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:c500:ec00/120
First address
2c19:dd:d9:dd:c25:c25:c500:ec00
Last address
2c19:dd:d9:dd:c25:c25:c500:ecff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:c500:ec00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
c.e.0.0.5.c.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:c500:ec00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:c500:ec00/1282c19:dd:d9:dd:c25:c25:c500:ec00
22c19:dd:d9:dd:c25:c25:c500:ec01/1282c19:dd:d9:dd:c25:c25:c500:ec01
32c19:dd:d9:dd:c25:c25:c500:ec02/1282c19:dd:d9:dd:c25:c25:c500:ec02
42c19:dd:d9:dd:c25:c25:c500:ec03/1282c19:dd:d9:dd:c25:c25:c500:ec03
52c19:dd:d9:dd:c25:c25:c500:ec04/1282c19:dd:d9:dd:c25:c25:c500:ec04
62c19:dd:d9:dd:c25:c25:c500:ec05/1282c19:dd:d9:dd:c25:c25:c500:ec05
72c19:dd:d9:dd:c25:c25:c500:ec06/1282c19:dd:d9:dd:c25:c25:c500:ec06
82c19:dd:d9:dd:c25:c25:c500:ec07/1282c19:dd:d9:dd:c25:c25:c500:ec07
92c19:dd:d9:dd:c25:c25:c500:ec08/1282c19:dd:d9:dd:c25:c25:c500:ec08
102c19:dd:d9:dd:c25:c25:c500:ec09/1282c19:dd:d9:dd:c25:c25:c500:ec09
112c19:dd:d9:dd:c25:c25:c500:ec0a/1282c19:dd:d9:dd:c25:c25:c500:ec0a
122c19:dd:d9:dd:c25:c25:c500:ec0b/1282c19:dd:d9:dd:c25:c25:c500:ec0b
132c19:dd:d9:dd:c25:c25:c500:ec0c/1282c19:dd:d9:dd:c25:c25:c500:ec0c
142c19:dd:d9:dd:c25:c25:c500:ec0d/1282c19:dd:d9:dd:c25:c25:c500:ec0d
152c19:dd:d9:dd:c25:c25:c500:ec0e/1282c19:dd:d9:dd:c25:c25:c500:ec0e
162c19:dd:d9:dd:c25:c25:c500:ec0f/1282c19:dd:d9:dd:c25:c25:c500:ec0f
172c19:dd:d9:dd:c25:c25:c500:ec10/1282c19:dd:d9:dd:c25:c25:c500:ec10
182c19:dd:d9:dd:c25:c25:c500:ec11/1282c19:dd:d9:dd:c25:c25:c500:ec11
192c19:dd:d9:dd:c25:c25:c500:ec12/1282c19:dd:d9:dd:c25:c25:c500:ec12
202c19:dd:d9:dd:c25:c25:c500:ec13/1282c19:dd:d9:dd:c25:c25:c500:ec13
212c19:dd:d9:dd:c25:c25:c500:ec14/1282c19:dd:d9:dd:c25:c25:c500:ec14
222c19:dd:d9:dd:c25:c25:c500:ec15/1282c19:dd:d9:dd:c25:c25:c500:ec15
232c19:dd:d9:dd:c25:c25:c500:ec16/1282c19:dd:d9:dd:c25:c25:c500:ec16
242c19:dd:d9:dd:c25:c25:c500:ec17/1282c19:dd:d9:dd:c25:c25:c500:ec17
252c19:dd:d9:dd:c25:c25:c500:ec18/1282c19:dd:d9:dd:c25:c25:c500:ec18
262c19:dd:d9:dd:c25:c25:c500:ec19/1282c19:dd:d9:dd:c25:c25:c500:ec19
272c19:dd:d9:dd:c25:c25:c500:ec1a/1282c19:dd:d9:dd:c25:c25:c500:ec1a
282c19:dd:d9:dd:c25:c25:c500:ec1b/1282c19:dd:d9:dd:c25:c25:c500:ec1b
