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:c25:94de:5c00/120
First address
2c19:dd:d9:dd:c25:c25:94de:5c00
Last address
2c19:dd:d9:dd:c25:c25:94de:5cff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:94de:5c00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
c.5.e.d.4.9.5.2.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:c25:94de:5c00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:94de:5c00/1282c19:dd:d9:dd:c25:c25:94de:5c00
22c19:dd:d9:dd:c25:c25:94de:5c01/1282c19:dd:d9:dd:c25:c25:94de:5c01
32c19:dd:d9:dd:c25:c25:94de:5c02/1282c19:dd:d9:dd:c25:c25:94de:5c02
42c19:dd:d9:dd:c25:c25:94de:5c03/1282c19:dd:d9:dd:c25:c25:94de:5c03
52c19:dd:d9:dd:c25:c25:94de:5c04/1282c19:dd:d9:dd:c25:c25:94de:5c04
62c19:dd:d9:dd:c25:c25:94de:5c05/1282c19:dd:d9:dd:c25:c25:94de:5c05
72c19:dd:d9:dd:c25:c25:94de:5c06/1282c19:dd:d9:dd:c25:c25:94de:5c06
82c19:dd:d9:dd:c25:c25:94de:5c07/1282c19:dd:d9:dd:c25:c25:94de:5c07
92c19:dd:d9:dd:c25:c25:94de:5c08/1282c19:dd:d9:dd:c25:c25:94de:5c08
102c19:dd:d9:dd:c25:c25:94de:5c09/1282c19:dd:d9:dd:c25:c25:94de:5c09
112c19:dd:d9:dd:c25:c25:94de:5c0a/1282c19:dd:d9:dd:c25:c25:94de:5c0a
122c19:dd:d9:dd:c25:c25:94de:5c0b/1282c19:dd:d9:dd:c25:c25:94de:5c0b
132c19:dd:d9:dd:c25:c25:94de:5c0c/1282c19:dd:d9:dd:c25:c25:94de:5c0c
142c19:dd:d9:dd:c25:c25:94de:5c0d/1282c19:dd:d9:dd:c25:c25:94de:5c0d
152c19:dd:d9:dd:c25:c25:94de:5c0e/1282c19:dd:d9:dd:c25:c25:94de:5c0e
162c19:dd:d9:dd:c25:c25:94de:5c0f/1282c19:dd:d9:dd:c25:c25:94de:5c0f
172c19:dd:d9:dd:c25:c25:94de:5c10/1282c19:dd:d9:dd:c25:c25:94de:5c10
182c19:dd:d9:dd:c25:c25:94de:5c11/1282c19:dd:d9:dd:c25:c25:94de:5c11
192c19:dd:d9:dd:c25:c25:94de:5c12/1282c19:dd:d9:dd:c25:c25:94de:5c12
202c19:dd:d9:dd:c25:c25:94de:5c13/1282c19:dd:d9:dd:c25:c25:94de:5c13
212c19:dd:d9:dd:c25:c25:94de:5c14/1282c19:dd:d9:dd:c25:c25:94de:5c14
222c19:dd:d9:dd:c25:c25:94de:5c15/1282c19:dd:d9:dd:c25:c25:94de:5c15
232c19:dd:d9:dd:c25:c25:94de:5c16/1282c19:dd:d9:dd:c25:c25:94de:5c16
242c19:dd:d9:dd:c25:c25:94de:5c17/1282c19:dd:d9:dd:c25:c25:94de:5c17
252c19:dd:d9:dd:c25:c25:94de:5c18/1282c19:dd:d9:dd:c25:c25:94de:5c18
262c19:dd:d9:dd:c25:c25:94de:5c19/1282c19:dd:d9:dd:c25:c25:94de:5c19
272c19:dd:d9:dd:c25:c25:94de:5c1a/1282c19:dd:d9:dd:c25:c25:94de:5c1a
282c19:dd:d9:dd:c25:c25:94de:5c1b/1282c19:dd:d9:dd:c25:c25:94de:5c1b
