c19:dd:d9:dd:c25:c25b:d00a:df1c/1282c19:dd:d9:dd:c25:c25b:d00a:df1c
302c19:dd:d9:dd:c25:c25b:d00a:df1d/1282c19:dd:d9:dd:c25:c25b:d00a:df1d
312c19:dd:d9:dd:c25:c25b:d00a:df1e/1282c19:dd:d9:dd:c25:c25b:d00a:df1e
322c19:dd:d9:dd:c25:c25b:d00a:df1f/1282c19:dd:d9:dd:c25:c25b:d00a:df1f
332c19:dd:d9:dd:c25:c25b:d00a:df20/1282c19:dd:d9:dd:c25:c25b:d00a:df20
342c19:dd:d9:dd:c25:c25b:d00a:df21/1282c19:dd:d9:dd:c25:c25b:d00a:df21
352c19:dd:d9:dd:c25:c25b:d00a:df22/1282c19:dd:d9:dd:c25:c25b:d00a:df22
362c19:dd:d9:dd:c25:c25b:d00a:df23/1282c19:dd:d9:dd:c25:c25b:d00a:df23
372c19:dd:d9:dd:c25:c25b:d00a:df24/1282c19:dd:d9:dd:c25:c25b:d00a:df24
382c19:dd:d9:dd:c25:c25b:d00a:df25/1282c19:dd:d9:dd:c25:c25b:d00a:df25
392c19:dd:d9:dd:c25:c25b:d00a:df26/1282c19:dd:d9:dd:c25:c25b:d00a:df26
402c19:dd:d9:dd:c25:c25b:d00a:df27/1282c19:dd:d9:dd:c25:c25b:d00a:df27
412c19:dd:d9:dd:c25:c25b:d00a:df28/1282c19:dd:d9:dd:c25:c25b:d00a:df28
422c19:dd:d9:dd:c25:c25b:d00a:df29/1282c19:dd:d9:dd:c25:c25b:d00a:df29
432c19:dd:d9:dd:c25:c25b:d00a:df2a/1282c19:dd:d9:dd:c25:c25b:d00a:df2a
442c19:dd:d9:dd:c25:c25b:d00a:df2b/1282c19:dd:d9:dd:c25:c25b:d00a:df2b
452c19:dd:d9:dd:c25:c25b:d00a:df2c/1282c19:dd:d9:dd:c25:c25b:d00a:df2c
462c19:dd:d9:dd:c25:c25b:d00a:df2d/1282c19:dd:d9:dd:c25:c25b:d00a:df2d
472c19:dd:d9:dd:c25:c25b:d00a:df2e/1282c19:dd:d9:dd:c25:c25b:d00a:df2e
482c19:dd:d9:dd:c25:c25b:d00a:df2f/1282c19:dd:d9:dd:c25:c25b:d00a:df2f
492c19:dd:d9:dd:c25:c25b:d00a:df30/1282c19:dd:d9:dd:c25:c25b:d00a:df30
502c19:dd:d9:dd:c25:c25b:d00a:df31/1282c19:dd:d9:dd:c25:c25b:d00a:df31
512c19:dd:d9:dd:c25:c25b:d00a:df32/1282c19:dd:d9:dd:c25:c25b:d00a:df32
522c19:dd:d9:dd:c25:c25b:d00a:df33/1282c19:dd:d9:dd:c25:c25b:d00a:df33
532c19:dd:d9:dd:c25:c25b:d00a:df34/1282c19:dd:d9:dd:c25:c25b:d00a:df34
542c19:dd:d9:dd:c25:c25b:d00a:df35/1282c19:dd:d9:dd:c25:c25b:d00a:df35
552c19:dd:d9:dd:c25:c25b:d00a:df36/1282c19:dd:d9:dd:c25:c25b:d00a:df36
562c19:dd:d9:dd:c25:c25b:d00a:df37/1282c19:dd:d9:dd:c25:c25b:d00a:df37
572c19:dd:d9:dd:c25:c25b:d00a:df38/1282c19:dd:d9:dd:c25:c25b:d00a:df38
