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/119
Addresses512
/64 networksPart of one
Network
2c19:dd:c25:c25d:dd:dd:dd:3e00/119
First address
2c19:dd:c25:c25d:dd:dd:dd:3e00
Last address
2c19:dd:c25:c25d:dd:dd:dd:3fff
Addresses
512
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:0c25:c25d:00dd:00dd:00dd:3e00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
e.3.d.d.0.0.d.d.0.0.d.d.0.0.d.5.2.c.5.2.c.0.d.d.0.0.9.1.c.2.ip6.arpa
f.3.d.d.0.0.d.d.0.0.d.d.0.0.d.5.2.c.5.2.c.0.d.d.0.0.9.1.c.2.ip6.arpa
/119 is not on a 4-bit boundary, so it takes 2 /120 zones.
Split into smaller subnets/128
/120 (2)/121 (4)/122 (8)/123 (16)/124 (32)/127 (256)/128 (512)

2c19:dd:c25:c25d:dd:dd:dd:3e00/119 makes 512 subnets of /128; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:c25:c25d:dd:dd:dd:3e00/1282c19:dd:c25:c25d:dd:dd:dd:3e00
22c19:dd:c25:c25d:dd:dd:dd:3e01/1282c19:dd:c25:c25d:dd:dd:dd:3e01
32c19:dd:c25:c25d:dd:dd:dd:3e02/1282c19:dd:c25:c25d:dd:dd:dd:3e02
42c19:dd:c25:c25d:dd:dd:dd:3e03/1282c19:dd:c25:c25d:dd:dd:dd:3e03
52c19:dd:c25:c25d:dd:dd:dd:3e04/1282c19:dd:c25:c25d:dd:dd:dd:3e04
62c19:dd:c25:c25d:dd:dd:dd:3e05/1282c19:dd:c25:c25d:dd:dd:dd:3e05
72c19:dd:c25:c25d:dd:dd:dd:3e06/1282c19:dd:c25:c25d:dd:dd:dd:3e06
82c19:dd:c25:c25d:dd:dd:dd:3e07/1282c19:dd:c25:c25d:dd:dd:dd:3e07
92c19:dd:c25:c25d:dd:dd:dd:3e08/1282c19:dd:c25:c25d:dd:dd:dd:3e08
102c19:dd:c25:c25d:dd:dd:dd:3e09/1282c19:dd:c25:c25d:dd:dd:dd:3e09
112c19:dd:c25:c25d:dd:dd:dd:3e0a/1282c19:dd:c25:c25d:dd:dd:dd:3e0a
122c19:dd:c25:c25d:dd:dd:dd:3e0b/1282c19:dd:c25:c25d:dd:dd:dd:3e0b
132c19:dd:c25:c25d:dd:dd:dd:3e0c/1282c19:dd:c25:c25d:dd:dd:dd:3e0c
142c19:dd:c25:c25d:dd:dd:dd:3e0d/1282c19:dd:c25:c25d:dd:dd:dd:3e0d
152c19:dd:c25:c25d:dd:dd:dd:3e0e/1282c19:dd:c25:c25d:dd:dd:dd:3e0e
162c19:dd:c25:c25d:dd:dd:dd:3e0f/1282c19:dd:c25:c25d:dd:dd:dd:3e0f
172c19:dd:c25:c25d:dd:dd:dd:3e10/1282c19:dd:c25:c25d:dd:dd:dd:3e10
182c19:dd:c25:c25d:dd:dd:dd:3e11/1282c19:dd:c25:c25d:dd:dd:dd:3e11
192c19:dd:c25:c25d:dd:dd:dd:3e12/1282c19:dd:c25:c25d:dd:dd:dd:3e12
202c19:dd:c25:c25d:dd:dd:dd:3e13/1282c19:dd:c25:c25d:dd:dd:dd:3e13
212c19:dd:c25:c25d:dd:dd:dd:3e14/1282c19:dd:c25:c25d:dd:dd:dd:3e14
222c19:dd:c25:c25d:dd:dd:dd:3e15/1282c19:dd:c25:c25d:dd:dd:dd:3e15
