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:dc00/120
First address
2c19:dd:d9:dd:c25:c25b:d00a:dc00
Last address
2c19:dd:d9:dd:c25:c25b:d00a:dcff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:c25b:d00a:dc00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
c.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:dc00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25b:d00a:dc00/1282c19:dd:d9:dd:c25:c25b:d00a:dc00
22c19:dd:d9:dd:c25:c25b:d00a:dc01/1282c19:dd:d9:dd:c25:c25b:d00a:dc01
32c19:dd:d9:dd:c25:c25b:d00a:dc02/1282c19:dd:d9:dd:c25:c25b:d00a:dc02
42c19:dd:d9:dd:c25:c25b:d00a:dc03/1282c19:dd:d9:dd:c25:c25b:d00a:dc03
52c19:dd:d9:dd:c25:c25b:d00a:dc04/1282c19:dd:d9:dd:c25:c25b:d00a:dc04
62c19:dd:d9:dd:c25:c25b:d00a:dc05/1282c19:dd:d9:dd:c25:c25b:d00a:dc05
72c19:dd:d9:dd:c25:c25b:d00a:dc06/1282c19:dd:d9:dd:c25:c25b:d00a:dc06
82c19:dd:d9:dd:c25:c25b:d00a:dc07/1282c19:dd:d9:dd:c25:c25b:d00a:dc07
92c19:dd:d9:dd:c25:c25b:d00a:dc08/1282c19:dd:d9:dd:c25:c25b:d00a:dc08
102c19:dd:d9:dd:c25:c25b:d00a:dc09/1282c19:dd:d9:dd:c25:c25b:d00a:dc09
112c19:dd:d9:dd:c25:c25b:d00a:dc0a/1282c19:dd:d9:dd:c25:c25b:d00a:dc0a
122c19:dd:d9:dd:c25:c25b:d00a:dc0b/1282c19:dd:d9:dd:c25:c25b:d00a:dc0b
132c19:dd:d9:dd:c25:c25b:d00a:dc0c/1282c19:dd:d9:dd:c25:c25b:d00a:dc0c
142c19:dd:d9:dd:c25:c25b:d00a:dc0d/1282c19:dd:d9:dd:c25:c25b:d00a:dc0d
152c19:dd:d9:dd:c25:c25b:d00a:dc0e/1282c19:dd:d9:dd:c25:c25b:d00a:dc0e
162c19:dd:d9:dd:c25:c25b:d00a:dc0f/1282c19:dd:d9:dd:c25:c25b:d00a:dc0f
172c19:dd:d9:dd:c25:c25b:d00a:dc10/1282c19:dd:d9:dd:c25:c25b:d00a:dc10
182c19:dd:d9:dd:c25:c25b:d00a:dc11/1282c19:dd:d9:dd:c25:c25b:d00a:dc11
192c19:dd:d9:dd:c25:c25b:d00a:dc12/1282c19:dd:d9:dd:c25:c25b:d00a:dc12
202c19:dd:d9:dd:c25:c25b:d00a:dc13/1282c19:dd:d9:dd:c25:c25b:d00a:dc13
212c19:dd:d9:dd:c25:c25b:d00a:dc14/1282c19:dd:d9:dd:c25:c25b:d00a:dc14
222c19:dd:d9:dd:c25:c25b:d00a:dc15/1282c19:dd:d9:dd:c25:c25b:d00a:dc15
232c19:dd:d9:dd:c25:c25b:d00a:dc16/1282c19:dd:d9:dd:c25:c25b:d00a:dc16
242c19:dd:d9:dd:c25:c25b:d00a:dc17/1282c19:dd:d9:dd:c25:c25b:d00a:dc17
252c19:dd:d9:dd:c25:c25b:d00a:dc18/1282c19:dd:d9:dd:c25:c25b:d00a:dc18
262c19:dd:d9:dd:c25:c25b:d00a:dc19/1282c19:dd:d9:dd:c25:c25b:d00a:dc19
272c19:dd:d9:dd:c25:c25b:d00a:dc1a/1282c19:dd:d9:dd:c25:c25b:d00a:dc1a
282c19:dd:d9:dd:c25:c25b:d00a:dc1b/1282c19:dd:d9:dd:c25:c25b:d00a:dc1b