292c19:dd:d9:dd:c25:c25:94de:5c1c/1282c19:dd:d9:dd:c25:c25:94de:5c1c
302c19:dd:d9:dd:c25:c25:94de:5c1d/1282c19:dd:d9:dd:c25:c25:94de:5c1d
312c19:dd:d9:dd:c25:c25:94de:5c1e/1282c19:dd:d9:dd:c25:c25:94de:5c1e
322c19:dd:d9:dd:c25:c25:94de:5c1f/1282c19:dd:d9:dd:c25:c25:94de:5c1f
332c19:dd:d9:dd:c25:c25:94de:5c20/1282c19:dd:d9:dd:c25:c25:94de:5c20
342c19:dd:d9:dd:c25:c25:94de:5c21/1282c19:dd:d9:dd:c25:c25:94de:5c21
352c19:dd:d9:dd:c25:c25:94de:5c22/1282c19:dd:d9:dd:c25:c25:94de:5c22
362c19:dd:d9:dd:c25:c25:94de:5c23/1282c19:dd:d9:dd:c25:c25:94de:5c23
372c19:dd:d9:dd:c25:c25:94de:5c24/1282c19:dd:d9:dd:c25:c25:94de:5c24
382c19:dd:d9:dd:c25:c25:94de:5c25/1282c19:dd:d9:dd:c25:c25:94de:5c25
392c19:dd:d9:dd:c25:c25:94de:5c26/1282c19:dd:d9:dd:c25:c25:94de:5c26
402c19:dd:d9:dd:c25:c25:94de:5c27/1282c19:dd:d9:dd:c25:c25:94de:5c27
412c19:dd:d9:dd:c25:c25:94de:5c28/1282c19:dd:d9:dd:c25:c25:94de:5c28
422c19:dd:d9:dd:c25:c25:94de:5c29/1282c19:dd:d9:dd:c25:c25:94de:5c29
432c19:dd:d9:dd:c25:c25:94de:5c2a/1282c19:dd:d9:dd:c25:c25:94de:5c2a
442c19:dd:d9:dd:c25:c25:94de:5c2b/1282c19:dd:d9:dd:c25:c25:94de:5c2b
452c19:dd:d9:dd:c25:c25:94de:5c2c/1282c19:dd:d9:dd:c25:c25:94de:5c2c
462c19:dd:d9:dd:c25:c25:94de:5c2d/1282c19:dd:d9:dd:c25:c25:94de:5c2d
472c19:dd:d9:dd:c25:c25:94de:5c2e/1282c19:dd:d9:dd:c25:c25:94de:5c2e
482c19:dd:d9:dd:c25:c25:94de:5c2f/1282c19:dd:d9:dd:c25:c25:94de:5c2f
492c19:dd:d9:dd:c25:c25:94de:5c30/1282c19:dd:d9:dd:c25:c25:94de:5c30
502c19:dd:d9:dd:c25:c25:94de:5c31/1282c19:dd:d9:dd:c25:c25:94de:5c31
512c19:dd:d9:dd:c25:c25:94de:5c32/1282c19:dd:d9:dd:c25:c25:94de:5c32
522c19:dd:d9:dd:c25:c25:94de:5c33/1282c19:dd:d9:dd:c25:c25:94de:5c33
532c19:dd:d9:dd:c25:c25:94de:5c34/1282c19:dd:d9:dd:c25:c25:94de:5c34
542c19:dd:d9:dd:c25:c25:94de:5c35/1282c19:dd:d9:dd:c25:c25:94de:5c35
552c19:dd:d9:dd:c25:c25:94de:5c36/1282c19:dd:d9:dd:c25:c25:94de:5c36
562c19:dd:d9:dd:c25:c25:94de:5c37/1282c19:dd:d9:dd:c25:c25:94de:5c37
572c19:dd:d9:dd:c25:c25:94de:5c38/1282c19:dd:d9:dd:c25:c25:94de:5c38
582c19:dd:d9:dd:c25:c25:94de:5c39/1282c19:dd:d9:dd:c25:c25:94de:5c39
592c19:dd:d9:dd:c25:c25:94de:5c3a/1282c19:dd:d9:dd:c25:c25:94de:5c3a
602c19:dd:d9:dd:c25:c25:94de:5c3b/1282c19:dd:d9:dd:c25:c25:94de:5c3b
612c19:dd:d9:dd:c25:c25:94de:5c3c/1282c19:dd:d9:dd:c25:c25:94de:5c3c