232c19:dd:c25:c25d:dd:dd:dd:3e16/1282c19:dd:c25:c25d:dd:dd:dd:3e16
242c19:dd:c25:c25d:dd:dd:dd:3e17/1282c19:dd:c25:c25d:dd:dd:dd:3e17
252c19:dd:c25:c25d:dd:dd:dd:3e18/1282c19:dd:c25:c25d:dd:dd:dd:3e18
262c19:dd:c25:c25d:dd:dd:dd:3e19/1282c19:dd:c25:c25d:dd:dd:dd:3e19
272c19:dd:c25:c25d:dd:dd:dd:3e1a/1282c19:dd:c25:c25d:dd:dd:dd:3e1a
282c19:dd:c25:c25d:dd:dd:dd:3e1b/1282c19:dd:c25:c25d:dd:dd:dd:3e1b
292c19:dd:c25:c25d:dd:dd:dd:3e1c/1282c19:dd:c25:c25d:dd:dd:dd:3e1c
302c19:dd:c25:c25d:dd:dd:dd:3e1d/1282c19:dd:c25:c25d:dd:dd:dd:3e1d
312c19:dd:c25:c25d:dd:dd:dd:3e1e/1282c19:dd:c25:c25d:dd:dd:dd:3e1e
322c19:dd:c25:c25d:dd:dd:dd:3e1f/1282c19:dd:c25:c25d:dd:dd:dd:3e1f
332c19:dd:c25:c25d:dd:dd:dd:3e20/1282c19:dd:c25:c25d:dd:dd:dd:3e20
342c19:dd:c25:c25d:dd:dd:dd:3e21/1282c19:dd:c25:c25d:dd:dd:dd:3e21
352c19:dd:c25:c25d:dd:dd:dd:3e22/1282c19:dd:c25:c25d:dd:dd:dd:3e22
362c19:dd:c25:c25d:dd:dd:dd:3e23/1282c19:dd:c25:c25d:dd:dd:dd:3e23
372c19:dd:c25:c25d:dd:dd:dd:3e24/1282c19:dd:c25:c25d:dd:dd:dd:3e24
382c19:dd:c25:c25d:dd:dd:dd:3e25/1282c19:dd:c25:c25d:dd:dd:dd:3e25
392c19:dd:c25:c25d:dd:dd:dd:3e26/1282c19:dd:c25:c25d:dd:dd:dd:3e26
402c19:dd:c25:c25d:dd:dd:dd:3e27/1282c19:dd:c25:c25d:dd:dd:dd:3e27
412c19:dd:c25:c25d:dd:dd:dd:3e28/1282c19:dd:c25:c25d:dd:dd:dd:3e28
422c19:dd:c25:c25d:dd:dd:dd:3e29/1282c19:dd:c25:c25d:dd:dd:dd:3e29
432c19:dd:c25:c25d:dd:dd:dd:3e2a/1282c19:dd:c25:c25d:dd:dd:dd:3e2a
442c19:dd:c25:c25d:dd:dd:dd:3e2b/1282c19:dd:c25:c25d:dd:dd:dd:3e2b
452c19:dd:c25:c25d:dd:dd:dd:3e2c/1282c19:dd:c25:c25d:dd:dd:dd:3e2c
462c19:dd:c25:c25d:dd:dd:dd:3e2d/1282c19:dd:c25:c25d:dd:dd:dd:3e2d
472c19:dd:c25:c25d:dd:dd:dd:3e2e/1282c19:dd:c25:c25d:dd:dd:dd:3e2e
482c19:dd:c25:c25d:dd:dd:dd:3e2f/1282c19:dd:c25:c25d:dd:dd:dd:3e2f
492c19:dd:c25:c25d:dd:dd:dd:3e30/1282c19:dd:c25:c25d:dd:dd:dd:3e30
502c19:dd:c25:c25d:dd:dd:dd:3e31/1282c19:dd:c25:c25d:dd:dd:dd:3e31
512c19:dd:c25:c25d:dd:dd:dd:3e32/1282c19:dd:c25:c25d:dd:dd:dd:3e32
522c19:dd:c25:c25d:dd:dd:dd:3e33/1282c19:dd:c25:c25d:dd:dd:dd:3e33
532c19:dd:c25:c25d:dd:dd:dd:3e34/1282c19:dd:c25:c25d:dd:dd:dd:3e34
542c19:dd:c25:c25d:dd:dd:dd:3e35/1282c19:dd:c25:c25d:dd:dd:dd:3e35
552c19:dd:c25:c25d:dd:dd:dd:3e36/1282c19:dd:c25:c25d:dd:dd:dd:3e36
562c19:dd:c25:c25d:dd:dd:dd:3e37/1282c19:dd:c25:c25d:dd:dd:dd:3e37