292c19:dd:d9:dd:c25:c25b:d00a:dc1c/1282c19:dd:d9:dd:c25:c25b:d00a:dc1c
302c19:dd:d9:dd:c25:c25b:d00a:dc1d/1282c19:dd:d9:dd:c25:c25b:d00a:dc1d
312c19:dd:d9:dd:c25:c25b:d00a:dc1e/1282c19:dd:d9:dd:c25:c25b:d00a:dc1e
322c19:dd:d9:dd:c25:c25b:d00a:dc1f/1282c19:dd:d9:dd:c25:c25b:d00a:dc1f
332c19:dd:d9:dd:c25:c25b:d00a:dc20/1282c19:dd:d9:dd:c25:c25b:d00a:dc20
342c19:dd:d9:dd:c25:c25b:d00a:dc21/1282c19:dd:d9:dd:c25:c25b:d00a:dc21
352c19:dd:d9:dd:c25:c25b:d00a:dc22/1282c19:dd:d9:dd:c25:c25b:d00a:dc22
362c19:dd:d9:dd:c25:c25b:d00a:dc23/1282c19:dd:d9:dd:c25:c25b:d00a:dc23
372c19:dd:d9:dd:c25:c25b:d00a:dc24/1282c19:dd:d9:dd:c25:c25b:d00a:dc24
382c19:dd:d9:dd:c25:c25b:d00a:dc25/1282c19:dd:d9:dd:c25:c25b:d00a:dc25
392c19:dd:d9:dd:c25:c25b:d00a:dc26/1282c19:dd:d9:dd:c25:c25b:d00a:dc26
402c19:dd:d9:dd:c25:c25b:d00a:dc27/1282c19:dd:d9:dd:c25:c25b:d00a:dc27
412c19:dd:d9:dd:c25:c25b:d00a:dc28/1282c19:dd:d9:dd:c25:c25b:d00a:dc28
422c19:dd:d9:dd:c25:c25b:d00a:dc29/1282c19:dd:d9:dd:c25:c25b:d00a:dc29
432c19:dd:d9:dd:c25:c25b:d00a:dc2a/1282c19:dd:d9:dd:c25:c25b:d00a:dc2a
442c19:dd:d9:dd:c25:c25b:d00a:dc2b/1282c19:dd:d9:dd:c25:c25b:d00a:dc2b
452c19:dd:d9:dd:c25:c25b:d00a:dc2c/1282c19:dd:d9:dd:c25:c25b:d00a:dc2c
462c19:dd:d9:dd:c25:c25b:d00a:dc2d/1282c19:dd:d9:dd:c25:c25b:d00a:dc2d
472c19:dd:d9:dd:c25:c25b:d00a:dc2e/1282c19:dd:d9:dd:c25:c25b:d00a:dc2e
482c19:dd:d9:dd:c25:c25b:d00a:dc2f/1282c19:dd:d9:dd:c25:c25b:d00a:dc2f
492c19:dd:d9:dd:c25:c25b:d00a:dc30/1282c19:dd:d9:dd:c25:c25b:d00a:dc30
502c19:dd:d9:dd:c25:c25b:d00a:dc31/1282c19:dd:d9:dd:c25:c25b:d00a:dc31
512c19:dd:d9:dd:c25:c25b:d00a:dc32/1282c19:dd:d9:dd:c25:c25b:d00a:dc32
522c19:dd:d9:dd:c25:c25b:d00a:dc33/1282c19:dd:d9:dd:c25:c25b:d00a:dc33
532c19:dd:d9:dd:c25:c25b:d00a:dc34/1282c19:dd:d9:dd:c25:c25b:d00a:dc34
542c19:dd:d9:dd:c25:c25b:d00a:dc35/1282c19:dd:d9:dd:c25:c25b:d00a:dc35
552c19:dd:d9:dd:c25:c25b:d00a:dc36/1282c19:dd:d9:dd:c25:c25b:d00a:dc36
562c19:dd:d9:dd:c25:c25b:d00a:dc37/1282c19:dd:d9:dd:c25:c25b:d00a:dc37
572c19:dd:d9:dd:c25:c25b:d00a:dc38/1282c19:dd:d9:dd:c25:c25b:d00a:dc38
582c19:dd:d9:dd:c25:c25b:d00a:dc39/1282c19:dd:d9:dd:c25:c25b:d00a:dc39
592c19:dd:d9:dd:c25:c25b:d00a:dc3a/1282c19:dd:d9:dd:c25:c25b:d00a:dc3a
602c19:dd:d9:dd:c25:c25b:d00a:dc3b/1282c19:dd:d9:dd:c25:c25b:d00a:dc3b
612c19:dd:d9:dd:c25:c25b:d00a:dc3c/1282c19:dd:d9:dd:c25:c25b:d00a:dc3c