292c19:dd:d9:dd:c25:c25:c500:ec1c/1282c19:dd:d9:dd:c25:c25:c500:ec1c
302c19:dd:d9:dd:c25:c25:c500:ec1d/1282c19:dd:d9:dd:c25:c25:c500:ec1d
312c19:dd:d9:dd:c25:c25:c500:ec1e/1282c19:dd:d9:dd:c25:c25:c500:ec1e
322c19:dd:d9:dd:c25:c25:c500:ec1f/1282c19:dd:d9:dd:c25:c25:c500:ec1f
332c19:dd:d9:dd:c25:c25:c500:ec20/1282c19:dd:d9:dd:c25:c25:c500:ec20
342c19:dd:d9:dd:c25:c25:c500:ec21/1282c19:dd:d9:dd:c25:c25:c500:ec21
352c19:dd:d9:dd:c25:c25:c500:ec22/1282c19:dd:d9:dd:c25:c25:c500:ec22
362c19:dd:d9:dd:c25:c25:c500:ec23/1282c19:dd:d9:dd:c25:c25:c500:ec23
372c19:dd:d9:dd:c25:c25:c500:ec24/1282c19:dd:d9:dd:c25:c25:c500:ec24
382c19:dd:d9:dd:c25:c25:c500:ec25/1282c19:dd:d9:dd:c25:c25:c500:ec25
392c19:dd:d9:dd:c25:c25:c500:ec26/1282c19:dd:d9:dd:c25:c25:c500:ec26
402c19:dd:d9:dd:c25:c25:c500:ec27/1282c19:dd:d9:dd:c25:c25:c500:ec27
412c19:dd:d9:dd:c25:c25:c500:ec28/1282c19:dd:d9:dd:c25:c25:c500:ec28
422c19:dd:d9:dd:c25:c25:c500:ec29/1282c19:dd:d9:dd:c25:c25:c500:ec29
432c19:dd:d9:dd:c25:c25:c500:ec2a/1282c19:dd:d9:dd:c25:c25:c500:ec2a
442c19:dd:d9:dd:c25:c25:c500:ec2b/1282c19:dd:d9:dd:c25:c25:c500:ec2b
452c19:dd:d9:dd:c25:c25:c500:ec2c/1282c19:dd:d9:dd:c25:c25:c500:ec2c
462c19:dd:d9:dd:c25:c25:c500:ec2d/1282c19:dd:d9:dd:c25:c25:c500:ec2d
472c19:dd:d9:dd:c25:c25:c500:ec2e/1282c19:dd:d9:dd:c25:c25:c500:ec2e
482c19:dd:d9:dd:c25:c25:c500:ec2f/1282c19:dd:d9:dd:c25:c25:c500:ec2f
492c19:dd:d9:dd:c25:c25:c500:ec30/1282c19:dd:d9:dd:c25:c25:c500:ec30
502c19:dd:d9:dd:c25:c25:c500:ec31/1282c19:dd:d9:dd:c25:c25:c500:ec31
512c19:dd:d9:dd:c25:c25:c500:ec32/1282c19:dd:d9:dd:c25:c25:c500:ec32
522c19:dd:d9:dd:c25:c25:c500:ec33/1282c19:dd:d9:dd:c25:c25:c500:ec33
532c19:dd:d9:dd:c25:c25:c500:ec34/1282c19:dd:d9:dd:c25:c25:c500:ec34
542c19:dd:d9:dd:c25:c25:c500:ec35/1282c19:dd:d9:dd:c25:c25:c500:ec35
552c19:dd:d9:dd:c25:c25:c500:ec36/1282c19:dd:d9:dd:c25:c25:c500:ec36
562c19:dd:d9:dd:c25:c25:c500:ec37/1282c19:dd:d9:dd:c25:c25:c500:ec37
572c19:dd:d9:dd:c25:c25:c500:ec38/1282c19:dd:d9:dd:c25:c25:c500:ec38
582c19:dd:d9:dd:c25:c25:c500:ec39/1282c19:dd:d9:dd:c25:c25:c500:ec39
592c19:dd:d9:dd:c25:c25:c500:ec3a/1282c19:dd:d9:dd:c25:c25:c500:ec3a
602c19:dd:d9:dd:c25:c25:c500:ec3b/1282c19:dd:d9:dd:c25:c25:c500:ec3b
612c19:dd:d9:dd:c25:c25:c500:ec3c/1282c19:dd:d9:dd:c25:c25:c500:ec3c