572c19:dd:c25:c25d:dd:dd:dd:3e38/1282c19:dd:c25:c25d:dd:dd:dd:3e38
582c19:dd:c25:c25d:dd:dd:dd:3e39/1282c19:dd:c25:c25d:dd:dd:dd:3e39
592c19:dd:c25:c25d:dd:dd:dd:3e3a/1282c19:dd:c25:c25d:dd:dd:dd:3e3a
602c19:dd:c25:c25d:dd:dd:dd:3e3b/1282c19:dd:c25:c25d:dd:dd:dd:3e3b
612c19:dd:c25:c25d:dd:dd:dd:3e3c/1282c19:dd:c25:c25d:dd:dd:dd:3e3c
622c19:dd:c25:c25d:dd:dd:dd:3e3d/1282c19:dd:c25:c25d:dd:dd:dd:3e3d
632c19:dd:c25:c25d:dd:dd:dd:3e3e/1282c19:dd:c25:c25d:dd:dd:dd:3e3e
642c19:dd:c25:c25d:dd:dd:dd:3e3f/1282c19:dd:c25:c25d:dd:dd:dd:3e3f
652c19:dd:c25:c25d:dd:dd:dd:3e40/1282c19:dd:c25:c25d:dd:dd:dd:3e40
662c19:dd:c25:c25d:dd:dd:dd:3e41/1282c19:dd:c25:c25d:dd:dd:dd:3e41
672c19:dd:c25:c25d:dd:dd:dd:3e42/1282c19:dd:c25:c25d:dd:dd:dd:3e42
682c19:dd:c25:c25d:dd:dd:dd:3e43/1282c19:dd:c25:c25d:dd:dd:dd:3e43
692c19:dd:c25:c25d:dd:dd:dd:3e44/1282c19:dd:c25:c25d:dd:dd:dd:3e44
702c19:dd:c25:c25d:dd:dd:dd:3e45/1282c19:dd:c25:c25d:dd:dd:dd:3e45
712c19:dd:c25:c25d:dd:dd:dd:3e46/1282c19:dd:c25:c25d:dd:dd:dd:3e46
722c19:dd:c25:c25d:dd:dd:dd:3e47/1282c19:dd:c25:c25d:dd:dd:dd:3e47
732c19:dd:c25:c25d:dd:dd:dd:3e48/1282c19:dd:c25:c25d:dd:dd:dd:3e48
742c19:dd:c25:c25d:dd:dd:dd:3e49/1282c19:dd:c25:c25d:dd:dd:dd:3e49
752c19:dd:c25:c25d:dd:dd:dd:3e4a/1282c19:dd:c25:c25d:dd:dd:dd:3e4a
762c19:dd:c25:c25d:dd:dd:dd:3e4b/1282c19:dd:c25:c25d:dd:dd:dd:3e4b
772c19:dd:c25:c25d:dd:dd:dd:3e4c/1282c19:dd:c25:c25d:dd:dd:dd:3e4c
782c19:dd:c25:c25d:dd:dd:dd:3e4d/1282c19:dd:c25:c25d:dd:dd:dd:3e4d
792c19:dd:c25:c25d:dd:dd:dd:3e4e/1282c19:dd:c25:c25d:dd:dd:dd:3e4e
802c19:dd:c25:c25d:dd:dd:dd:3e4f/1282c19:dd:c25:c25d:dd:dd:dd:3e4f
812c19:dd:c25:c25d:dd:dd:dd:3e50/1282c19:dd:c25:c25d:dd:dd:dd:3e50
822c19:dd:c25:c25d:dd:dd:dd:3e51/1282c19:dd:c25:c25d:dd:dd:dd:3e51
832c19:dd:c25:c25d:dd:dd:dd:3e52/1282c19:dd:c25:c25d:dd:dd:dd:3e52
842c19:dd:c25:c25d:dd:dd:dd:3e53/1282c19:dd:c25:c25d:dd:dd:dd:3e53
852c19:dd:c25:c25d:dd:dd:dd:3e54/1282c19:dd:c25:c25d:dd:dd:dd:3e54
862c19:dd:c25:c25d:dd:dd:dd:3e55/1282c19:dd:c25:c25d:dd:dd:dd:3e55
872c19:dd:c25:c25d:dd:dd:dd:3e56/1282c19:dd:c25:c25d:dd:dd:dd:3e56
882c19:dd:c25:c25d:dd:dd:dd:3e57/1282c19:dd:c25:c25d:dd:dd:dd:3e57
892c19:dd:c25:c25d:dd:dd:dd:3e58/1282c19:dd:c25:c25d:dd:dd:dd:3e58
902c19:dd:c25:c25d:dd:dd:dd:3e59/1282c19:dd:c25:c25d:dd:dd:dd:3e59