622c19:dd:d9:dd:c25:c25:94de:5c3d/1282c19:dd:d9:dd:c25:c25:94de:5c3d
632c19:dd:d9:dd:c25:c25:94de:5c3e/1282c19:dd:d9:dd:c25:c25:94de:5c3e
642c19:dd:d9:dd:c25:c25:94de:5c3f/1282c19:dd:d9:dd:c25:c25:94de:5c3f
652c19:dd:d9:dd:c25:c25:94de:5c40/1282c19:dd:d9:dd:c25:c25:94de:5c40
662c19:dd:d9:dd:c25:c25:94de:5c41/1282c19:dd:d9:dd:c25:c25:94de:5c41
672c19:dd:d9:dd:c25:c25:94de:5c42/1282c19:dd:d9:dd:c25:c25:94de:5c42
682c19:dd:d9:dd:c25:c25:94de:5c43/1282c19:dd:d9:dd:c25:c25:94de:5c43
692c19:dd:d9:dd:c25:c25:94de:5c44/1282c19:dd:d9:dd:c25:c25:94de:5c44
702c19:dd:d9:dd:c25:c25:94de:5c45/1282c19:dd:d9:dd:c25:c25:94de:5c45
712c19:dd:d9:dd:c25:c25:94de:5c46/1282c19:dd:d9:dd:c25:c25:94de:5c46
722c19:dd:d9:dd:c25:c25:94de:5c47/1282c19:dd:d9:dd:c25:c25:94de:5c47
732c19:dd:d9:dd:c25:c25:94de:5c48/1282c19:dd:d9:dd:c25:c25:94de:5c48
742c19:dd:d9:dd:c25:c25:94de:5c49/1282c19:dd:d9:dd:c25:c25:94de:5c49
752c19:dd:d9:dd:c25:c25:94de:5c4a/1282c19:dd:d9:dd:c25:c25:94de:5c4a
762c19:dd:d9:dd:c25:c25:94de:5c4b/1282c19:dd:d9:dd:c25:c25:94de:5c4b
772c19:dd:d9:dd:c25:c25:94de:5c4c/1282c19:dd:d9:dd:c25:c25:94de:5c4c
782c19:dd:d9:dd:c25:c25:94de:5c4d/1282c19:dd:d9:dd:c25:c25:94de:5c4d
792c19:dd:d9:dd:c25:c25:94de:5c4e/1282c19:dd:d9:dd:c25:c25:94de:5c4e
802c19:dd:d9:dd:c25:c25:94de:5c4f/1282c19:dd:d9:dd:c25:c25:94de:5c4f
812c19:dd:d9:dd:c25:c25:94de:5c50/1282c19:dd:d9:dd:c25:c25:94de:5c50
822c19:dd:d9:dd:c25:c25:94de:5c51/1282c19:dd:d9:dd:c25:c25:94de:5c51
832c19:dd:d9:dd:c25:c25:94de:5c52/1282c19:dd:d9:dd:c25:c25:94de:5c52
842c19:dd:d9:dd:c25:c25:94de:5c53/1282c19:dd:d9:dd:c25:c25:94de:5c53
852c19:dd:d9:dd:c25:c25:94de:5c54/1282c19:dd:d9:dd:c25:c25:94de:5c54
862c19:dd:d9:dd:c25:c25:94de:5c55/1282c19:dd:d9:dd:c25:c25:94de:5c55
872c19:dd:d9:dd:c25:c25:94de:5c56/1282c19:dd:d9:dd:c25:c25:94de:5c56
882c19:dd:d9:dd:c25:c25:94de:5c57/1282c19:dd:d9:dd:c25:c25:94de:5c57
892c19:dd:d9:dd:c25:c25:94de:5c58/1282c19:dd:d9:dd:c25:c25:94de:5c58
902c19:dd:d9:dd:c25:c25:94de:5c59/1282c19:dd:d9:dd:c25:c25:94de:5c59
912c19:dd:d9:dd:c25:c25:94de:5c5a/1282c19:dd:d9:dd:c25:c25:94de:5c5a
922c19:dd:d9:dd:c25:c25:94de:5c5b/1282c19:dd:d9:dd:c25:c25:94de:5c5b
932c19:dd:d9:dd:c25:c25:94de:5c5c/1282c19:dd:d9:dd:c25:c25:94de:5c5c
942c19:dd:d9:dd:c25:c25:94de:5c5d/1282c19:dd:d9:dd:c25:c25:94de:5c5d