622c19:dd:d9:dd:c25:c25:c500:ec3d/1282c19:dd:d9:dd:c25:c25:c500:ec3d
632c19:dd:d9:dd:c25:c25:c500:ec3e/1282c19:dd:d9:dd:c25:c25:c500:ec3e
642c19:dd:d9:dd:c25:c25:c500:ec3f/1282c19:dd:d9:dd:c25:c25:c500:ec3f
652c19:dd:d9:dd:c25:c25:c500:ec40/1282c19:dd:d9:dd:c25:c25:c500:ec40
662c19:dd:d9:dd:c25:c25:c500:ec41/1282c19:dd:d9:dd:c25:c25:c500:ec41
672c19:dd:d9:dd:c25:c25:c500:ec42/1282c19:dd:d9:dd:c25:c25:c500:ec42
682c19:dd:d9:dd:c25:c25:c500:ec43/1282c19:dd:d9:dd:c25:c25:c500:ec43
692c19:dd:d9:dd:c25:c25:c500:ec44/1282c19:dd:d9:dd:c25:c25:c500:ec44
702c19:dd:d9:dd:c25:c25:c500:ec45/1282c19:dd:d9:dd:c25:c25:c500:ec45
712c19:dd:d9:dd:c25:c25:c500:ec46/1282c19:dd:d9:dd:c25:c25:c500:ec46
722c19:dd:d9:dd:c25:c25:c500:ec47/1282c19:dd:d9:dd:c25:c25:c500:ec47
732c19:dd:d9:dd:c25:c25:c500:ec48/1282c19:dd:d9:dd:c25:c25:c500:ec48
742c19:dd:d9:dd:c25:c25:c500:ec49/1282c19:dd:d9:dd:c25:c25:c500:ec49
752c19:dd:d9:dd:c25:c25:c500:ec4a/1282c19:dd:d9:dd:c25:c25:c500:ec4a
762c19:dd:d9:dd:c25:c25:c500:ec4b/1282c19:dd:d9:dd:c25:c25:c500:ec4b
772c19:dd:d9:dd:c25:c25:c500:ec4c/1282c19:dd:d9:dd:c25:c25:c500:ec4c
782c19:dd:d9:dd:c25:c25:c500:ec4d/1282c19:dd:d9:dd:c25:c25:c500:ec4d
792c19:dd:d9:dd:c25:c25:c500:ec4e/1282c19:dd:d9:dd:c25:c25:c500:ec4e
802c19:dd:d9:dd:c25:c25:c500:ec4f/1282c19:dd:d9:dd:c25:c25:c500:ec4f
812c19:dd:d9:dd:c25:c25:c500:ec50/1282c19:dd:d9:dd:c25:c25:c500:ec50
822c19:dd:d9:dd:c25:c25:c500:ec51/1282c19:dd:d9:dd:c25:c25:c500:ec51
832c19:dd:d9:dd:c25:c25:c500:ec52/1282c19:dd:d9:dd:c25:c25:c500:ec52
842c19:dd:d9:dd:c25:c25:c500:ec53/1282c19:dd:d9:dd:c25:c25:c500:ec53
852c19:dd:d9:dd:c25:c25:c500:ec54/1282c19:dd:d9:dd:c25:c25:c500:ec54
862c19:dd:d9:dd:c25:c25:c500:ec55/1282c19:dd:d9:dd:c25:c25:c500:ec55
872c19:dd:d9:dd:c25:c25:c500:ec56/1282c19:dd:d9:dd:c25:c25:c500:ec56
882c19:dd:d9:dd:c25:c25:c500:ec57/1282c19:dd:d9:dd:c25:c25:c500:ec57
892c19:dd:d9:dd:c25:c25:c500:ec58/1282c19:dd:d9:dd:c25:c25:c500:ec58
902c19:dd:d9:dd:c25:c25:c500:ec59/1282c19:dd:d9:dd:c25:c25:c500:ec59
912c19:dd:d9:dd:c25:c25:c500:ec5a/1282c19:dd:d9:dd:c25:c25:c500:ec5a
922c19:dd:d9:dd:c25:c25:c500:ec5b/1282c19:dd:d9:dd:c25:c25:c500:ec5b
932c19:dd:d9:dd:c25:c25:c500:ec5c/1282c19:dd:d9:dd:c25:c25:c500:ec5c
942c19:dd:d9:dd:c25:c25:c500:ec5d/1282c19:dd:d9:dd:c25:c25:c500:ec5d