912c19:dd:c25:c25d:dd:dd:dd:3e5a/1282c19:dd:c25:c25d:dd:dd:dd:3e5a
922c19:dd:c25:c25d:dd:dd:dd:3e5b/1282c19:dd:c25:c25d:dd:dd:dd:3e5b
932c19:dd:c25:c25d:dd:dd:dd:3e5c/1282c19:dd:c25:c25d:dd:dd:dd:3e5c
942c19:dd:c25:c25d:dd:dd:dd:3e5d/1282c19:dd:c25:c25d:dd:dd:dd:3e5d
952c19:dd:c25:c25d:dd:dd:dd:3e5e/1282c19:dd:c25:c25d:dd:dd:dd:3e5e
962c19:dd:c25:c25d:dd:dd:dd:3e5f/1282c19:dd:c25:c25d:dd:dd:dd:3e5f
972c19:dd:c25:c25d:dd:dd:dd:3e60/1282c19:dd:c25:c25d:dd:dd:dd:3e60
982c19:dd:c25:c25d:dd:dd:dd:3e61/1282c19:dd:c25:c25d:dd:dd:dd:3e61
992c19:dd:c25:c25d:dd:dd:dd:3e62/1282c19:dd:c25:c25d:dd:dd:dd:3e62
1002c19:dd:c25:c25d:dd:dd:dd:3e63/1282c19:dd:c25:c25d:dd:dd:dd:3e63
1012c19:dd:c25:c25d:dd:dd:dd:3e64/1282c19:dd:c25:c25d:dd:dd:dd:3e64
1022c19:dd:c25:c25d:dd:dd:dd:3e65/1282c19:dd:c25:c25d:dd:dd:dd:3e65
1032c19:dd:c25:c25d:dd:dd:dd:3e66/1282c19:dd:c25:c25d:dd:dd:dd:3e66
1042c19:dd:c25:c25d:dd:dd:dd:3e67/1282c19:dd:c25:c25d:dd:dd:dd:3e67
1052c19:dd:c25:c25d:dd:dd:dd:3e68/1282c19:dd:c25:c25d:dd:dd:dd:3e68
1062c19:dd:c25:c25d:dd:dd:dd:3e69/1282c19:dd:c25:c25d:dd:dd:dd:3e69
1072c19:dd:c25:c25d:dd:dd:dd:3e6a/1282c19:dd:c25:c25d:dd:dd:dd:3e6a
1082c19:dd:c25:c25d:dd:dd:dd:3e6b/1282c19:dd:c25:c25d:dd:dd:dd:3e6b
1092c19:dd:c25:c25d:dd:dd:dd:3e6c/1282c19:dd:c25:c25d:dd:dd:dd:3e6c
1102c19:dd:c25:c25d:dd:dd:dd:3e6d/1282c19:dd:c25:c25d:dd:dd:dd:3e6d
1112c19:dd:c25:c25d:dd:dd:dd:3e6e/1282c19:dd:c25:c25d:dd:dd:dd:3e6e
1122c19:dd:c25:c25d:dd:dd:dd:3e6f/1282c19:dd:c25:c25d:dd:dd:dd:3e6f
1132c19:dd:c25:c25d:dd:dd:dd:3e70/1282c19:dd:c25:c25d:dd:dd:dd:3e70
1142c19:dd:c25:c25d:dd:dd:dd:3e71/1282c19:dd:c25:c25d:dd:dd:dd:3e71
1152c19:dd:c25:c25d:dd:dd:dd:3e72/1282c19:dd:c25:c25d:dd:dd:dd:3e72
1162c19:dd:c25:c25d:dd:dd:dd:3e73/1282c19:dd:c25:c25d:dd:dd:dd:3e73
1172c19:dd:c25:c25d:dd:dd:dd:3e74/1282c19:dd:c25:c25d:dd:dd:dd:3e74
1182c19:dd:c25:c25d:dd:dd:dd:3e75/1282c19:dd:c25:c25d:dd:dd:dd:3e75
1192c19:dd:c25:c25d:dd:dd:dd:3e76/1282c19:dd:c25:c25d:dd:dd:dd:3e76
1202c19:dd:c25:c25d:dd:dd:dd:3e77/1282c19:dd:c25:c25d:dd:dd:dd:3e77
1212c19:dd:c25:c25d:dd:dd:dd:3e78/1282c19:dd:c25:c25d:dd:dd:dd:3e78
1222c19:dd:c25:c25d:dd:dd:dd:3e79/1282c19:dd:c25:c25d:dd:dd:dd:3e79
1232c19:dd:c25:c25d:dd:dd:dd:3e7a/1282c19:dd:c25:c25d:dd:dd:dd:3e7a