952c19:dd:d9:dd:c25:c25:94de:5c5e/1282c19:dd:d9:dd:c25:c25:94de:5c5e
962c19:dd:d9:dd:c25:c25:94de:5c5f/1282c19:dd:d9:dd:c25:c25:94de:5c5f
972c19:dd:d9:dd:c25:c25:94de:5c60/1282c19:dd:d9:dd:c25:c25:94de:5c60
982c19:dd:d9:dd:c25:c25:94de:5c61/1282c19:dd:d9:dd:c25:c25:94de:5c61
992c19:dd:d9:dd:c25:c25:94de:5c62/1282c19:dd:d9:dd:c25:c25:94de:5c62
1002c19:dd:d9:dd:c25:c25:94de:5c63/1282c19:dd:d9:dd:c25:c25:94de:5c63
1012c19:dd:d9:dd:c25:c25:94de:5c64/1282c19:dd:d9:dd:c25:c25:94de:5c64
1022c19:dd:d9:dd:c25:c25:94de:5c65/1282c19:dd:d9:dd:c25:c25:94de:5c65
1032c19:dd:d9:dd:c25:c25:94de:5c66/1282c19:dd:d9:dd:c25:c25:94de:5c66
1042c19:dd:d9:dd:c25:c25:94de:5c67/1282c19:dd:d9:dd:c25:c25:94de:5c67
1052c19:dd:d9:dd:c25:c25:94de:5c68/1282c19:dd:d9:dd:c25:c25:94de:5c68
1062c19:dd:d9:dd:c25:c25:94de:5c69/1282c19:dd:d9:dd:c25:c25:94de:5c69
1072c19:dd:d9:dd:c25:c25:94de:5c6a/1282c19:dd:d9:dd:c25:c25:94de:5c6a
1082c19:dd:d9:dd:c25:c25:94de:5c6b/1282c19:dd:d9:dd:c25:c25:94de:5c6b
1092c19:dd:d9:dd:c25:c25:94de:5c6c/1282c19:dd:d9:dd:c25:c25:94de:5c6c
1102c19:dd:d9:dd:c25:c25:94de:5c6d/1282c19:dd:d9:dd:c25:c25:94de:5c6d
1112c19:dd:d9:dd:c25:c25:94de:5c6e/1282c19:dd:d9:dd:c25:c25:94de:5c6e
1122c19:dd:d9:dd:c25:c25:94de:5c6f/1282c19:dd:d9:dd:c25:c25:94de:5c6f
1132c19:dd:d9:dd:c25:c25:94de:5c70/1282c19:dd:d9:dd:c25:c25:94de:5c70
1142c19:dd:d9:dd:c25:c25:94de:5c71/1282c19:dd:d9:dd:c25:c25:94de:5c71
1152c19:dd:d9:dd:c25:c25:94de:5c72/1282c19:dd:d9:dd:c25:c25:94de:5c72
1162c19:dd:d9:dd:c25:c25:94de:5c73/1282c19:dd:d9:dd:c25:c25:94de:5c73
1172c19:dd:d9:dd:c25:c25:94de:5c74/1282c19:dd:d9:dd:c25:c25:94de:5c74
1182c19:dd:d9:dd:c25:c25:94de:5c75/1282c19:dd:d9:dd:c25:c25:94de:5c75
1192c19:dd:d9:dd:c25:c25:94de:5c76/1282c19:dd:d9:dd:c25:c25:94de:5c76
1202c19:dd:d9:dd:c25:c25:94de:5c77/1282c19:dd:d9:dd:c25:c25:94de:5c77
1212c19:dd:d9:dd:c25:c25:94de:5c78/1282c19:dd:d9:dd:c25:c25:94de:5c78
1222c19:dd:d9:dd:c25:c25:94de:5c79/1282c19:dd:d9:dd:c25:c25:94de:5c79
1232c19:dd:d9:dd:c25:c25:94de:5c7a/1282c19:dd:d9:dd:c25:c25:94de:5c7a
1242c19:dd:d9:dd:c25:c25:94de:5c7b/1282c19:dd:d9:dd:c25:c25:94de:5c7b
1252c19:dd:d9:dd:c25:c25:94de:5c7c/1282c19:dd:d9:dd:c25:c25:94de:5c7c
1262c19:dd:d9:dd:c25:c25:94de:5c7d/1282c19:dd:d9:dd:c25:c25:94de:5c7d