952c19:dd:d9:dd:c25:c25:c500:ec5e/1282c19:dd:d9:dd:c25:c25:c500:ec5e
962c19:dd:d9:dd:c25:c25:c500:ec5f/1282c19:dd:d9:dd:c25:c25:c500:ec5f
972c19:dd:d9:dd:c25:c25:c500:ec60/1282c19:dd:d9:dd:c25:c25:c500:ec60
982c19:dd:d9:dd:c25:c25:c500:ec61/1282c19:dd:d9:dd:c25:c25:c500:ec61
992c19:dd:d9:dd:c25:c25:c500:ec62/1282c19:dd:d9:dd:c25:c25:c500:ec62
1002c19:dd:d9:dd:c25:c25:c500:ec63/1282c19:dd:d9:dd:c25:c25:c500:ec63
1012c19:dd:d9:dd:c25:c25:c500:ec64/1282c19:dd:d9:dd:c25:c25:c500:ec64
1022c19:dd:d9:dd:c25:c25:c500:ec65/1282c19:dd:d9:dd:c25:c25:c500:ec65
1032c19:dd:d9:dd:c25:c25:c500:ec66/1282c19:dd:d9:dd:c25:c25:c500:ec66
1042c19:dd:d9:dd:c25:c25:c500:ec67/1282c19:dd:d9:dd:c25:c25:c500:ec67
1052c19:dd:d9:dd:c25:c25:c500:ec68/1282c19:dd:d9:dd:c25:c25:c500:ec68
1062c19:dd:d9:dd:c25:c25:c500:ec69/1282c19:dd:d9:dd:c25:c25:c500:ec69
1072c19:dd:d9:dd:c25:c25:c500:ec6a/1282c19:dd:d9:dd:c25:c25:c500:ec6a
1082c19:dd:d9:dd:c25:c25:c500:ec6b/1282c19:dd:d9:dd:c25:c25:c500:ec6b
1092c19:dd:d9:dd:c25:c25:c500:ec6c/1282c19:dd:d9:dd:c25:c25:c500:ec6c
1102c19:dd:d9:dd:c25:c25:c500:ec6d/1282c19:dd:d9:dd:c25:c25:c500:ec6d
1112c19:dd:d9:dd:c25:c25:c500:ec6e/1282c19:dd:d9:dd:c25:c25:c500:ec6e
1122c19:dd:d9:dd:c25:c25:c500:ec6f/1282c19:dd:d9:dd:c25:c25:c500:ec6f
1132c19:dd:d9:dd:c25:c25:c500:ec70/1282c19:dd:d9:dd:c25:c25:c500:ec70
1142c19:dd:d9:dd:c25:c25:c500:ec71/1282c19:dd:d9:dd:c25:c25:c500:ec71
1152c19:dd:d9:dd:c25:c25:c500:ec72/1282c19:dd:d9:dd:c25:c25:c500:ec72
1162c19:dd:d9:dd:c25:c25:c500:ec73/1282c19:dd:d9:dd:c25:c25:c500:ec73
1172c19:dd:d9:dd:c25:c25:c500:ec74/1282c19:dd:d9:dd:c25:c25:c500:ec74
1182c19:dd:d9:dd:c25:c25:c500:ec75/1282c19:dd:d9:dd:c25:c25:c500:ec75
1192c19:dd:d9:dd:c25:c25:c500:ec76/1282c19:dd:d9:dd:c25:c25:c500:ec76
1202c19:dd:d9:dd:c25:c25:c500:ec77/1282c19:dd:d9:dd:c25:c25:c500:ec77
1212c19:dd:d9:dd:c25:c25:c500:ec78/1282c19:dd:d9:dd:c25:c25:c500:ec78
1222c19:dd:d9:dd:c25:c25:c500:ec79/1282c19:dd:d9:dd:c25:c25:c500:ec79
1232c19:dd:d9:dd:c25:c25:c500:ec7a/1282c19:dd:d9:dd:c25:c25:c500:ec7a
1242c19:dd:d9:dd:c25:c25:c500:ec7b/1282c19:dd:d9:dd:c25:c25:c500:ec7b
1252c19:dd:d9:dd:c25:c25:c500:ec7c/1282c19:dd:d9:dd:c25:c25:c500:ec7c
1262c19:dd:d9:dd:c25:c25:c500:ec7d/1282c19:dd:d9:dd:c25:c25:c500:ec7d