622c19:dd:d9:dd:c25:c25b:d00a:dc3d/1282c19:dd:d9:dd:c25:c25b:d00a:dc3d
632c19:dd:d9:dd:c25:c25b:d00a:dc3e/1282c19:dd:d9:dd:c25:c25b:d00a:dc3e
642c19:dd:d9:dd:c25:c25b:d00a:dc3f/1282c19:dd:d9:dd:c25:c25b:d00a:dc3f
652c19:dd:d9:dd:c25:c25b:d00a:dc40/1282c19:dd:d9:dd:c25:c25b:d00a:dc40
662c19:dd:d9:dd:c25:c25b:d00a:dc41/1282c19:dd:d9:dd:c25:c25b:d00a:dc41
672c19:dd:d9:dd:c25:c25b:d00a:dc42/1282c19:dd:d9:dd:c25:c25b:d00a:dc42
682c19:dd:d9:dd:c25:c25b:d00a:dc43/1282c19:dd:d9:dd:c25:c25b:d00a:dc43
692c19:dd:d9:dd:c25:c25b:d00a:dc44/1282c19:dd:d9:dd:c25:c25b:d00a:dc44
702c19:dd:d9:dd:c25:c25b:d00a:dc45/1282c19:dd:d9:dd:c25:c25b:d00a:dc45
712c19:dd:d9:dd:c25:c25b:d00a:dc46/1282c19:dd:d9:dd:c25:c25b:d00a:dc46
722c19:dd:d9:dd:c25:c25b:d00a:dc47/1282c19:dd:d9:dd:c25:c25b:d00a:dc47
732c19:dd:d9:dd:c25:c25b:d00a:dc48/1282c19:dd:d9:dd:c25:c25b:d00a:dc48
742c19:dd:d9:dd:c25:c25b:d00a:dc49/1282c19:dd:d9:dd:c25:c25b:d00a:dc49
752c19:dd:d9:dd:c25:c25b:d00a:dc4a/1282c19:dd:d9:dd:c25:c25b:d00a:dc4a
762c19:dd:d9:dd:c25:c25b:d00a:dc4b/1282c19:dd:d9:dd:c25:c25b:d00a:dc4b
772c19:dd:d9:dd:c25:c25b:d00a:dc4c/1282c19:dd:d9:dd:c25:c25b:d00a:dc4c
782c19:dd:d9:dd:c25:c25b:d00a:dc4d/1282c19:dd:d9:dd:c25:c25b:d00a:dc4d
792c19:dd:d9:dd:c25:c25b:d00a:dc4e/1282c19:dd:d9:dd:c25:c25b:d00a:dc4e
802c19:dd:d9:dd:c25:c25b:d00a:dc4f/1282c19:dd:d9:dd:c25:c25b:d00a:dc4f
812c19:dd:d9:dd:c25:c25b:d00a:dc50/1282c19:dd:d9:dd:c25:c25b:d00a:dc50
822c19:dd:d9:dd:c25:c25b:d00a:dc51/1282c19:dd:d9:dd:c25:c25b:d00a:dc51
832c19:dd:d9:dd:c25:c25b:d00a:dc52/1282c19:dd:d9:dd:c25:c25b:d00a:dc52
842c19:dd:d9:dd:c25:c25b:d00a:dc53/1282c19:dd:d9:dd:c25:c25b:d00a:dc53
852c19:dd:d9:dd:c25:c25b:d00a:dc54/1282c19:dd:d9:dd:c25:c25b:d00a:dc54
862c19:dd:d9:dd:c25:c25b:d00a:dc55/1282c19:dd:d9:dd:c25:c25b:d00a:dc55
872c19:dd:d9:dd:c25:c25b:d00a:dc56/1282c19:dd:d9:dd:c25:c25b:d00a:dc56
882c19:dd:d9:dd:c25:c25b:d00a:dc57/1282c19:dd:d9:dd:c25:c25b:d00a:dc57
892c19:dd:d9:dd:c25:c25b:d00a:dc58/1282c19:dd:d9:dd:c25:c25b:d00a:dc58
902c19:dd:d9:dd:c25:c25b:d00a:dc59/1282c19:dd:d9:dd:c25:c25b:d00a:dc59
912c19:dd:d9:dd:c25:c25b:d00a:dc5a/1282c19:dd:d9:dd:c25:c25b:d00a:dc5a
922c19:dd:d9:dd:c25:c25b:d00a:dc5b/1282c19:dd:d9:dd:c25:c25b:d00a:dc5b
932c19:dd:d9:dd:c25:c25b:d00a:dc5c/1282c19:dd:d9:dd:c25:c25b:d00a:dc5c
942c19:dd:d9:dd:c25:c25b:d00a:dc5d/1282c19:dd:d9:dd:c25:c25b:d00a:dc5d