1272c19:dd:d9:dd:c25:c25:94de:5c7e/1282c19:dd:d9:dd:c25:c25:94de:5c7e
1282c19:dd:d9:dd:c25:c25:94de:5c7f/1282c19:dd:d9:dd:c25:c25:94de:5c7f
1292c19:dd:d9:dd:c25:c25:94de:5c80/1282c19:dd:d9:dd:c25:c25:94de:5c80
1302c19:dd:d9:dd:c25:c25:94de:5c81/1282c19:dd:d9:dd:c25:c25:94de:5c81
1312c19:dd:d9:dd:c25:c25:94de:5c82/1282c19:dd:d9:dd:c25:c25:94de:5c82
1322c19:dd:d9:dd:c25:c25:94de:5c83/1282c19:dd:d9:dd:c25:c25:94de:5c83
1332c19:dd:d9:dd:c25:c25:94de:5c84/1282c19:dd:d9:dd:c25:c25:94de:5c84
1342c19:dd:d9:dd:c25:c25:94de:5c85/1282c19:dd:d9:dd:c25:c25:94de:5c85
1352c19:dd:d9:dd:c25:c25:94de:5c86/1282c19:dd:d9:dd:c25:c25:94de:5c86
1362c19:dd:d9:dd:c25:c25:94de:5c87/1282c19:dd:d9:dd:c25:c25:94de:5c87
1372c19:dd:d9:dd:c25:c25:94de:5c88/1282c19:dd:d9:dd:c25:c25:94de:5c88
1382c19:dd:d9:dd:c25:c25:94de:5c89/1282c19:dd:d9:dd:c25:c25:94de:5c89
1392c19:dd:d9:dd:c25:c25:94de:5c8a/1282c19:dd:d9:dd:c25:c25:94de:5c8a
1402c19:dd:d9:dd:c25:c25:94de:5c8b/1282c19:dd:d9:dd:c25:c25:94de:5c8b
1412c19:dd:d9:dd:c25:c25:94de:5c8c/1282c19:dd:d9:dd:c25:c25:94de:5c8c
1422c19:dd:d9:dd:c25:c25:94de:5c8d/1282c19:dd:d9:dd:c25:c25:94de:5c8d
1432c19:dd:d9:dd:c25:c25:94de:5c8e/1282c19:dd:d9:dd:c25:c25:94de:5c8e
1442c19:dd:d9:dd:c25:c25:94de:5c8f/1282c19:dd:d9:dd:c25:c25:94de:5c8f
1452c19:dd:d9:dd:c25:c25:94de:5c90/1282c19:dd:d9:dd:c25:c25:94de:5c90
1462c19:dd:d9:dd:c25:c25:94de:5c91/1282c19:dd:d9:dd:c25:c25:94de:5c91
1472c19:dd:d9:dd:c25:c25:94de:5c92/1282c19:dd:d9:dd:c25:c25:94de:5c92
1482c19:dd:d9:dd:c25:c25:94de:5c93/1282c19:dd:d9:dd:c25:c25:94de:5c93
1492c19:dd:d9:dd:c25:c25:94de:5c94/1282c19:dd:d9:dd:c25:c25:94de:5c94
1502c19:dd:d9:dd:c25:c25:94de:5c95/1282c19:dd:d9:dd:c25:c25:94de:5c95
1512c19:dd:d9:dd:c25:c25:94de:5c96/1282c19:dd:d9:dd:c25:c25:94de:5c96
1522c19:dd:d9:dd:c25:c25:94de:5c97/1282c19:dd:d9:dd:c25:c25:94de:5c97
1532c19:dd:d9:dd:c25:c25:94de:5c98/1282c19:dd:d9:dd:c25:c25:94de:5c98
1542c19:dd:d9:dd:c25:c25:94de:5c99/1282c19:dd:d9:dd:c25:c25:94de:5c99
1552c19:dd:d9:dd:c25:c25:94de:5c9a/1282c19:dd:d9:dd:c25:c25:94de:5c9a
1562c19:dd:d9:dd:c25:c25:94de:5c9b/1282c19:dd:d9:dd:c25:c25:94de:5c9b
1572c19:dd:d9:dd:c25:c25:94de:5c9c/1282c19:dd:d9:dd:c25:c25:94de:5c9c
1582c19:dd:d9:dd:c25:c25:94de:5c9d/1282c19:dd:d9:dd:c25:c25:94de:5c9d
1592c19:dd:d9:dd:c25:c25:94de:5c9e/1282c19:dd:d9:dd:c25:c25:94de:5c9e