582c19:dd:d9:dd:c25:c25b:d00a:df39/1282c19:dd:d9:dd:c25:c25b:d00a:df39
592c19:dd:d9:dd:c25:c25b:d00a:df3a/1282c19:dd:d9:dd:c25:c25b:d00a:df3a
602c19:dd:d9:dd:c25:c25b:d00a:df3b/1282c19:dd:d9:dd:c25:c25b:d00a:df3b
612c19:dd:d9:dd:c25:c25b:d00a:df3c/1282c19:dd:d9:dd:c25:c25b:d00a:df3c
622c19:dd:d9:dd:c25:c25b:d00a:df3d/1282c19:dd:d9:dd:c25:c25b:d00a:df3d
632c19:dd:d9:dd:c25:c25b:d00a:df3e/1282c19:dd:d9:dd:c25:c25b:d00a:df3e
642c19:dd:d9:dd:c25:c25b:d00a:df3f/1282c19:dd:d9:dd:c25:c25b:d00a:df3f
652c19:dd:d9:dd:c25:c25b:d00a:df40/1282c19:dd:d9:dd:c25:c25b:d00a:df40
662c19:dd:d9:dd:c25:c25b:d00a:df41/1282c19:dd:d9:dd:c25:c25b:d00a:df41
672c19:dd:d9:dd:c25:c25b:d00a:df42/1282c19:dd:d9:dd:c25:c25b:d00a:df42
682c19:dd:d9:dd:c25:c25b:d00a:df43/1282c19:dd:d9:dd:c25:c25b:d00a:df43
692c19:dd:d9:dd:c25:c25b:d00a:df44/1282c19:dd:d9:dd:c25:c25b:d00a:df44
702c19:dd:d9:dd:c25:c25b:d00a:df45/1282c19:dd:d9:dd:c25:c25b:d00a:df45
712c19:dd:d9:dd:c25:c25b:d00a:df46/1282c19:dd:d9:dd:c25:c25b:d00a:df46
722c19:dd:d9:dd:c25:c25b:d00a:df47/1282c19:dd:d9:dd:c25:c25b:d00a:df47
732c19:dd:d9:dd:c25:c25b:d00a:df48/1282c19:dd:d9:dd:c25:c25b:d00a:df48
742c19:dd:d9:dd:c25:c25b:d00a:df49/1282c19:dd:d9:dd:c25:c25b:d00a:df49
752c19:dd:d9:dd:c25:c25b:d00a:df4a/1282c19:dd:d9:dd:c25:c25b:d00a:df4a
762c19:dd:d9:dd:c25:c25b:d00a:df4b/1282c19:dd:d9:dd:c25:c25b:d00a:df4b
772c19:dd:d9:dd:c25:c25b:d00a:df4c/1282c19:dd:d9:dd:c25:c25b:d00a:df4c
782c19:dd:d9:dd:c25:c25b:d00a:df4d/1282c19:dd:d9:dd:c25:c25b:d00a:df4d
792c19:dd:d9:dd:c25:c25b:d00a:df4e/1282c19:dd:d9:dd:c25:c25b:d00a:df4e
802c19:dd:d9:dd:c25:c25b:d00a:df4f/1282c19:dd:d9:dd:c25:c25b:d00a:df4f
812c19:dd:d9:dd:c25:c25b:d00a:df50/1282c19:dd:d9:dd:c25:c25b:d00a:df50
822c19:dd:d9:dd:c25:c25b:d00a:df51/1282c19:dd:d9:dd:c25:c25b:d00a:df51
832c19:dd:d9:dd:c25:c25b:d00a:df52/1282c19:dd:d9:dd:c25:c25b:d00a:df52
842c19:dd:d9:dd:c25:c25b:d00a:df53/1282c19:dd:d9:dd:c25:c25b:d00a:df53
852c19:dd:d9:dd:c25:c25b:d00a:df54/1282c19:dd:d9:dd:c25:c25b:d00a:df54
862c19:dd:d9:dd:c25:c25b:d00a:df55/1282c19:dd:d9:dd:c25:c25b:d00a:df55