952c19:dd:d9:dd:c25:c25b:d00a:dc5e/1282c19:dd:d9:dd:c25:c25b:d00a:dc5e
962c19:dd:d9:dd:c25:c25b:d00a:dc5f/1282c19:dd:d9:dd:c25:c25b:d00a:dc5f
972c19:dd:d9:dd:c25:c25b:d00a:dc60/1282c19:dd:d9:dd:c25:c25b:d00a:dc60
982c19:dd:d9:dd:c25:c25b:d00a:dc61/1282c19:dd:d9:dd:c25:c25b:d00a:dc61
992c19:dd:d9:dd:c25:c25b:d00a:dc62/1282c19:dd:d9:dd:c25:c25b:d00a:dc62
1002c19:dd:d9:dd:c25:c25b:d00a:dc63/1282c19:dd:d9:dd:c25:c25b:d00a:dc63
1012c19:dd:d9:dd:c25:c25b:d00a:dc64/1282c19:dd:d9:dd:c25:c25b:d00a:dc64
1022c19:dd:d9:dd:c25:c25b:d00a:dc65/1282c19:dd:d9:dd:c25:c25b:d00a:dc65
1032c19:dd:d9:dd:c25:c25b:d00a:dc66/1282c19:dd:d9:dd:c25:c25b:d00a:dc66
1042c19:dd:d9:dd:c25:c25b:d00a:dc67/1282c19:dd:d9:dd:c25:c25b:d00a:dc67
1052c19:dd:d9:dd:c25:c25b:d00a:dc68/1282c19:dd:d9:dd:c25:c25b:d00a:dc68
1062c19:dd:d9:dd:c25:c25b:d00a:dc69/1282c19:dd:d9:dd:c25:c25b:d00a:dc69
1072c19:dd:d9:dd:c25:c25b:d00a:dc6a/1282c19:dd:d9:dd:c25:c25b:d00a:dc6a
1082c19:dd:d9:dd:c25:c25b:d00a:dc6b/1282c19:dd:d9:dd:c25:c25b:d00a:dc6b
1092c19:dd:d9:dd:c25:c25b:d00a:dc6c/1282c19:dd:d9:dd:c25:c25b:d00a:dc6c
1102c19:dd:d9:dd:c25:c25b:d00a:dc6d/1282c19:dd:d9:dd:c25:c25b:d00a:dc6d
1112c19:dd:d9:dd:c25:c25b:d00a:dc6e/1282c19:dd:d9:dd:c25:c25b:d00a:dc6e
1122c19:dd:d9:dd:c25:c25b:d00a:dc6f/1282c19:dd:d9:dd:c25:c25b:d00a:dc6f
1132c19:dd:d9:dd:c25:c25b:d00a:dc70/1282c19:dd:d9:dd:c25:c25b:d00a:dc70
1142c19:dd:d9:dd:c25:c25b:d00a:dc71/1282c19:dd:d9:dd:c25:c25b:d00a:dc71
1152c19:dd:d9:dd:c25:c25b:d00a:dc72/1282c19:dd:d9:dd:c25:c25b:d00a:dc72
1162c19:dd:d9:dd:c25:c25b:d00a:dc73/1282c19:dd:d9:dd:c25:c25b:d00a:dc73
1172c19:dd:d9:dd:c25:c25b:d00a:dc74/1282c19:dd:d9:dd:c25:c25b:d00a:dc74
1182c19:dd:d9:dd:c25:c25b:d00a:dc75/1282c19:dd:d9:dd:c25:c25b:d00a:dc75
1192c19:dd:d9:dd:c25:c25b:d00a:dc76/1282c19:dd:d9:dd:c25:c25b:d00a:dc76
1202c19:dd:d9:dd:c25:c25b:d00a:dc77/1282c19:dd:d9:dd:c25:c25b:d00a:dc77
1212c19:dd:d9:dd:c25:c25b:d00a:dc78/1282c19:dd:d9:dd:c25:c25b:d00a:dc78
1222c19:dd:d9:dd:c25:c25b:d00a:dc79/1282c19:dd:d9:dd:c25:c25b:d00a:dc79
1232c19:dd:d9:dd:c25:c25b:d00a:dc7a/1282c19:dd:d9:dd:c25:c25b:d00a:dc7a
1242c19:dd:d9:dd:c25:c25b:d00a:dc7b/1282c19:dd:d9:dd:c25:c25b:d00a:dc7b
1252c19:dd:d9:dd:c25:c25b:d00a:dc7c/1282c19:dd:d9:dd:c25:c25b:d00a:dc7c
1262c19:dd:d9:dd:c25:c25b:d00a:dc7d/1282c19:dd:d9:dd:c25:c25b:d00a:dc7d
1272c19:dd:d9:dd:c25:c25b:d00a:dc7e/1282c19:dd:d9:dd:c25:c25b:d00a:dc7e