1272c19:dd:d9:dd:c25:c25:c500:ec7e/1282c19:dd:d9:dd:c25:c25:c500:ec7e
1282c19:dd:d9:dd:c25:c25:c500:ec7f/1282c19:dd:d9:dd:c25:c25:c500:ec7f
1292c19:dd:d9:dd:c25:c25:c500:ec80/1282c19:dd:d9:dd:c25:c25:c500:ec80
1302c19:dd:d9:dd:c25:c25:c500:ec81/1282c19:dd:d9:dd:c25:c25:c500:ec81
1312c19:dd:d9:dd:c25:c25:c500:ec82/1282c19:dd:d9:dd:c25:c25:c500:ec82
1322c19:dd:d9:dd:c25:c25:c500:ec83/1282c19:dd:d9:dd:c25:c25:c500:ec83
1332c19:dd:d9:dd:c25:c25:c500:ec84/1282c19:dd:d9:dd:c25:c25:c500:ec84
1342c19:dd:d9:dd:c25:c25:c500:ec85/1282c19:dd:d9:dd:c25:c25:c500:ec85
1352c19:dd:d9:dd:c25:c25:c500:ec86/1282c19:dd:d9:dd:c25:c25:c500:ec86
1362c19:dd:d9:dd:c25:c25:c500:ec87/1282c19:dd:d9:dd:c25:c25:c500:ec87
1372c19:dd:d9:dd:c25:c25:c500:ec88/1282c19:dd:d9:dd:c25:c25:c500:ec88
1382c19:dd:d9:dd:c25:c25:c500:ec89/1282c19:dd:d9:dd:c25:c25:c500:ec89
1392c19:dd:d9:dd:c25:c25:c500:ec8a/1282c19:dd:d9:dd:c25:c25:c500:ec8a
1402c19:dd:d9:dd:c25:c25:c500:ec8b/1282c19:dd:d9:dd:c25:c25:c500:ec8b
1412c19:dd:d9:dd:c25:c25:c500:ec8c/1282c19:dd:d9:dd:c25:c25:c500:ec8c
1422c19:dd:d9:dd:c25:c25:c500:ec8d/1282c19:dd:d9:dd:c25:c25:c500:ec8d
1432c19:dd:d9:dd:c25:c25:c500:ec8e/1282c19:dd:d9:dd:c25:c25:c500:ec8e
1442c19:dd:d9:dd:c25:c25:c500:ec8f/1282c19:dd:d9:dd:c25:c25:c500:ec8f
1452c19:dd:d9:dd:c25:c25:c500:ec90/1282c19:dd:d9:dd:c25:c25:c500:ec90
1462c19:dd:d9:dd:c25:c25:c500:ec91/1282c19:dd:d9:dd:c25:c25:c500:ec91
1472c19:dd:d9:dd:c25:c25:c500:ec92/1282c19:dd:d9:dd:c25:c25:c500:ec92
1482c19:dd:d9:dd:c25:c25:c500:ec93/1282c19:dd:d9:dd:c25:c25:c500:ec93
1492c19:dd:d9:dd:c25:c25:c500:ec94/1282c19:dd:d9:dd:c25:c25:c500:ec94
1502c19:dd:d9:dd:c25:c25:c500:ec95/1282c19:dd:d9:dd:c25:c25:c500:ec95
1512c19:dd:d9:dd:c25:c25:c500:ec96/1282c19:dd:d9:dd:c25:c25:c500:ec96
1522c19:dd:d9:dd:c25:c25:c500:ec97/1282c19:dd:d9:dd:c25:c25:c500:ec97
1532c19:dd:d9:dd:c25:c25:c500:ec98/1282c19:dd:d9:dd:c25:c25:c500:ec98
1542c19:dd:d9:dd:c25:c25:c500:ec99/1282c19:dd:d9:dd:c25:c25:c500:ec99
1552c19:dd:d9:dd:c25:c25:c500:ec9a/1282c19:dd:d9:dd:c25:c25:c500:ec9a
1562c19:dd:d9:dd:c25:c25:c500:ec9b/1282c19:dd:d9:dd:c25:c25:c500:ec9b
1572c19:dd:d9:dd:c25:c25:c500:ec9c/1282c19:dd:d9:dd:c25:c25:c500:ec9c
1582c19:dd:d9:dd:c25:c25:c500:ec9d/1282c19:dd:d9:dd:c25:c25:c500:ec9d
1592c19:dd:d9:dd:c25:c25:c500:ec9e/1282c19:dd:d9:dd:c25:c25:c500:ec9e