872c19:dd:d9:dd:c25:c25b:d00a:df56/1282c19:dd:d9:dd:c25:c25b:d00a:df56
882c19:dd:d9:dd:c25:c25b:d00a:df57/1282c19:dd:d9:dd:c25:c25b:d00a:df57
892c19:dd:d9:dd:c25:c25b:d00a:df58/1282c19:dd:d9:dd:c25:c25b:d00a:df58
902c19:dd:d9:dd:c25:c25b:d00a:df59/1282c19:dd:d9:dd:c25:c25b:d00a:df59
912c19:dd:d9:dd:c25:c25b:d00a:df5a/1282c19:dd:d9:dd:c25:c25b:d00a:df5a
922c19:dd:d9:dd:c25:c25b:d00a:df5b/1282c19:dd:d9:dd:c25:c25b:d00a:df5b
932c19:dd:d9:dd:c25:c25b:d00a:df5c/1282c19:dd:d9:dd:c25:c25b:d00a:df5c
942c19:dd:d9:dd:c25:c25b:d00a:df5d/1282c19:dd:d9:dd:c25:c25b:d00a:df5d
952c19:dd:d9:dd:c25:c25b:d00a:df5e/1282c19:dd:d9:dd:c25:c25b:d00a:df5e
962c19:dd:d9:dd:c25:c25b:d00a:df5f/1282c19:dd:d9:dd:c25:c25b:d00a:df5f
972c19:dd:d9:dd:c25:c25b:d00a:df60/1282c19:dd:d9:dd:c25:c25b:d00a:df60
982c19:dd:d9:dd:c25:c25b:d00a:df61/1282c19:dd:d9:dd:c25:c25b:d00a:df61
992c19:dd:d9:dd:c25:c25b:d00a:df62/1282c19:dd:d9:dd:c25:c25b:d00a:df62
1002c19:dd:d9:dd:c25:c25b:d00a:df63/1282c19:dd:d9:dd:c25:c25b:d00a:df63
1012c19:dd:d9:dd:c25:c25b:d00a:df64/1282c19:dd:d9:dd:c25:c25b:d00a:df64
1022c19:dd:d9:dd:c25:c25b:d00a:df65/1282c19:dd:d9:dd:c25:c25b:d00a:df65
1032c19:dd:d9:dd:c25:c25b:d00a:df66/1282c19:dd:d9:dd:c25:c25b:d00a:df66
1042c19:dd:d9:dd:c25:c25b:d00a:df67/1282c19:dd:d9:dd:c25:c25b:d00a:df67
1052c19:dd:d9:dd:c25:c25b:d00a:df68/1282c19:dd:d9:dd:c25:c25b:d00a:df68
1062c19:dd:d9:dd:c25:c25b:d00a:df69/1282c19:dd:d9:dd:c25:c25b:d00a:df69
1072c19:dd:d9:dd:c25:c25b:d00a:df6a/1282c19:dd:d9:dd:c25:c25b:d00a:df6a
1082c19:dd:d9:dd:c25:c25b:d00a:df6b/1282c19:dd:d9:dd:c25:c25b:d00a:df6b
1092c19:dd:d9:dd:c25:c25b:d00a:df6c/1282c19:dd:d9:dd:c25:c25b:d00a:df6c
1102c19:dd:d9:dd:c25:c25b:d00a:df6d/1282c19:dd:d9:dd:c25:c25b:d00a:df6d
1112c19:dd:d9:dd:c25:c25b:d00a:df6e/1282c19:dd:d9:dd:c25:c25b:d00a:df6e
1122c19:dd:d9:dd:c25:c25b:d00a:df6f/1282c19:dd:d9:dd:c25:c25b:d00a:df6f
1132c19:dd:d9:dd:c25:c25b:d00a:df70/1282c19:dd:d9:dd:c25:c25b:d00a:df70
1142c19:dd:d9:dd:c25:c25b:d00a:df71/1282c19:dd:d9:dd:c25:c25b:d00a:df71