1242c19:dd:c25:c25d:dd:dd:dd:3e7b/1282c19:dd:c25:c25d:dd:dd:dd:3e7b
1252c19:dd:c25:c25d:dd:dd:dd:3e7c/1282c19:dd:c25:c25d:dd:dd:dd:3e7c
1262c19:dd:c25:c25d:dd:dd:dd:3e7d/1282c19:dd:c25:c25d:dd:dd:dd:3e7d
1272c19:dd:c25:c25d:dd:dd:dd:3e7e/1282c19:dd:c25:c25d:dd:dd:dd:3e7e
1282c19:dd:c25:c25d:dd:dd:dd:3e7f/1282c19:dd:c25:c25d:dd:dd:dd:3e7f
1292c19:dd:c25:c25d:dd:dd:dd:3e80/1282c19:dd:c25:c25d:dd:dd:dd:3e80
1302c19:dd:c25:c25d:dd:dd:dd:3e81/1282c19:dd:c25:c25d:dd:dd:dd:3e81
1312c19:dd:c25:c25d:dd:dd:dd:3e82/1282c19:dd:c25:c25d:dd:dd:dd:3e82
1322c19:dd:c25:c25d:dd:dd:dd:3e83/1282c19:dd:c25:c25d:dd:dd:dd:3e83
1332c19:dd:c25:c25d:dd:dd:dd:3e84/1282c19:dd:c25:c25d:dd:dd:dd:3e84
1342c19:dd:c25:c25d:dd:dd:dd:3e85/1282c19:dd:c25:c25d:dd:dd:dd:3e85
1352c19:dd:c25:c25d:dd:dd:dd:3e86/1282c19:dd:c25:c25d:dd:dd:dd:3e86
1362c19:dd:c25:c25d:dd:dd:dd:3e87/1282c19:dd:c25:c25d:dd:dd:dd:3e87
1372c19:dd:c25:c25d:dd:dd:dd:3e88/1282c19:dd:c25:c25d:dd:dd:dd:3e88
1382c19:dd:c25:c25d:dd:dd:dd:3e89/1282c19:dd:c25:c25d:dd:dd:dd:3e89
1392c19:dd:c25:c25d:dd:dd:dd:3e8a/1282c19:dd:c25:c25d:dd:dd:dd:3e8a
1402c19:dd:c25:c25d:dd:dd:dd:3e8b/1282c19:dd:c25:c25d:dd:dd:dd:3e8b
1412c19:dd:c25:c25d:dd:dd:dd:3e8c/1282c19:dd:c25:c25d:dd:dd:dd:3e8c
1422c19:dd:c25:c25d:dd:dd:dd:3e8d/1282c19:dd:c25:c25d:dd:dd:dd:3e8d
1432c19:dd:c25:c25d:dd:dd:dd:3e8e/1282c19:dd:c25:c25d:dd:dd:dd:3e8e
1442c19:dd:c25:c25d:dd:dd:dd:3e8f/1282c19:dd:c25:c25d:dd:dd:dd:3e8f
1452c19:dd:c25:c25d:dd:dd:dd:3e90/1282c19:dd:c25:c25d:dd:dd:dd:3e90
1462c19:dd:c25:c25d:dd:dd:dd:3e91/1282c19:dd:c25:c25d:dd:dd:dd:3e91
1472c19:dd:c25:c25d:dd:dd:dd:3e92/1282c19:dd:c25:c25d:dd:dd:dd:3e92
1482c19:dd:c25:c25d:dd:dd:dd:3e93/1282c19:dd:c25:c25d:dd:dd:dd:3e93
1492c19:dd:c25:c25d:dd:dd:dd:3e94/1282c19:dd:c25:c25d:dd:dd:dd:3e94
1502c19:dd:c25:c25d:dd:dd:dd:3e95/1282c19:dd:c25:c25d:dd:dd:dd:3e95
1512c19:dd:c25:c25d:dd:dd:dd:3e96/1282c19:dd:c25:c25d:dd:dd:dd:3e96
1522c19:dd:c25:c25d:dd:dd:dd:3e97/1282c19:dd:c25:c25d:dd:dd:dd:3e97
1532c19:dd:c25:c25d:dd:dd:dd:3e98/1282c19:dd:c25:c25d:dd:dd:dd:3e98
1542c19:dd:c25:c25d:dd:dd:dd:3e99/1282c19:dd:c25:c25d:dd:dd:dd:3e99
1552c19:dd:c25:c25d:dd:dd:dd:3e9a/1282c19:dd:c25:c25d:dd:dd:dd:3e9a
1562c19:dd:c25:c25d:dd:dd:dd:3e9b/1282c19:dd:c25:c25d:dd:dd:dd:3e9b
1572c19:dd:c25:c25d:dd:dd:dd:3e9c/1282c19:dd:c25:c25d:dd:dd:dd:3e9c