1282c19:dd:d9:dd:c25:c25b:d00a:dc7f/1282c19:dd:d9:dd:c25:c25b:d00a:dc7f
1292c19:dd:d9:dd:c25:c25b:d00a:dc80/1282c19:dd:d9:dd:c25:c25b:d00a:dc80
1302c19:dd:d9:dd:c25:c25b:d00a:dc81/1282c19:dd:d9:dd:c25:c25b:d00a:dc81
1312c19:dd:d9:dd:c25:c25b:d00a:dc82/1282c19:dd:d9:dd:c25:c25b:d00a:dc82
1322c19:dd:d9:dd:c25:c25b:d00a:dc83/1282c19:dd:d9:dd:c25:c25b:d00a:dc83
1332c19:dd:d9:dd:c25:c25b:d00a:dc84/1282c19:dd:d9:dd:c25:c25b:d00a:dc84
1342c19:dd:d9:dd:c25:c25b:d00a:dc85/1282c19:dd:d9:dd:c25:c25b:d00a:dc85
1352c19:dd:d9:dd:c25:c25b:d00a:dc86/1282c19:dd:d9:dd:c25:c25b:d00a:dc86
1362c19:dd:d9:dd:c25:c25b:d00a:dc87/1282c19:dd:d9:dd:c25:c25b:d00a:dc87
1372c19:dd:d9:dd:c25:c25b:d00a:dc88/1282c19:dd:d9:dd:c25:c25b:d00a:dc88
1382c19:dd:d9:dd:c25:c25b:d00a:dc89/1282c19:dd:d9:dd:c25:c25b:d00a:dc89
1392c19:dd:d9:dd:c25:c25b:d00a:dc8a/1282c19:dd:d9:dd:c25:c25b:d00a:dc8a
1402c19:dd:d9:dd:c25:c25b:d00a:dc8b/1282c19:dd:d9:dd:c25:c25b:d00a:dc8b
1412c19:dd:d9:dd:c25:c25b:d00a:dc8c/1282c19:dd:d9:dd:c25:c25b:d00a:dc8c
1422c19:dd:d9:dd:c25:c25b:d00a:dc8d/1282c19:dd:d9:dd:c25:c25b:d00a:dc8d
1432c19:dd:d9:dd:c25:c25b:d00a:dc8e/1282c19:dd:d9:dd:c25:c25b:d00a:dc8e
1442c19:dd:d9:dd:c25:c25b:d00a:dc8f/1282c19:dd:d9:dd:c25:c25b:d00a:dc8f
1452c19:dd:d9:dd:c25:c25b:d00a:dc90/1282c19:dd:d9:dd:c25:c25b:d00a:dc90
1462c19:dd:d9:dd:c25:c25b:d00a:dc91/1282c19:dd:d9:dd:c25:c25b:d00a:dc91
1472c19:dd:d9:dd:c25:c25b:d00a:dc92/1282c19:dd:d9:dd:c25:c25b:d00a:dc92
1482c19:dd:d9:dd:c25:c25b:d00a:dc93/1282c19:dd:d9:dd:c25:c25b:d00a:dc93
1492c19:dd:d9:dd:c25:c25b:d00a:dc94/1282c19:dd:d9:dd:c25:c25b:d00a:dc94
1502c19:dd:d9:dd:c25:c25b:d00a:dc95/1282c19:dd:d9:dd:c25:c25b:d00a:dc95
1512c19:dd:d9:dd:c25:c25b:d00a:dc96/1282c19:dd:d9:dd:c25:c25b:d00a:dc96
1522c19:dd:d9:dd:c25:c25b:d00a:dc97/1282c19:dd:d9:dd:c25:c25b:d00a:dc97
1532c19:dd:d9:dd:c25:c25b:d00a:dc98/1282c19:dd:d9:dd:c25:c25b:d00a:dc98
1542c19:dd:d9:dd:c25:c25b:d00a:dc99/1282c19:dd:d9:dd:c25:c25b:d00a:dc99
1552c19:dd:d9:dd:c25:c25b:d00a:dc9a/1282c19:dd:d9:dd:c25:c25b:d00a:dc9a
1562c19:dd:d9:dd:c25:c25b:d00a:dc9b/1282c19:dd:d9:dd:c25:c25b:d00a:dc9b
1572c19:dd:d9:dd:c25:c25b:d00a:dc9c/1282c19:dd:d9:dd:c25:c25b:d00a:dc9c
1582c19:dd:d9:dd:c25:c25b:d00a:dc9d/1282c19:dd:d9:dd:c25:c25b:d00a:dc9d
1592c19:dd:d9:dd:c25:c25b:d00a:dc9e/1282c19:dd:d9:dd:c25:c25b:d00a:dc9e