1152c19:dd:d9:dd:c25:c25b:d00a:df72/1282c19:dd:d9:dd:c25:c25b:d00a:df72
1162c19:dd:d9:dd:c25:c25b:d00a:df73/1282c19:dd:d9:dd:c25:c25b:d00a:df73
1172c19:dd:d9:dd:c25:c25b:d00a:df74/1282c19:dd:d9:dd:c25:c25b:d00a:df74
1182c19:dd:d9:dd:c25:c25b:d00a:df75/1282c19:dd:d9:dd:c25:c25b:d00a:df75
1192c19:dd:d9:dd:c25:c25b:d00a:df76/1282c19:dd:d9:dd:c25:c25b:d00a:df76
1202c19:dd:d9:dd:c25:c25b:d00a:df77/1282c19:dd:d9:dd:c25:c25b:d00a:df77
1212c19:dd:d9:dd:c25:c25b:d00a:df78/1282c19:dd:d9:dd:c25:c25b:d00a:df78
1222c19:dd:d9:dd:c25:c25b:d00a:df79/1282c19:dd:d9:dd:c25:c25b:d00a:df79
1232c19:dd:d9:dd:c25:c25b:d00a:df7a/1282c19:dd:d9:dd:c25:c25b:d00a:df7a
1242c19:dd:d9:dd:c25:c25b:d00a:df7b/1282c19:dd:d9:dd:c25:c25b:d00a:df7b
1252c19:dd:d9:dd:c25:c25b:d00a:df7c/1282c19:dd:d9:dd:c25:c25b:d00a:df7c
1262c19:dd:d9:dd:c25:c25b:d00a:df7d/1282c19:dd:d9:dd:c25:c25b:d00a:df7d
1272c19:dd:d9:dd:c25:c25b:d00a:df7e/1282c19:dd:d9:dd:c25:c25b:d00a:df7e
1282c19:dd:d9:dd:c25:c25b:d00a:df7f/1282c19:dd:d9:dd:c25:c25b:d00a:df7f
1292c19:dd:d9:dd:c25:c25b:d00a:df80/1282c19:dd:d9:dd:c25:c25b:d00a:df80
1302c19:dd:d9:dd:c25:c25b:d00a:df81/1282c19:dd:d9:dd:c25:c25b:d00a:df81
1312c19:dd:d9:dd:c25:c25b:d00a:df82/1282c19:dd:d9:dd:c25:c25b:d00a:df82
1322c19:dd:d9:dd:c25:c25b:d00a:df83/1282c19:dd:d9:dd:c25:c25b:d00a:df83
1332c19:dd:d9:dd:c25:c25b:d00a:df84/1282c19:dd:d9:dd:c25:c25b:d00a:df84
1342c19:dd:d9:dd:c25:c25b:d00a:df85/1282c19:dd:d9:dd:c25:c25b:d00a:df85
1352c19:dd:d9:dd:c25:c25b:d00a:df86/1282c19:dd:d9:dd:c25:c25b:d00a:df86
1362c19:dd:d9:dd:c25:c25b:d00a:df87/1282c19:dd:d9:dd:c25:c25b:d00a:df87
1372c19:dd:d9:dd:c25:c25b:d00a:df88/1282c19:dd:d9:dd:c25:c25b:d00a:df88
1382c19:dd:d9:dd:c25:c25b:d00a:df89/1282c19:dd:d9:dd:c25:c25b:d00a:df89
1392c19:dd:d9:dd:c25:c25b:d00a:df8a/1282c19:dd:d9:dd:c25:c25b:d00a:df8a
1402c19:dd:d9:dd:c25:c25b:d00a:df8b/1282c19:dd:d9:dd:c25:c25b:d00a:df8b
1412c19:dd:d9:dd:c25:c25b:d00a:df8c/1282c19:dd:d9:dd:c25:c25b:d00a:df8c
1422c19:dd:d9:dd:c25:c25b:d00a:df8d/1282c19:dd:d9:dd:c25:c25b:d00a:df8d
1432c19:dd:d9:dd:c25:c25b:d00a:df8e/1282c19:dd:d9:dd:c25:c25b:d00a:df8e