1582c19:dd:c25:c25d:dd:dd:dd:3e9d/1282c19:dd:c25:c25d:dd:dd:dd:3e9d
1592c19:dd:c25:c25d:dd:dd:dd:3e9e/1282c19:dd:c25:c25d:dd:dd:dd:3e9e
1602c19:dd:c25:c25d:dd:dd:dd:3e9f/1282c19:dd:c25:c25d:dd:dd:dd:3e9f
1612c19:dd:c25:c25d:dd:dd:dd:3ea0/1282c19:dd:c25:c25d:dd:dd:dd:3ea0
1622c19:dd:c25:c25d:dd:dd:dd:3ea1/1282c19:dd:c25:c25d:dd:dd:dd:3ea1
1632c19:dd:c25:c25d:dd:dd:dd:3ea2/1282c19:dd:c25:c25d:dd:dd:dd:3ea2
1642c19:dd:c25:c25d:dd:dd:dd:3ea3/1282c19:dd:c25:c25d:dd:dd:dd:3ea3
1652c19:dd:c25:c25d:dd:dd:dd:3ea4/1282c19:dd:c25:c25d:dd:dd:dd:3ea4
1662c19:dd:c25:c25d:dd:dd:dd:3ea5/1282c19:dd:c25:c25d:dd:dd:dd:3ea5
1672c19:dd:c25:c25d:dd:dd:dd:3ea6/1282c19:dd:c25:c25d:dd:dd:dd:3ea6
1682c19:dd:c25:c25d:dd:dd:dd:3ea7/1282c19:dd:c25:c25d:dd:dd:dd:3ea7
1692c19:dd:c25:c25d:dd:dd:dd:3ea8/1282c19:dd:c25:c25d:dd:dd:dd:3ea8
1702c19:dd:c25:c25d:dd:dd:dd:3ea9/1282c19:dd:c25:c25d:dd:dd:dd:3ea9
1712c19:dd:c25:c25d:dd:dd:dd:3eaa/1282c19:dd:c25:c25d:dd:dd:dd:3eaa
1722c19:dd:c25:c25d:dd:dd:dd:3eab/1282c19:dd:c25:c25d:dd:dd:dd:3eab
1732c19:dd:c25:c25d:dd:dd:dd:3eac/1282c19:dd:c25:c25d:dd:dd:dd:3eac
1742c19:dd:c25:c25d:dd:dd:dd:3ead/1282c19:dd:c25:c25d:dd:dd:dd:3ead
1752c19:dd:c25:c25d:dd:dd:dd:3eae/1282c19:dd:c25:c25d:dd:dd:dd:3eae
1762c19:dd:c25:c25d:dd:dd:dd:3eaf/1282c19:dd:c25:c25d:dd:dd:dd:3eaf
1772c19:dd:c25:c25d:dd:dd:dd:3eb0/1282c19:dd:c25:c25d:dd:dd:dd:3eb0
1782c19:dd:c25:c25d:dd:dd:dd:3eb1/1282c19:dd:c25:c25d:dd:dd:dd:3eb1
1792c19:dd:c25:c25d:dd:dd:dd:3eb2/1282c19:dd:c25:c25d:dd:dd:dd:3eb2
1802c19:dd:c25:c25d:dd:dd:dd:3eb3/1282c19:dd:c25:c25d:dd:dd:dd:3eb3
1812c19:dd:c25:c25d:dd:dd:dd:3eb4/1282c19:dd:c25:c25d:dd:dd:dd:3eb4
1822c19:dd:c25:c25d:dd:dd:dd:3eb5/1282c19:dd:c25:c25d:dd:dd:dd:3eb5
1832c19:dd:c25:c25d:dd:dd:dd:3eb6/1282c19:dd:c25:c25d:dd:dd:dd:3eb6
1842c19:dd:c25:c25d:dd:dd:dd:3eb7/1282c19:dd:c25:c25d:dd:dd:dd:3eb7
1852c19:dd:c25:c25d:dd:dd:dd:3eb8/1282c19:dd:c25:c25d:dd:dd:dd:3eb8
1862c19:dd:c25:c25d:dd:dd:dd:3eb9/1282c19:dd:c25:c25d:dd:dd:dd:3eb9
1872c19:dd:c25:c25d:dd:dd:dd:3eba/1282c19:dd:c25:c25d:dd:dd:dd:3eba
1882c19:dd:c25:c25d:dd:dd:dd:3ebb/1282c19:dd:c25:c25d:dd:dd:dd:3ebb
1892c19:dd:c25:c25d:dd:dd:dd:3ebc/1282c19:dd:c25:c25d:dd:dd:dd:3ebc
1902c19:dd:c25:c25d:dd:dd:dd:3ebd/1282c19:dd:c25:c25d:dd:dd:dd:3ebd