1602c19:dd:d9:dd:c25:c25b:d00a:dc9f/1282c19:dd:d9:dd:c25:c25b:d00a:dc9f
1612c19:dd:d9:dd:c25:c25b:d00a:dca0/1282c19:dd:d9:dd:c25:c25b:d00a:dca0
1622c19:dd:d9:dd:c25:c25b:d00a:dca1/1282c19:dd:d9:dd:c25:c25b:d00a:dca1
1632c19:dd:d9:dd:c25:c25b:d00a:dca2/1282c19:dd:d9:dd:c25:c25b:d00a:dca2
1642c19:dd:d9:dd:c25:c25b:d00a:dca3/1282c19:dd:d9:dd:c25:c25b:d00a:dca3
1652c19:dd:d9:dd:c25:c25b:d00a:dca4/1282c19:dd:d9:dd:c25:c25b:d00a:dca4
1662c19:dd:d9:dd:c25:c25b:d00a:dca5/1282c19:dd:d9:dd:c25:c25b:d00a:dca5
1672c19:dd:d9:dd:c25:c25b:d00a:dca6/1282c19:dd:d9:dd:c25:c25b:d00a:dca6
1682c19:dd:d9:dd:c25:c25b:d00a:dca7/1282c19:dd:d9:dd:c25:c25b:d00a:dca7
1692c19:dd:d9:dd:c25:c25b:d00a:dca8/1282c19:dd:d9:dd:c25:c25b:d00a:dca8
1702c19:dd:d9:dd:c25:c25b:d00a:dca9/1282c19:dd:d9:dd:c25:c25b:d00a:dca9
1712c19:dd:d9:dd:c25:c25b:d00a:dcaa/1282c19:dd:d9:dd:c25:c25b:d00a:dcaa
1722c19:dd:d9:dd:c25:c25b:d00a:dcab/1282c19:dd:d9:dd:c25:c25b:d00a:dcab
1732c19:dd:d9:dd:c25:c25b:d00a:dcac/1282c19:dd:d9:dd:c25:c25b:d00a:dcac
1742c19:dd:d9:dd:c25:c25b:d00a:dcad/1282c19:dd:d9:dd:c25:c25b:d00a:dcad
1752c19:dd:d9:dd:c25:c25b:d00a:dcae/1282c19:dd:d9:dd:c25:c25b:d00a:dcae
1762c19:dd:d9:dd:c25:c25b:d00a:dcaf/1282c19:dd:d9:dd:c25:c25b:d00a:dcaf
1772c19:dd:d9:dd:c25:c25b:d00a:dcb0/1282c19:dd:d9:dd:c25:c25b:d00a:dcb0
1782c19:dd:d9:dd:c25:c25b:d00a:dcb1/1282c19:dd:d9:dd:c25:c25b:d00a:dcb1
1792c19:dd:d9:dd:c25:c25b:d00a:dcb2/1282c19:dd:d9:dd:c25:c25b:d00a:dcb2
1802c19:dd:d9:dd:c25:c25b:d00a:dcb3/1282c19:dd:d9:dd:c25:c25b:d00a:dcb3
1812c19:dd:d9:dd:c25:c25b:d00a:dcb4/1282c19:dd:d9:dd:c25:c25b:d00a:dcb4
1822c19:dd:d9:dd:c25:c25b:d00a:dcb5/1282c19:dd:d9:dd:c25:c25b:d00a:dcb5
1832c19:dd:d9:dd:c25:c25b:d00a:dcb6/1282c19:dd:d9:dd:c25:c25b:d00a:dcb6
1842c19:dd:d9:dd:c25:c25b:d00a:dcb7/1282c19:dd:d9:dd:c25:c25b:d00a:dcb7
1852c19:dd:d9:dd:c25:c25b:d00a:dcb8/1282c19:dd:d9:dd:c25:c25b:d00a:dcb8
1862c19:dd:d9:dd:c25:c25b:d00a:dcb9/1282c19:dd:d9:dd:c25:c25b:d00a:dcb9
1872c19:dd:d9:dd:c25:c25b:d00a:dcba/1282c19:dd:d9:dd:c25:c25b:d00a:dcba
1882c19:dd:d9:dd:c25:c25b:d00a:dcbb/1282c19:dd:d9:dd:c25:c25b:d00a:dcbb
1892c19:dd:d9:dd:c25:c25b:d00a:dcbc/1282c19:dd:d9:dd:c25:c25b:d00a:dcbc
1902c19:dd:d9:dd:c25:c25b:d00a:dcbd/1282c19:dd:d9:dd:c25:c25b:d00a:dcbd
1912c19:dd:d9:dd:c25:c25b:d00a:dcbe/1282c19:dd:d9:dd:c25:c25b:d00a:dcbe
1922c19:dd:d9:dd:c25:c25b:d00a:dcbf/1282c19:dd:d9:dd:c25:c25b:d00a:dcbf