1442c19:dd:d9:dd:c25:c25b:d00a:df8f/1282c19:dd:d9:dd:c25:c25b:d00a:df8f
1452c19:dd:d9:dd:c25:c25b:d00a:df90/1282c19:dd:d9:dd:c25:c25b:d00a:df90
1462c19:dd:d9:dd:c25:c25b:d00a:df91/1282c19:dd:d9:dd:c25:c25b:d00a:df91
1472c19:dd:d9:dd:c25:c25b:d00a:df92/1282c19:dd:d9:dd:c25:c25b:d00a:df92
1482c19:dd:d9:dd:c25:c25b:d00a:df93/1282c19:dd:d9:dd:c25:c25b:d00a:df93
1492c19:dd:d9:dd:c25:c25b:d00a:df94/1282c19:dd:d9:dd:c25:c25b:d00a:df94
1502c19:dd:d9:dd:c25:c25b:d00a:df95/1282c19:dd:d9:dd:c25:c25b:d00a:df95
1512c19:dd:d9:dd:c25:c25b:d00a:df96/1282c19:dd:d9:dd:c25:c25b:d00a:df96
1522c19:dd:d9:dd:c25:c25b:d00a:df97/1282c19:dd:d9:dd:c25:c25b:d00a:df97
1532c19:dd:d9:dd:c25:c25b:d00a:df98/1282c19:dd:d9:dd:c25:c25b:d00a:df98
1542c19:dd:d9:dd:c25:c25b:d00a:df99/1282c19:dd:d9:dd:c25:c25b:d00a:df99
1552c19:dd:d9:dd:c25:c25b:d00a:df9a/1282c19:dd:d9:dd:c25:c25b:d00a:df9a
1562c19:dd:d9:dd:c25:c25b:d00a:df9b/1282c19:dd:d9:dd:c25:c25b:d00a:df9b
1572c19:dd:d9:dd:c25:c25b:d00a:df9c/1282c19:dd:d9:dd:c25:c25b:d00a:df9c
1582c19:dd:d9:dd:c25:c25b:d00a:df9d/1282c19:dd:d9:dd:c25:c25b:d00a:df9d
1592c19:dd:d9:dd:c25:c25b:d00a:df9e/1282c19:dd:d9:dd:c25:c25b:d00a:df9e
1602c19:dd:d9:dd:c25:c25b:d00a:df9f/1282c19:dd:d9:dd:c25:c25b:d00a:df9f
1612c19:dd:d9:dd:c25:c25b:d00a:dfa0/1282c19:dd:d9:dd:c25:c25b:d00a:dfa0
1622c19:dd:d9:dd:c25:c25b:d00a:dfa1/1282c19:dd:d9:dd:c25:c25b:d00a:dfa1
1632c19:dd:d9:dd:c25:c25b:d00a:dfa2/1282c19:dd:d9:dd:c25:c25b:d00a:dfa2
1642c19:dd:d9:dd:c25:c25b:d00a:dfa3/1282c19:dd:d9:dd:c25:c25b:d00a:dfa3
1652c19:dd:d9:dd:c25:c25b:d00a:dfa4/1282c19:dd:d9:dd:c25:c25b:d00a:dfa4
1662c19:dd:d9:dd:c25:c25b:d00a:dfa5/1282c19:dd:d9:dd:c25:c25b:d00a:dfa5
1672c19:dd:d9:dd:c25:c25b:d00a:dfa6/1282c19:dd:d9:dd:c25:c25b:d00a:dfa6
1682c19:dd:d9:dd:c25:c25b:d00a:dfa7/1282c19:dd:d9:dd:c25:c25b:d00a:dfa7
1692c19:dd:d9:dd:c25:c25b:d00a:dfa8/1282c19:dd:d9:dd:c25:c25b:d00a:dfa8
1702c19:dd:d9:dd:c25:c25b:d00a:dfa9/1282c19:dd:d9:dd:c25:c25b:d00a:dfa9
1712c19:dd:d9:dd:c25:c25b:d00a:dfaa/1282c19:dd:d9:dd:c25:c25b:d00a:dfaa