1602c19:dd:d9:dd:c25:c25:c500:ec9f/1282c19:dd:d9:dd:c25:c25:c500:ec9f
1612c19:dd:d9:dd:c25:c25:c500:eca0/1282c19:dd:d9:dd:c25:c25:c500:eca0
1622c19:dd:d9:dd:c25:c25:c500:eca1/1282c19:dd:d9:dd:c25:c25:c500:eca1
1632c19:dd:d9:dd:c25:c25:c500:eca2/1282c19:dd:d9:dd:c25:c25:c500:eca2
1642c19:dd:d9:dd:c25:c25:c500:eca3/1282c19:dd:d9:dd:c25:c25:c500:eca3
1652c19:dd:d9:dd:c25:c25:c500:eca4/1282c19:dd:d9:dd:c25:c25:c500:eca4
1662c19:dd:d9:dd:c25:c25:c500:eca5/1282c19:dd:d9:dd:c25:c25:c500:eca5
1672c19:dd:d9:dd:c25:c25:c500:eca6/1282c19:dd:d9:dd:c25:c25:c500:eca6
1682c19:dd:d9:dd:c25:c25:c500:eca7/1282c19:dd:d9:dd:c25:c25:c500:eca7
1692c19:dd:d9:dd:c25:c25:c500:eca8/1282c19:dd:d9:dd:c25:c25:c500:eca8
1702c19:dd:d9:dd:c25:c25:c500:eca9/1282c19:dd:d9:dd:c25:c25:c500:eca9
1712c19:dd:d9:dd:c25:c25:c500:ecaa/1282c19:dd:d9:dd:c25:c25:c500:ecaa
1722c19:dd:d9:dd:c25:c25:c500:ecab/1282c19:dd:d9:dd:c25:c25:c500:ecab
1732c19:dd:d9:dd:c25:c25:c500:ecac/1282c19:dd:d9:dd:c25:c25:c500:ecac
1742c19:dd:d9:dd:c25:c25:c500:ecad/1282c19:dd:d9:dd:c25:c25:c500:ecad
1752c19:dd:d9:dd:c25:c25:c500:ecae/1282c19:dd:d9:dd:c25:c25:c500:ecae
1762c19:dd:d9:dd:c25:c25:c500:ecaf/1282c19:dd:d9:dd:c25:c25:c500:ecaf
1772c19:dd:d9:dd:c25:c25:c500:ecb0/1282c19:dd:d9:dd:c25:c25:c500:ecb0
1782c19:dd:d9:dd:c25:c25:c500:ecb1/1282c19:dd:d9:dd:c25:c25:c500:ecb1
1792c19:dd:d9:dd:c25:c25:c500:ecb2/1282c19:dd:d9:dd:c25:c25:c500:ecb2
1802c19:dd:d9:dd:c25:c25:c500:ecb3/1282c19:dd:d9:dd:c25:c25:c500:ecb3
1812c19:dd:d9:dd:c25:c25:c500:ecb4/1282c19:dd:d9:dd:c25:c25:c500:ecb4
1822c19:dd:d9:dd:c25:c25:c500:ecb5/1282c19:dd:d9:dd:c25:c25:c500:ecb5
1832c19:dd:d9:dd:c25:c25:c500:ecb6/1282c19:dd:d9:dd:c25:c25:c500:ecb6
1842c19:dd:d9:dd:c25:c25:c500:ecb7/1282c19:dd:d9:dd:c25:c25:c500:ecb7
1852c19:dd:d9:dd:c25:c25:c500:ecb8/1282c19:dd:d9:dd:c25:c25:c500:ecb8
1862c19:dd:d9:dd:c25:c25:c500:ecb9/1282c19:dd:d9:dd:c25:c25:c500:ecb9
1872c19:dd:d9:dd:c25:c25:c500:ecba/1282c19:dd:d9:dd:c25:c25:c500:ecba
1882c19:dd:d9:dd:c25:c25:c500:ecbb/1282c19:dd:d9:dd:c25:c25:c500:ecbb
1892c19:dd:d9:dd:c25:c25:c500:ecbc/1282c19:dd:d9:dd:c25:c25:c500:ecbc
1902c19:dd:d9:dd:c25:c25:c500:ecbd/1282c19:dd:d9:dd:c25:c25:c500:ecbd
1912c19:dd:d9:dd:c25:c25:c500:ecbe/1282c19:dd:d9:dd:c25:c25:c500:ecbe
1922c19:dd:d9:dd:c25:c25:c500:ecbf/1282c19:dd:d9:dd:c25:c25:c500:ecbf