1912c19:dd:c25:c25d:dd:dd:dd:3ebe/1282c19:dd:c25:c25d:dd:dd:dd:3ebe
1922c19:dd:c25:c25d:dd:dd:dd:3ebf/1282c19:dd:c25:c25d:dd:dd:dd:3ebf
1932c19:dd:c25:c25d:dd:dd:dd:3ec0/1282c19:dd:c25:c25d:dd:dd:dd:3ec0
1942c19:dd:c25:c25d:dd:dd:dd:3ec1/1282c19:dd:c25:c25d:dd:dd:dd:3ec1
1952c19:dd:c25:c25d:dd:dd:dd:3ec2/1282c19:dd:c25:c25d:dd:dd:dd:3ec2
1962c19:dd:c25:c25d:dd:dd:dd:3ec3/1282c19:dd:c25:c25d:dd:dd:dd:3ec3
1972c19:dd:c25:c25d:dd:dd:dd:3ec4/1282c19:dd:c25:c25d:dd:dd:dd:3ec4
1982c19:dd:c25:c25d:dd:dd:dd:3ec5/1282c19:dd:c25:c25d:dd:dd:dd:3ec5
1992c19:dd:c25:c25d:dd:dd:dd:3ec6/1282c19:dd:c25:c25d:dd:dd:dd:3ec6
2002c19:dd:c25:c25d:dd:dd:dd:3ec7/1282c19:dd:c25:c25d:dd:dd:dd:3ec7
2012c19:dd:c25:c25d:dd:dd:dd:3ec8/1282c19:dd:c25:c25d:dd:dd:dd:3ec8
2022c19:dd:c25:c25d:dd:dd:dd:3ec9/1282c19:dd:c25:c25d:dd:dd:dd:3ec9
2032c19:dd:c25:c25d:dd:dd:dd:3eca/1282c19:dd:c25:c25d:dd:dd:dd:3eca
2042c19:dd:c25:c25d:dd:dd:dd:3ecb/1282c19:dd:c25:c25d:dd:dd:dd:3ecb
2052c19:dd:c25:c25d:dd:dd:dd:3ecc/1282c19:dd:c25:c25d:dd:dd:dd:3ecc
2062c19:dd:c25:c25d:dd:dd:dd:3ecd/1282c19:dd:c25:c25d:dd:dd:dd:3ecd
2072c19:dd:c25:c25d:dd:dd:dd:3ece/1282c19:dd:c25:c25d:dd:dd:dd:3ece
2082c19:dd:c25:c25d:dd:dd:dd:3ecf/1282c19:dd:c25:c25d:dd:dd:dd:3ecf
2092c19:dd:c25:c25d:dd:dd:dd:3ed0/1282c19:dd:c25:c25d:dd:dd:dd:3ed0
2102c19:dd:c25:c25d:dd:dd:dd:3ed1/1282c19:dd:c25:c25d:dd:dd:dd:3ed1
2112c19:dd:c25:c25d:dd:dd:dd:3ed2/1282c19:dd:c25:c25d:dd:dd:dd:3ed2
2122c19:dd:c25:c25d:dd:dd:dd:3ed3/1282c19:dd:c25:c25d:dd:dd:dd:3ed3
2132c19:dd:c25:c25d:dd:dd:dd:3ed4/1282c19:dd:c25:c25d:dd:dd:dd:3ed4
2142c19:dd:c25:c25d:dd:dd:dd:3ed5/1282c19:dd:c25:c25d:dd:dd:dd:3ed5
2152c19:dd:c25:c25d:dd:dd:dd:3ed6/1282c19:dd:c25:c25d:dd:dd:dd:3ed6
2162c19:dd:c25:c25d:dd:dd:dd:3ed7/1282c19:dd:c25:c25d:dd:dd:dd:3ed7
2172c19:dd:c25:c25d:dd:dd:dd:3ed8/1282c19:dd:c25:c25d:dd:dd:dd:3ed8
2182c19:dd:c25:c25d:dd:dd:dd:3ed9/1282c19:dd:c25:c25d:dd:dd:dd:3ed9
2192c19:dd:c25:c25d:dd:dd:dd:3eda/1282c19:dd:c25:c25d:dd:dd:dd:3eda
2202c19:dd:c25:c25d:dd:dd:dd:3edb/1282c19:dd:c25:c25d:dd:dd:dd:3edb
2212c19:dd:c25:c25d:dd:dd:dd:3edc/1282c19:dd:c25:c25d:dd:dd:dd:3edc
2222c19:dd:c25:c25d:dd:dd:dd:3edd/1282c19:dd:c25:c25d:dd:dd:dd:3edd
2232c19:dd:c25:c25d:dd:dd:dd:3ede/1282c19:dd:c25:c25d:dd:dd:dd:3ede