1602c19:dd:d9:dd:c25:c25:94de:5c9f/1282c19:dd:d9:dd:c25:c25:94de:5c9f
1612c19:dd:d9:dd:c25:c25:94de:5ca0/1282c19:dd:d9:dd:c25:c25:94de:5ca0
1622c19:dd:d9:dd:c25:c25:94de:5ca1/1282c19:dd:d9:dd:c25:c25:94de:5ca1
1632c19:dd:d9:dd:c25:c25:94de:5ca2/1282c19:dd:d9:dd:c25:c25:94de:5ca2
1642c19:dd:d9:dd:c25:c25:94de:5ca3/1282c19:dd:d9:dd:c25:c25:94de:5ca3
1652c19:dd:d9:dd:c25:c25:94de:5ca4/1282c19:dd:d9:dd:c25:c25:94de:5ca4
1662c19:dd:d9:dd:c25:c25:94de:5ca5/1282c19:dd:d9:dd:c25:c25:94de:5ca5
1672c19:dd:d9:dd:c25:c25:94de:5ca6/1282c19:dd:d9:dd:c25:c25:94de:5ca6
1682c19:dd:d9:dd:c25:c25:94de:5ca7/1282c19:dd:d9:dd:c25:c25:94de:5ca7
1692c19:dd:d9:dd:c25:c25:94de:5ca8/1282c19:dd:d9:dd:c25:c25:94de:5ca8
1702c19:dd:d9:dd:c25:c25:94de:5ca9/1282c19:dd:d9:dd:c25:c25:94de:5ca9
1712c19:dd:d9:dd:c25:c25:94de:5caa/1282c19:dd:d9:dd:c25:c25:94de:5caa
1722c19:dd:d9:dd:c25:c25:94de:5cab/1282c19:dd:d9:dd:c25:c25:94de:5cab
1732c19:dd:d9:dd:c25:c25:94de:5cac/1282c19:dd:d9:dd:c25:c25:94de:5cac
1742c19:dd:d9:dd:c25:c25:94de:5cad/1282c19:dd:d9:dd:c25:c25:94de:5cad
1752c19:dd:d9:dd:c25:c25:94de:5cae/1282c19:dd:d9:dd:c25:c25:94de:5cae
1762c19:dd:d9:dd:c25:c25:94de:5caf/1282c19:dd:d9:dd:c25:c25:94de:5caf
1772c19:dd:d9:dd:c25:c25:94de:5cb0/1282c19:dd:d9:dd:c25:c25:94de:5cb0
1782c19:dd:d9:dd:c25:c25:94de:5cb1/1282c19:dd:d9:dd:c25:c25:94de:5cb1
1792c19:dd:d9:dd:c25:c25:94de:5cb2/1282c19:dd:d9:dd:c25:c25:94de:5cb2
1802c19:dd:d9:dd:c25:c25:94de:5cb3/1282c19:dd:d9:dd:c25:c25:94de:5cb3
1812c19:dd:d9:dd:c25:c25:94de:5cb4/1282c19:dd:d9:dd:c25:c25:94de:5cb4
1822c19:dd:d9:dd:c25:c25:94de:5cb5/1282c19:dd:d9:dd:c25:c25:94de:5cb5
1832c19:dd:d9:dd:c25:c25:94de:5cb6/1282c19:dd:d9:dd:c25:c25:94de:5cb6
1842c19:dd:d9:dd:c25:c25:94de:5cb7/1282c19:dd:d9:dd:c25:c25:94de:5cb7
1852c19:dd:d9:dd:c25:c25:94de:5cb8/1282c19:dd:d9:dd:c25:c25:94de:5cb8
1862c19:dd:d9:dd:c25:c25:94de:5cb9/1282c19:dd:d9:dd:c25:c25:94de:5cb9
1872c19:dd:d9:dd:c25:c25:94de:5cba/1282c19:dd:d9:dd:c25:c25:94de:5cba
1882c19:dd:d9:dd:c25:c25:94de:5cbb/1282c19:dd:d9:dd:c25:c25:94de:5cbb
1892c19:dd:d9:dd:c25:c25:94de:5cbc/1282c19:dd:d9:dd:c25:c25:94de:5cbc
1902c19:dd:d9:dd:c25:c25:94de:5cbd/1282c19:dd:d9:dd:c25:c25:94de:5cbd
1912c19:dd:d9:dd:c25:c25:94de:5cbe/1282c19:dd:d9:dd:c25:c25:94de:5cbe
1922c19:dd:d9:dd:c25:c25:94de:5cbf/1282c19:dd:d9:dd:c25:c25:94de:5cbf