1932c19:dd:d9:dd:c25:c25:c500:ecc0/1282c19:dd:d9:dd:c25:c25:c500:ecc0
1942c19:dd:d9:dd:c25:c25:c500:ecc1/1282c19:dd:d9:dd:c25:c25:c500:ecc1
1952c19:dd:d9:dd:c25:c25:c500:ecc2/1282c19:dd:d9:dd:c25:c25:c500:ecc2
1962c19:dd:d9:dd:c25:c25:c500:ecc3/1282c19:dd:d9:dd:c25:c25:c500:ecc3
1972c19:dd:d9:dd:c25:c25:c500:ecc4/1282c19:dd:d9:dd:c25:c25:c500:ecc4
1982c19:dd:d9:dd:c25:c25:c500:ecc5/1282c19:dd:d9:dd:c25:c25:c500:ecc5
1992c19:dd:d9:dd:c25:c25:c500:ecc6/1282c19:dd:d9:dd:c25:c25:c500:ecc6
2002c19:dd:d9:dd:c25:c25:c500:ecc7/1282c19:dd:d9:dd:c25:c25:c500:ecc7
2012c19:dd:d9:dd:c25:c25:c500:ecc8/1282c19:dd:d9:dd:c25:c25:c500:ecc8
2022c19:dd:d9:dd:c25:c25:c500:ecc9/1282c19:dd:d9:dd:c25:c25:c500:ecc9
2032c19:dd:d9:dd:c25:c25:c500:ecca/1282c19:dd:d9:dd:c25:c25:c500:ecca
2042c19:dd:d9:dd:c25:c25:c500:eccb/1282c19:dd:d9:dd:c25:c25:c500:eccb
2052c19:dd:d9:dd:c25:c25:c500:eccc/1282c19:dd:d9:dd:c25:c25:c500:eccc
2062c19:dd:d9:dd:c25:c25:c500:eccd/1282c19:dd:d9:dd:c25:c25:c500:eccd
2072c19:dd:d9:dd:c25:c25:c500:ecce/1282c19:dd:d9:dd:c25:c25:c500:ecce
2082c19:dd:d9:dd:c25:c25:c500:eccf/1282c19:dd:d9:dd:c25:c25:c500:eccf
2092c19:dd:d9:dd:c25:c25:c500:ecd0/1282c19:dd:d9:dd:c25:c25:c500:ecd0
2102c19:dd:d9:dd:c25:c25:c500:ecd1/1282c19:dd:d9:dd:c25:c25:c500:ecd1
2112c19:dd:d9:dd:c25:c25:c500:ecd2/1282c19:dd:d9:dd:c25:c25:c500:ecd2
2122c19:dd:d9:dd:c25:c25:c500:ecd3/1282c19:dd:d9:dd:c25:c25:c500:ecd3
2132c19:dd:d9:dd:c25:c25:c500:ecd4/1282c19:dd:d9:dd:c25:c25:c500:ecd4
2142c19:dd:d9:dd:c25:c25:c500:ecd5/1282c19:dd:d9:dd:c25:c25:c500:ecd5
2152c19:dd:d9:dd:c25:c25:c500:ecd6/1282c19:dd:d9:dd:c25:c25:c500:ecd6
2162c19:dd:d9:dd:c25:c25:c500:ecd7/1282c19:dd:d9:dd:c25:c25:c500:ecd7
2172c19:dd:d9:dd:c25:c25:c500:ecd8/1282c19:dd:d9:dd:c25:c25:c500:ecd8
2182c19:dd:d9:dd:c25:c25:c500:ecd9/1282c19:dd:d9:dd:c25:c25:c500:ecd9
2192c19:dd:d9:dd:c25:c25:c500:ecda/1282c19:dd:d9:dd:c25:c25:c500:ecda
2202c19:dd:d9:dd:c25:c25:c500:ecdb/1282c19:dd:d9:dd:c25:c25:c500:ecdb
2212c19:dd:d9:dd:c25:c25:c500:ecdc/1282c19:dd:d9:dd:c25:c25:c500:ecdc
2222c19:dd:d9:dd:c25:c25:c500:ecdd/1282c19:dd:d9:dd:c25:c25:c500:ecdd
2232c19:dd:d9:dd:c25:c25:c500:ecde/1282c19:dd:d9:dd:c25:c25:c500:ecde
2242c19:dd:d9:dd:c25:c25:c500:ecdf/1282c19:dd:d9:dd:c25:c25:c500:ecdf