1932c19:dd:d9:dd:c25:c25b:d00a:dcc0/1282c19:dd:d9:dd:c25:c25b:d00a:dcc0
1942c19:dd:d9:dd:c25:c25b:d00a:dcc1/1282c19:dd:d9:dd:c25:c25b:d00a:dcc1
1952c19:dd:d9:dd:c25:c25b:d00a:dcc2/1282c19:dd:d9:dd:c25:c25b:d00a:dcc2
1962c19:dd:d9:dd:c25:c25b:d00a:dcc3/1282c19:dd:d9:dd:c25:c25b:d00a:dcc3
1972c19:dd:d9:dd:c25:c25b:d00a:dcc4/1282c19:dd:d9:dd:c25:c25b:d00a:dcc4
1982c19:dd:d9:dd:c25:c25b:d00a:dcc5/1282c19:dd:d9:dd:c25:c25b:d00a:dcc5
1992c19:dd:d9:dd:c25:c25b:d00a:dcc6/1282c19:dd:d9:dd:c25:c25b:d00a:dcc6
2002c19:dd:d9:dd:c25:c25b:d00a:dcc7/1282c19:dd:d9:dd:c25:c25b:d00a:dcc7
2012c19:dd:d9:dd:c25:c25b:d00a:dcc8/1282c19:dd:d9:dd:c25:c25b:d00a:dcc8
2022c19:dd:d9:dd:c25:c25b:d00a:dcc9/1282c19:dd:d9:dd:c25:c25b:d00a:dcc9
2032c19:dd:d9:dd:c25:c25b:d00a:dcca/1282c19:dd:d9:dd:c25:c25b:d00a:dcca
2042c19:dd:d9:dd:c25:c25b:d00a:dccb/1282c19:dd:d9:dd:c25:c25b:d00a:dccb
2052c19:dd:d9:dd:c25:c25b:d00a:dccc/1282c19:dd:d9:dd:c25:c25b:d00a:dccc
2062c19:dd:d9:dd:c25:c25b:d00a:dccd/1282c19:dd:d9:dd:c25:c25b:d00a:dccd
2072c19:dd:d9:dd:c25:c25b:d00a:dcce/1282c19:dd:d9:dd:c25:c25b:d00a:dcce
2082c19:dd:d9:dd:c25:c25b:d00a:dccf/1282c19:dd:d9:dd:c25:c25b:d00a:dccf
2092c19:dd:d9:dd:c25:c25b:d00a:dcd0/1282c19:dd:d9:dd:c25:c25b:d00a:dcd0
2102c19:dd:d9:dd:c25:c25b:d00a:dcd1/1282c19:dd:d9:dd:c25:c25b:d00a:dcd1
2112c19:dd:d9:dd:c25:c25b:d00a:dcd2/1282c19:dd:d9:dd:c25:c25b:d00a:dcd2
2122c19:dd:d9:dd:c25:c25b:d00a:dcd3/1282c19:dd:d9:dd:c25:c25b:d00a:dcd3
2132c19:dd:d9:dd:c25:c25b:d00a:dcd4/1282c19:dd:d9:dd:c25:c25b:d00a:dcd4
2142c19:dd:d9:dd:c25:c25b:d00a:dcd5/1282c19:dd:d9:dd:c25:c25b:d00a:dcd5
2152c19:dd:d9:dd:c25:c25b:d00a:dcd6/1282c19:dd:d9:dd:c25:c25b:d00a:dcd6
2162c19:dd:d9:dd:c25:c25b:d00a:dcd7/1282c19:dd:d9:dd:c25:c25b:d00a:dcd7
2172c19:dd:d9:dd:c25:c25b:d00a:dcd8/1282c19:dd:d9:dd:c25:c25b:d00a:dcd8
2182c19:dd:d9:dd:c25:c25b:d00a:dcd9/1282c19:dd:d9:dd:c25:c25b:d00a:dcd9
2192c19:dd:d9:dd:c25:c25b:d00a:dcda/1282c19:dd:d9:dd:c25:c25b:d00a:dcda
2202c19:dd:d9:dd:c25:c25b:d00a:dcdb/1282c19:dd:d9:dd:c25:c25b:d00a:dcdb
2212c19:dd:d9:dd:c25:c25b:d00a:dcdc/1282c19:dd:d9:dd:c25:c25b:d00a:dcdc
2222c19:dd:d9:dd:c25:c25b:d00a:dcdd/1282c19:dd:d9:dd:c25:c25b:d00a:dcdd
2232c19:dd:d9:dd:c25:c25b:d00a:dcde/1282c19:dd:d9:dd:c25:c25b:d00a:dcde
2242c19:dd:d9:dd:c25:c25b:d00a:dcdf/1282c19:dd:d9:dd:c25:c25b:d00a:dcdf