1932c19:dd:d9:dd:c25:c25:94de:5cc0/1282c19:dd:d9:dd:c25:c25:94de:5cc0
1942c19:dd:d9:dd:c25:c25:94de:5cc1/1282c19:dd:d9:dd:c25:c25:94de:5cc1
1952c19:dd:d9:dd:c25:c25:94de:5cc2/1282c19:dd:d9:dd:c25:c25:94de:5cc2
1962c19:dd:d9:dd:c25:c25:94de:5cc3/1282c19:dd:d9:dd:c25:c25:94de:5cc3
1972c19:dd:d9:dd:c25:c25:94de:5cc4/1282c19:dd:d9:dd:c25:c25:94de:5cc4
1982c19:dd:d9:dd:c25:c25:94de:5cc5/1282c19:dd:d9:dd:c25:c25:94de:5cc5
1992c19:dd:d9:dd:c25:c25:94de:5cc6/1282c19:dd:d9:dd:c25:c25:94de:5cc6
2002c19:dd:d9:dd:c25:c25:94de:5cc7/1282c19:dd:d9:dd:c25:c25:94de:5cc7
2012c19:dd:d9:dd:c25:c25:94de:5cc8/1282c19:dd:d9:dd:c25:c25:94de:5cc8
2022c19:dd:d9:dd:c25:c25:94de:5cc9/1282c19:dd:d9:dd:c25:c25:94de:5cc9
2032c19:dd:d9:dd:c25:c25:94de:5cca/1282c19:dd:d9:dd:c25:c25:94de:5cca
2042c19:dd:d9:dd:c25:c25:94de:5ccb/1282c19:dd:d9:dd:c25:c25:94de:5ccb
2052c19:dd:d9:dd:c25:c25:94de:5ccc/1282c19:dd:d9:dd:c25:c25:94de:5ccc
2062c19:dd:d9:dd:c25:c25:94de:5ccd/1282c19:dd:d9:dd:c25:c25:94de:5ccd
2072c19:dd:d9:dd:c25:c25:94de:5cce/1282c19:dd:d9:dd:c25:c25:94de:5cce
2082c19:dd:d9:dd:c25:c25:94de:5ccf/1282c19:dd:d9:dd:c25:c25:94de:5ccf
2092c19:dd:d9:dd:c25:c25:94de:5cd0/1282c19:dd:d9:dd:c25:c25:94de:5cd0
2102c19:dd:d9:dd:c25:c25:94de:5cd1/1282c19:dd:d9:dd:c25:c25:94de:5cd1
2112c19:dd:d9:dd:c25:c25:94de:5cd2/1282c19:dd:d9:dd:c25:c25:94de:5cd2
2122c19:dd:d9:dd:c25:c25:94de:5cd3/1282c19:dd:d9:dd:c25:c25:94de:5cd3
2132c19:dd:d9:dd:c25:c25:94de:5cd4/1282c19:dd:d9:dd:c25:c25:94de:5cd4
2142c19:dd:d9:dd:c25:c25:94de:5cd5/1282c19:dd:d9:dd:c25:c25:94de:5cd5
2152c19:dd:d9:dd:c25:c25:94de:5cd6/1282c19:dd:d9:dd:c25:c25:94de:5cd6
2162c19:dd:d9:dd:c25:c25:94de:5cd7/1282c19:dd:d9:dd:c25:c25:94de:5cd7
2172c19:dd:d9:dd:c25:c25:94de:5cd8/1282c19:dd:d9:dd:c25:c25:94de:5cd8
2182c19:dd:d9:dd:c25:c25:94de:5cd9/1282c19:dd:d9:dd:c25:c25:94de:5cd9
2192c19:dd:d9:dd:c25:c25:94de:5cda/1282c19:dd:d9:dd:c25:c25:94de:5cda
2202c19:dd:d9:dd:c25:c25:94de:5cdb/1282c19:dd:d9:dd:c25:c25:94de:5cdb
2212c19:dd:d9:dd:c25:c25:94de:5cdc/1282c19:dd:d9:dd:c25:c25:94de:5cdc
2222c19:dd:d9:dd:c25:c25:94de:5cdd/1282c19:dd:d9:dd:c25:c25:94de:5cdd
2232c19:dd:d9:dd:c25:c25:94de:5cde/1282c19:dd:d9:dd:c25:c25:94de:5cde
2242c19:dd:d9:dd:c25:c25:94de:5cdf/1282c19:dd:d9:dd:c25:c25:94de:5cdf