1722c19:dd:d9:dd:c25:c25b:d00a:dfab/1282c19:dd:d9:dd:c25:c25b:d00a:dfab
1732c19:dd:d9:dd:c25:c25b:d00a:dfac/1282c19:dd:d9:dd:c25:c25b:d00a:dfac
1742c19:dd:d9:dd:c25:c25b:d00a:dfad/1282c19:dd:d9:dd:c25:c25b:d00a:dfad
1752c19:dd:d9:dd:c25:c25b:d00a:dfae/1282c19:dd:d9:dd:c25:c25b:d00a:dfae
1762c19:dd:d9:dd:c25:c25b:d00a:dfaf/1282c19:dd:d9:dd:c25:c25b:d00a:dfaf
1772c19:dd:d9:dd:c25:c25b:d00a:dfb0/1282c19:dd:d9:dd:c25:c25b:d00a:dfb0
1782c19:dd:d9:dd:c25:c25b:d00a:dfb1/1282c19:dd:d9:dd:c25:c25b:d00a:dfb1
1792c19:dd:d9:dd:c25:c25b:d00a:dfb2/1282c19:dd:d9:dd:c25:c25b:d00a:dfb2
1802c19:dd:d9:dd:c25:c25b:d00a:dfb3/1282c19:dd:d9:dd:c25:c25b:d00a:dfb3
1812c19:dd:d9:dd:c25:c25b:d00a:dfb4/1282c19:dd:d9:dd:c25:c25b:d00a:dfb4
1822c19:dd:d9:dd:c25:c25b:d00a:dfb5/1282c19:dd:d9:dd:c25:c25b:d00a:dfb5
1832c19:dd:d9:dd:c25:c25b:d00a:dfb6/1282c19:dd:d9:dd:c25:c25b:d00a:dfb6
1842c19:dd:d9:dd:c25:c25b:d00a:dfb7/1282c19:dd:d9:dd:c25:c25b:d00a:dfb7
1852c19:dd:d9:dd:c25:c25b:d00a:dfb8/1282c19:dd:d9:dd:c25:c25b:d00a:dfb8
1862c19:dd:d9:dd:c25:c25b:d00a:dfb9/1282c19:dd:d9:dd:c25:c25b:d00a:dfb9
1872c19:dd:d9:dd:c25:c25b:d00a:dfba/1282c19:dd:d9:dd:c25:c25b:d00a:dfba
1882c19:dd:d9:dd:c25:c25b:d00a:dfbb/1282c19:dd:d9:dd:c25:c25b:d00a:dfbb
1892c19:dd:d9:dd:c25:c25b:d00a:dfbc/1282c19:dd:d9:dd:c25:c25b:d00a:dfbc
1902c19:dd:d9:dd:c25:c25b:d00a:dfbd/1282c19:dd:d9:dd:c25:c25b:d00a:dfbd
1912c19:dd:d9:dd:c25:c25b:d00a:dfbe/1282c19:dd:d9:dd:c25:c25b:d00a:dfbe
1922c19:dd:d9:dd:c25:c25b:d00a:dfbf/1282c19:dd:d9:dd:c25:c25b:d00a:dfbf
1932c19:dd:d9:dd:c25:c25b:d00a:dfc0/1282c19:dd:d9:dd:c25:c25b:d00a:dfc0
1942c19:dd:d9:dd:c25:c25b:d00a:dfc1/1282c19:dd:d9:dd:c25:c25b:d00a:dfc1
1952c19:dd:d9:dd:c25:c25b:d00a:dfc2/1282c19:dd:d9:dd:c25:c25b:d00a:dfc2
1962c19:dd:d9:dd:c25:c25b:d00a:dfc3/1282c19:dd:d9:dd:c25:c25b:d00a:dfc3
1972c19:dd:d9:dd:c25:c25b:d00a:dfc4/1282c19:dd:d9:dd:c25:c25b:d00a:dfc4
1982c19:dd:d9:dd:c25:c25b:d00a:dfc5/1282c19:dd:d9:dd:c25:c25b:d00a:dfc5
1992c19:dd:d9:dd:c25:c25b:d00a:dfc6/1282c19:dd:d9:dd:c25:c25b:d00a:dfc6
2002c19:dd:d9:dd:c25:c25b:d00a:dfc7/1282c19:dd:d9:dd:c25:c25b:d00a:dfc7