2252c19:dd:d9:dd:c25:c25b:d00a:dce0/1282c19:dd:d9:dd:c25:c25b:d00a:dce0
2262c19:dd:d9:dd:c25:c25b:d00a:dce1/1282c19:dd:d9:dd:c25:c25b:d00a:dce1
2272c19:dd:d9:dd:c25:c25b:d00a:dce2/1282c19:dd:d9:dd:c25:c25b:d00a:dce2
2282c19:dd:d9:dd:c25:c25b:d00a:dce3/1282c19:dd:d9:dd:c25:c25b:d00a:dce3
2292c19:dd:d9:dd:c25:c25b:d00a:dce4/1282c19:dd:d9:dd:c25:c25b:d00a:dce4
2302c19:dd:d9:dd:c25:c25b:d00a:dce5/1282c19:dd:d9:dd:c25:c25b:d00a:dce5
2312c19:dd:d9:dd:c25:c25b:d00a:dce6/1282c19:dd:d9:dd:c25:c25b:d00a:dce6
2322c19:dd:d9:dd:c25:c25b:d00a:dce7/1282c19:dd:d9:dd:c25:c25b:d00a:dce7
2332c19:dd:d9:dd:c25:c25b:d00a:dce8/1282c19:dd:d9:dd:c25:c25b:d00a:dce8
2342c19:dd:d9:dd:c25:c25b:d00a:dce9/1282c19:dd:d9:dd:c25:c25b:d00a:dce9
2352c19:dd:d9:dd:c25:c25b:d00a:dcea/1282c19:dd:d9:dd:c25:c25b:d00a:dcea
2362c19:dd:d9:dd:c25:c25b:d00a:dceb/1282c19:dd:d9:dd:c25:c25b:d00a:dceb
2372c19:dd:d9:dd:c25:c25b:d00a:dcec/1282c19:dd:d9:dd:c25:c25b:d00a:dcec
2382c19:dd:d9:dd:c25:c25b:d00a:dced/1282c19:dd:d9:dd:c25:c25b:d00a:dced
2392c19:dd:d9:dd:c25:c25b:d00a:dcee/1282c19:dd:d9:dd:c25:c25b:d00a:dcee
2402c19:dd:d9:dd:c25:c25b:d00a:dcef/1282c19:dd:d9:dd:c25:c25b:d00a:dcef
2412c19:dd:d9:dd:c25:c25b:d00a:dcf0/1282c19:dd:d9:dd:c25:c25b:d00a:dcf0
2422c19:dd:d9:dd:c25:c25b:d00a:dcf1/1282c19:dd:d9:dd:c25:c25b:d00a:dcf1
2432c19:dd:d9:dd:c25:c25b:d00a:dcf2/1282c19:dd:d9:dd:c25:c25b:d00a:dcf2
2442c19:dd:d9:dd:c25:c25b:d00a:dcf3/1282c19:dd:d9:dd:c25:c25b:d00a:dcf3
2452c19:dd:d9:dd:c25:c25b:d00a:dcf4/1282c19:dd:d9:dd:c25:c25b:d00a:dcf4
2462c19:dd:d9:dd:c25:c25b:d00a:dcf5/1282c19:dd:d9:dd:c25:c25b:d00a:dcf5
2472c19:dd:d9:dd:c25:c25b:d00a:dcf6/1282c19:dd:d9:dd:c25:c25b:d00a:dcf6
2482c19:dd:d9:dd:c25:c25b:d00a:dcf7/1282c19:dd:d9:dd:c25:c25b:d00a:dcf7
2492c19:dd:d9:dd:c25:c25b:d00a:dcf8/1282c19:dd:d9:dd:c25:c25b:d00a:dcf8
2502c19:dd:d9:dd:c25:c25b:d00a:dcf9/1282c19:dd:d9:dd:c25:c25b:d00a:dcf9
2512c19:dd:d9:dd:c25:c25b:d00a:dcfa/1282c19:dd:d9:dd:c25:c25b:d00a:dcfa
2522c19:dd:d9:dd:c25:c25b:d00a:dcfb/1282c19:dd:d9:dd:c25:c25b:d00a:dcfb
2532c19:dd:d9:dd:c25:c25b:d00a:dcfc/1282c19:dd:d9:dd:c25:c25b:d00a:dcfc
2542c19:dd:d9:dd:c25:c25b:d00a:dcfd/1282c19:dd:d9:dd:c25:c25b:d00a:dcfd
2552c19:dd:d9:dd:c25:c25b:d00a:dcfe/1282c19:dd:d9:dd:c25:c25b:d00a:dcfe
2562c19:dd:d9:dd:c25:c25b:d00a:dcff/1282c19:dd:d9:dd:c25:c25b:d00a:dcff

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.