2252c19:dd:d9:dd:c25:c25:94de:5ce0/1282c19:dd:d9:dd:c25:c25:94de:5ce0
2262c19:dd:d9:dd:c25:c25:94de:5ce1/1282c19:dd:d9:dd:c25:c25:94de:5ce1
2272c19:dd:d9:dd:c25:c25:94de:5ce2/1282c19:dd:d9:dd:c25:c25:94de:5ce2
2282c19:dd:d9:dd:c25:c25:94de:5ce3/1282c19:dd:d9:dd:c25:c25:94de:5ce3
2292c19:dd:d9:dd:c25:c25:94de:5ce4/1282c19:dd:d9:dd:c25:c25:94de:5ce4
2302c19:dd:d9:dd:c25:c25:94de:5ce5/1282c19:dd:d9:dd:c25:c25:94de:5ce5
2312c19:dd:d9:dd:c25:c25:94de:5ce6/1282c19:dd:d9:dd:c25:c25:94de:5ce6
2322c19:dd:d9:dd:c25:c25:94de:5ce7/1282c19:dd:d9:dd:c25:c25:94de:5ce7
2332c19:dd:d9:dd:c25:c25:94de:5ce8/1282c19:dd:d9:dd:c25:c25:94de:5ce8
2342c19:dd:d9:dd:c25:c25:94de:5ce9/1282c19:dd:d9:dd:c25:c25:94de:5ce9
2352c19:dd:d9:dd:c25:c25:94de:5cea/1282c19:dd:d9:dd:c25:c25:94de:5cea
2362c19:dd:d9:dd:c25:c25:94de:5ceb/1282c19:dd:d9:dd:c25:c25:94de:5ceb
2372c19:dd:d9:dd:c25:c25:94de:5cec/1282c19:dd:d9:dd:c25:c25:94de:5cec
2382c19:dd:d9:dd:c25:c25:94de:5ced/1282c19:dd:d9:dd:c25:c25:94de:5ced
2392c19:dd:d9:dd:c25:c25:94de:5cee/1282c19:dd:d9:dd:c25:c25:94de:5cee
2402c19:dd:d9:dd:c25:c25:94de:5cef/1282c19:dd:d9:dd:c25:c25:94de:5cef
2412c19:dd:d9:dd:c25:c25:94de:5cf0/1282c19:dd:d9:dd:c25:c25:94de:5cf0
2422c19:dd:d9:dd:c25:c25:94de:5cf1/1282c19:dd:d9:dd:c25:c25:94de:5cf1
2432c19:dd:d9:dd:c25:c25:94de:5cf2/1282c19:dd:d9:dd:c25:c25:94de:5cf2
2442c19:dd:d9:dd:c25:c25:94de:5cf3/1282c19:dd:d9:dd:c25:c25:94de:5cf3
2452c19:dd:d9:dd:c25:c25:94de:5cf4/1282c19:dd:d9:dd:c25:c25:94de:5cf4
2462c19:dd:d9:dd:c25:c25:94de:5cf5/1282c19:dd:d9:dd:c25:c25:94de:5cf5
2472c19:dd:d9:dd:c25:c25:94de:5cf6/1282c19:dd:d9:dd:c25:c25:94de:5cf6
2482c19:dd:d9:dd:c25:c25:94de:5cf7/1282c19:dd:d9:dd:c25:c25:94de:5cf7
2492c19:dd:d9:dd:c25:c25:94de:5cf8/1282c19:dd:d9:dd:c25:c25:94de:5cf8
2502c19:dd:d9:dd:c25:c25:94de:5cf9/1282c19:dd:d9:dd:c25:c25:94de:5cf9
2512c19:dd:d9:dd:c25:c25:94de:5cfa/1282c19:dd:d9:dd:c25:c25:94de:5cfa
2522c19:dd:d9:dd:c25:c25:94de:5cfb/1282c19:dd:d9:dd:c25:c25:94de:5cfb
2532c19:dd:d9:dd:c25:c25:94de:5cfc/1282c19:dd:d9:dd:c25:c25:94de:5cfc
2542c19:dd:d9:dd:c25:c25:94de:5cfd/1282c19:dd:d9:dd:c25:c25:94de:5cfd
2552c19:dd:d9:dd:c25:c25:94de:5cfe/1282c19:dd:d9:dd:c25:c25:94de:5cfe
2562c19:dd:d9:dd:c25:c25:94de:5cff/1282c19:dd:d9:dd:c25:c25:94de:5cff

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.