2012c19:dd:d9:dd:c25:c25b:d00a:dfc8/1282c19:dd:d9:dd:c25:c25b:d00a:dfc8
2022c19:dd:d9:dd:c25:c25b:d00a:dfc9/1282c19:dd:d9:dd:c25:c25b:d00a:dfc9
2032c19:dd:d9:dd:c25:c25b:d00a:dfca/1282c19:dd:d9:dd:c25:c25b:d00a:dfca
2042c19:dd:d9:dd:c25:c25b:d00a:dfcb/1282c19:dd:d9:dd:c25:c25b:d00a:dfcb
2052c19:dd:d9:dd:c25:c25b:d00a:dfcc/1282c19:dd:d9:dd:c25:c25b:d00a:dfcc
2062c19:dd:d9:dd:c25:c25b:d00a:dfcd/1282c19:dd:d9:dd:c25:c25b:d00a:dfcd
2072c19:dd:d9:dd:c25:c25b:d00a:dfce/1282c19:dd:d9:dd:c25:c25b:d00a:dfce
2082c19:dd:d9:dd:c25:c25b:d00a:dfcf/1282c19:dd:d9:dd:c25:c25b:d00a:dfcf
2092c19:dd:d9:dd:c25:c25b:d00a:dfd0/1282c19:dd:d9:dd:c25:c25b:d00a:dfd0
2102c19:dd:d9:dd:c25:c25b:d00a:dfd1/1282c19:dd:d9:dd:c25:c25b:d00a:dfd1
2112c19:dd:d9:dd:c25:c25b:d00a:dfd2/1282c19:dd:d9:dd:c25:c25b:d00a:dfd2
2122c19:dd:d9:dd:c25:c25b:d00a:dfd3/1282c19:dd:d9:dd:c25:c25b:d00a:dfd3
2132c19:dd:d9:dd:c25:c25b:d00a:dfd4/1282c19:dd:d9:dd:c25:c25b:d00a:dfd4
2142c19:dd:d9:dd:c25:c25b:d00a:dfd5/1282c19:dd:d9:dd:c25:c25b:d00a:dfd5
2152c19:dd:d9:dd:c25:c25b:d00a:dfd6/1282c19:dd:d9:dd:c25:c25b:d00a:dfd6
2162c19:dd:d9:dd:c25:c25b:d00a:dfd7/1282c19:dd:d9:dd:c25:c25b:d00a:dfd7
2172c19:dd:d9:dd:c25:c25b:d00a:dfd8/1282c19:dd:d9:dd:c25:c25b:d00a:dfd8
2182c19:dd:d9:dd:c25:c25b:d00a:dfd9/1282c19:dd:d9:dd:c25:c25b:d00a:dfd9
2192c19:dd:d9:dd:c25:c25b:d00a:dfda/1282c19:dd:d9:dd:c25:c25b:d00a:dfda
2202c19:dd:d9:dd:c25:c25b:d00a:dfdb/1282c19:dd:d9:dd:c25:c25b:d00a:dfdb
2212c19:dd:d9:dd:c25:c25b:d00a:dfdc/1282c19:dd:d9:dd:c25:c25b:d00a:dfdc
2222c19:dd:d9:dd:c25:c25b:d00a:dfdd/1282c19:dd:d9:dd:c25:c25b:d00a:dfdd
2232c19:dd:d9:dd:c25:c25b:d00a:dfde/1282c19:dd:d9:dd:c25:c25b:d00a:dfde
2242c19:dd:d9:dd:c25:c25b:d00a:dfdf/1282c19:dd:d9:dd:c25:c25b:d00a:dfdf
2252c19:dd:d9:dd:c25:c25b:d00a:dfe0/1282c19:dd:d9:dd:c25:c25b:d00a:dfe0
2262c19:dd:d9:dd:c25:c25b:d00a:dfe1/1282c19:dd:d9:dd:c25:c25b:d00a:dfe1
2272c19:dd:d9:dd:c25:c25b:d00a:dfe2/1282c19:dd:d9:dd:c25:c25b:d00a:dfe2
2282c19:dd:d9:dd:c25:c25b:d00a:dfe3/1282c19:dd:d9:dd:c25:c25b:d00a:dfe3