2242c19:dd:c25:c25d:dd:dd:dd:3edf/1282c19:dd:c25:c25d:dd:dd:dd:3edf
2252c19:dd:c25:c25d:dd:dd:dd:3ee0/1282c19:dd:c25:c25d:dd:dd:dd:3ee0
2262c19:dd:c25:c25d:dd:dd:dd:3ee1/1282c19:dd:c25:c25d:dd:dd:dd:3ee1
2272c19:dd:c25:c25d:dd:dd:dd:3ee2/1282c19:dd:c25:c25d:dd:dd:dd:3ee2
2282c19:dd:c25:c25d:dd:dd:dd:3ee3/1282c19:dd:c25:c25d:dd:dd:dd:3ee3
2292c19:dd:c25:c25d:dd:dd:dd:3ee4/1282c19:dd:c25:c25d:dd:dd:dd:3ee4
2302c19:dd:c25:c25d:dd:dd:dd:3ee5/1282c19:dd:c25:c25d:dd:dd:dd:3ee5
2312c19:dd:c25:c25d:dd:dd:dd:3ee6/1282c19:dd:c25:c25d:dd:dd:dd:3ee6
2322c19:dd:c25:c25d:dd:dd:dd:3ee7/1282c19:dd:c25:c25d:dd:dd:dd:3ee7
2332c19:dd:c25:c25d:dd:dd:dd:3ee8/1282c19:dd:c25:c25d:dd:dd:dd:3ee8
2342c19:dd:c25:c25d:dd:dd:dd:3ee9/1282c19:dd:c25:c25d:dd:dd:dd:3ee9
2352c19:dd:c25:c25d:dd:dd:dd:3eea/1282c19:dd:c25:c25d:dd:dd:dd:3eea
2362c19:dd:c25:c25d:dd:dd:dd:3eeb/1282c19:dd:c25:c25d:dd:dd:dd:3eeb
2372c19:dd:c25:c25d:dd:dd:dd:3eec/1282c19:dd:c25:c25d:dd:dd:dd:3eec
2382c19:dd:c25:c25d:dd:dd:dd:3eed/1282c19:dd:c25:c25d:dd:dd:dd:3eed
2392c19:dd:c25:c25d:dd:dd:dd:3eee/1282c19:dd:c25:c25d:dd:dd:dd:3eee
2402c19:dd:c25:c25d:dd:dd:dd:3eef/1282c19:dd:c25:c25d:dd:dd:dd:3eef
2412c19:dd:c25:c25d:dd:dd:dd:3ef0/1282c19:dd:c25:c25d:dd:dd:dd:3ef0
2422c19:dd:c25:c25d:dd:dd:dd:3ef1/1282c19:dd:c25:c25d:dd:dd:dd:3ef1
2432c19:dd:c25:c25d:dd:dd:dd:3ef2/1282c19:dd:c25:c25d:dd:dd:dd:3ef2
2442c19:dd:c25:c25d:dd:dd:dd:3ef3/1282c19:dd:c25:c25d:dd:dd:dd:3ef3
2452c19:dd:c25:c25d:dd:dd:dd:3ef4/1282c19:dd:c25:c25d:dd:dd:dd:3ef4
2462c19:dd:c25:c25d:dd:dd:dd:3ef5/1282c19:dd:c25:c25d:dd:dd:dd:3ef5
2472c19:dd:c25:c25d:dd:dd:dd:3ef6/1282c19:dd:c25:c25d:dd:dd:dd:3ef6
2482c19:dd:c25:c25d:dd:dd:dd:3ef7/1282c19:dd:c25:c25d:dd:dd:dd:3ef7
2492c19:dd:c25:c25d:dd:dd:dd:3ef8/1282c19:dd:c25:c25d:dd:dd:dd:3ef8
2502c19:dd:c25:c25d:dd:dd:dd:3ef9/1282c19:dd:c25:c25d:dd:dd:dd:3ef9
2512c19:dd:c25:c25d:dd:dd:dd:3efa/1282c19:dd:c25:c25d:dd:dd:dd:3efa
2522c19:dd:c25:c25d:dd:dd:dd:3efb/1282c19:dd:c25:c25d:dd:dd:dd:3efb
2532c19:dd:c25:c25d:dd:dd:dd:3efc/1282c19:dd:c25:c25d:dd:dd:dd:3efc
2542c19:dd:c25:c25d:dd:dd:dd:3efd/1282c19:dd:c25:c25d:dd:dd:dd:3efd
2552c19:dd:c25:c25d:dd:dd:dd:3efe/1282c19:dd:c25:c25d:dd:dd:dd:3efe
2562c19:dd:c25:c25d:dd:dd:dd:3eff/1282c19:dd:c25:c25d:dd:dd:dd:3eff

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.