2252c19:dd:d9:dd:c25:c25:c500:ece0/1282c19:dd:d9:dd:c25:c25:c500:ece0
2262c19:dd:d9:dd:c25:c25:c500:ece1/1282c19:dd:d9:dd:c25:c25:c500:ece1
2272c19:dd:d9:dd:c25:c25:c500:ece2/1282c19:dd:d9:dd:c25:c25:c500:ece2
2282c19:dd:d9:dd:c25:c25:c500:ece3/1282c19:dd:d9:dd:c25:c25:c500:ece3
2292c19:dd:d9:dd:c25:c25:c500:ece4/1282c19:dd:d9:dd:c25:c25:c500:ece4
2302c19:dd:d9:dd:c25:c25:c500:ece5/1282c19:dd:d9:dd:c25:c25:c500:ece5
2312c19:dd:d9:dd:c25:c25:c500:ece6/1282c19:dd:d9:dd:c25:c25:c500:ece6
2322c19:dd:d9:dd:c25:c25:c500:ece7/1282c19:dd:d9:dd:c25:c25:c500:ece7
2332c19:dd:d9:dd:c25:c25:c500:ece8/1282c19:dd:d9:dd:c25:c25:c500:ece8
2342c19:dd:d9:dd:c25:c25:c500:ece9/1282c19:dd:d9:dd:c25:c25:c500:ece9
2352c19:dd:d9:dd:c25:c25:c500:ecea/1282c19:dd:d9:dd:c25:c25:c500:ecea
2362c19:dd:d9:dd:c25:c25:c500:eceb/1282c19:dd:d9:dd:c25:c25:c500:eceb
2372c19:dd:d9:dd:c25:c25:c500:ecec/1282c19:dd:d9:dd:c25:c25:c500:ecec
2382c19:dd:d9:dd:c25:c25:c500:eced/1282c19:dd:d9:dd:c25:c25:c500:eced
2392c19:dd:d9:dd:c25:c25:c500:ecee/1282c19:dd:d9:dd:c25:c25:c500:ecee
2402c19:dd:d9:dd:c25:c25:c500:ecef/1282c19:dd:d9:dd:c25:c25:c500:ecef
2412c19:dd:d9:dd:c25:c25:c500:ecf0/1282c19:dd:d9:dd:c25:c25:c500:ecf0
2422c19:dd:d9:dd:c25:c25:c500:ecf1/1282c19:dd:d9:dd:c25:c25:c500:ecf1
2432c19:dd:d9:dd:c25:c25:c500:ecf2/1282c19:dd:d9:dd:c25:c25:c500:ecf2
2442c19:dd:d9:dd:c25:c25:c500:ecf3/1282c19:dd:d9:dd:c25:c25:c500:ecf3
2452c19:dd:d9:dd:c25:c25:c500:ecf4/1282c19:dd:d9:dd:c25:c25:c500:ecf4
2462c19:dd:d9:dd:c25:c25:c500:ecf5/1282c19:dd:d9:dd:c25:c25:c500:ecf5
2472c19:dd:d9:dd:c25:c25:c500:ecf6/1282c19:dd:d9:dd:c25:c25:c500:ecf6
2482c19:dd:d9:dd:c25:c25:c500:ecf7/1282c19:dd:d9:dd:c25:c25:c500:ecf7
2492c19:dd:d9:dd:c25:c25:c500:ecf8/1282c19:dd:d9:dd:c25:c25:c500:ecf8
2502c19:dd:d9:dd:c25:c25:c500:ecf9/1282c19:dd:d9:dd:c25:c25:c500:ecf9
2512c19:dd:d9:dd:c25:c25:c500:ecfa/1282c19:dd:d9:dd:c25:c25:c500:ecfa
2522c19:dd:d9:dd:c25:c25:c500:ecfb/1282c19:dd:d9:dd:c25:c25:c500:ecfb
2532c19:dd:d9:dd:c25:c25:c500:ecfc/1282c19:dd:d9:dd:c25:c25:c500:ecfc
2542c19:dd:d9:dd:c25:c25:c500:ecfd/1282c19:dd:d9:dd:c25:c25:c500:ecfd
2552c19:dd:d9:dd:c25:c25:c500:ecfe/1282c19:dd:d9:dd:c25:c25:c500:ecfe
2562c19:dd:d9:dd:c25:c25:c500:ecff/1282c19:dd:d9:dd:c25:c25:c500:ecff

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.