2292c19:dd:d9:dd:c25:c25b:d00a:dfe4/1282c19:dd:d9:dd:c25:c25b:d00a:dfe4
2302c19:dd:d9:dd:c25:c25b:d00a:dfe5/1282c19:dd:d9:dd:c25:c25b:d00a:dfe5
2312c19:dd:d9:dd:c25:c25b:d00a:dfe6/1282c19:dd:d9:dd:c25:c25b:d00a:dfe6
2322c19:dd:d9:dd:c25:c25b:d00a:dfe7/1282c19:dd:d9:dd:c25:c25b:d00a:dfe7
2332c19:dd:d9:dd:c25:c25b:d00a:dfe8/1282c19:dd:d9:dd:c25:c25b:d00a:dfe8
2342c19:dd:d9:dd:c25:c25b:d00a:dfe9/1282c19:dd:d9:dd:c25:c25b:d00a:dfe9
2352c19:dd:d9:dd:c25:c25b:d00a:dfea/1282c19:dd:d9:dd:c25:c25b:d00a:dfea
2362c19:dd:d9:dd:c25:c25b:d00a:dfeb/1282c19:dd:d9:dd:c25:c25b:d00a:dfeb
2372c19:dd:d9:dd:c25:c25b:d00a:dfec/1282c19:dd:d9:dd:c25:c25b:d00a:dfec
2382c19:dd:d9:dd:c25:c25b:d00a:dfed/1282c19:dd:d9:dd:c25:c25b:d00a:dfed
2392c19:dd:d9:dd:c25:c25b:d00a:dfee/1282c19:dd:d9:dd:c25:c25b:d00a:dfee
2402c19:dd:d9:dd:c25:c25b:d00a:dfef/1282c19:dd:d9:dd:c25:c25b:d00a:dfef
2412c19:dd:d9:dd:c25:c25b:d00a:dff0/1282c19:dd:d9:dd:c25:c25b:d00a:dff0
2422c19:dd:d9:dd:c25:c25b:d00a:dff1/1282c19:dd:d9:dd:c25:c25b:d00a:dff1
2432c19:dd:d9:dd:c25:c25b:d00a:dff2/1282c19:dd:d9:dd:c25:c25b:d00a:dff2
2442c19:dd:d9:dd:c25:c25b:d00a:dff3/1282c19:dd:d9:dd:c25:c25b:d00a:dff3
2452c19:dd:d9:dd:c25:c25b:d00a:dff4/1282c19:dd:d9:dd:c25:c25b:d00a:dff4
2462c19:dd:d9:dd:c25:c25b:d00a:dff5/1282c19:dd:d9:dd:c25:c25b:d00a:dff5
2472c19:dd:d9:dd:c25:c25b:d00a:dff6/1282c19:dd:d9:dd:c25:c25b:d00a:dff6
2482c19:dd:d9:dd:c25:c25b:d00a:dff7/1282c19:dd:d9:dd:c25:c25b:d00a:dff7
2492c19:dd:d9:dd:c25:c25b:d00a:dff8/1282c19:dd:d9:dd:c25:c25b:d00a:dff8
2502c19:dd:d9:dd:c25:c25b:d00a:dff9/1282c19:dd:d9:dd:c25:c25b:d00a:dff9
2512c19:dd:d9:dd:c25:c25b:d00a:dffa/1282c19:dd:d9:dd:c25:c25b:d00a:dffa
2522c19:dd:d9:dd:c25:c25b:d00a:dffb/1282c19:dd:d9:dd:c25:c25b:d00a:dffb
2532c19:dd:d9:dd:c25:c25b:d00a:dffc/1282c19:dd:d9:dd:c25:c25b:d00a:dffc
2542c19:dd:d9:dd:c25:c25b:d00a:dffd/1282c19:dd:d9:dd:c25:c25b:d00a:dffd
2552c19:dd:d9:dd:c25:c25b:d00a:dffe/1282c19:dd:d9:dd:c25:c25b:d00a:dffe
2562c19:dd:d9:dd:c25:c25b:d00a:dfff/1282c19:dd:d9:dd:c25:c25b:d00a:dfff

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.