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:c25a:d00a:bd00/120
First address
2c19:dd:d9:dd:c25:c25a:d00a:bd00
Last address
2c19:dd:d9:dd:c25:c25a:d00a:bdff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:c25a:d00a:bd00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
d.b.a.0.0.d.a.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:c25a:d00a:bd00/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25a:d00a:bd00/1282c19:dd:d9:dd:c25:c25a:d00a:bd00
22c19:dd:d9:dd:c25:c25a:d00a:bd01/1282c19:dd:d9:dd:c25:c25a:d00a:bd01
32c19:dd:d9:dd:c25:c25a:d00a:bd02/1282c19:dd:d9:dd:c25:c25a:d00a:bd02
42c19:dd:d9:dd:c25:c25a:d00a:bd03/1282c19:dd:d9:dd:c25:c25a:d00a:bd03
52c19:dd:d9:dd:c25:c25a:d00a:bd04/1282c19:dd:d9:dd:c25:c25a:d00a:bd04
62c19:dd:d9:dd:c25:c25a:d00a:bd05/1282c19:dd:d9:dd:c25:c25a:d00a:bd05
72c19:dd:d9:dd:c25:c25a:d00a:bd06/1282c19:dd:d9:dd:c25:c25a:d00a:bd06
82c19:dd:d9:dd:c25:c25a:d00a:bd07/1282c19:dd:d9:dd:c25:c25a:d00a:bd07
92c19:dd:d9:dd:c25:c25a:d00a:bd08/1282c19:dd:d9:dd:c25:c25a:d00a:bd08
102c19:dd:d9:dd:c25:c25a:d00a:bd09/1282c19:dd:d9:dd:c25:c25a:d00a:bd09
112c19:dd:d9:dd:c25:c25a:d00a:bd0a/1282c19:dd:d9:dd:c25:c25a:d00a:bd0a
122c19:dd:d9:dd:c25:c25a:d00a:bd0b/1282c19:dd:d9:dd:c25:c25a:d00a:bd0b
132c19:dd:d9:dd:c25:c25a:d00a:bd0c/1282c19:dd:d9:dd:c25:c25a:d00a:bd0c
142c19:dd:d9:dd:c25:c25a:d00a:bd0d/1282c19:dd:d9:dd:c25:c25a:d00a:bd0d
152c19:dd:d9:dd:c25:c25a:d00a:bd0e/1282c19:dd:d9:dd:c25:c25a:d00a:bd0e
162c19:dd:d9:dd:c25:c25a:d00a:bd0f/1282c19:dd:d9:dd:c25:c25a:d00a:bd0f
172c19:dd:d9:dd:c25:c25a:d00a:bd10/1282c19:dd:d9:dd:c25:c25a:d00a:bd10
182c19:dd:d9:dd:c25:c25a:d00a:bd11/1282c19:dd:d9:dd:c25:c25a:d00a:bd11
192c19:dd:d9:dd:c25:c25a:d00a:bd12/1282c19:dd:d9:dd:c25:c25a:d00a:bd12
202c19:dd:d9:dd:c25:c25a:d00a:bd13/1282c19:dd:d9:dd:c25:c25a:d00a:bd13
212c19:dd:d9:dd:c25:c25a:d00a:bd14/1282c19:dd:d9:dd:c25:c25a:d00a:bd14
222c19:dd:d9:dd:c25:c25a:d00a:bd15/1282c19:dd:d9:dd:c25:c25a:d00a:bd15
232c19:dd:d9:dd:c25:c25a:d00a:bd16/1282c19:dd:d9:dd:c25:c25a:d00a:bd16
242c19:dd:d9:dd:c25:c25a:d00a:bd17/1282c19:dd:d9:dd:c25:c25a:d00a:bd17
252c19:dd:d9:dd:c25:c25a:d00a:bd18/1282c19:dd:d9:dd:c25:c25a:d00a:bd18
262c19:dd:d9:dd:c25:c25a:d00a:bd19/1282c19:dd:d9:dd:c25:c25a:d00a:bd19
272c19:dd:d9:dd:c25:c25a:d00a:bd1a/1282c19:dd:d9:dd:c25:c25a:d00a:bd1a
282c19:dd:d9:dd:c25:c25a:d00a:bd1b/1282c19:dd:d9:dd:c25:c25a:d00a:bd1b
292c19:dd:d9:dd:c25:c25a:d00a:bd1c/1282c19:dd:d9:dd:c25:c25a:d00a:bd1c
302c19:dd:d9:dd:c25:c25a:d00a:bd1d/1282c19:dd:d9:dd:c25:c25a:d00a:bd1d
312c19:dd:d9:dd:c25:c25a:d00a:bd1e/1282c19:dd:d9:dd:c25:c25a:d00a:bd1e
322c19:dd:d9:dd:c25:c25a:d00a:bd1f/1282c19:dd:d9:dd:c25:c25a:d00a:bd1f
332c19:dd:d9:dd:c25:c25a:d00a:bd20/1282c19:dd:d9:dd:c25:c25a:d00a:bd20
342c19:dd:d9:dd:c25:c25a:d00a:bd21/1282c19:dd:d9:dd:c25:c25a:d00a:bd21
352c19:dd:d9:dd:c25:c25a:d00a:bd22/1282c19:dd:d9:dd:c25:c25a:d00a:bd22
362c19:dd:d9:dd:c25:c25a:d00a:bd23/1282c19:dd:d9:dd:c25:c25a:d00a:bd23
372c19:dd:d9:dd:c25:c25a:d00a:bd24/1282c19:dd:d9:dd:c25:c25a:d00a:bd24
382c19:dd:d9:dd:c25:c25a:d00a:bd25/1282c19:dd:d9:dd:c25:c25a:d00a:bd25
392c19:dd:d9:dd:c25:c25a:d00a:bd26/1282c19:dd:d9:dd:c25:c25a:d00a:bd26
402c19:dd:d9:dd:c25:c25a:d00a:bd27/1282c19:dd:d9:dd:c25:c25a:d00a:bd27
412c19:dd:d9:dd:c25:c25a:d00a:bd28/1282c19:dd:d9:dd:c25:c25a:d00a:bd28
422c19:dd:d9:dd:c25:c25a:d00a:bd29/1282c19:dd:d9:dd:c25:c25a:d00a:bd29
432c19:dd:d9:dd:c25:c25a:d00a:bd2a/1282c19:dd:d9:dd:c25:c25a:d00a:bd2a
442c19:dd:d9:dd:c25:c25a:d00a:bd2b/1282c19:dd:d9:dd:c25:c25a:d00a:bd2b
452c19:dd:d9:dd:c25:c25a:d00a:bd2c/1282c19:dd:d9:dd:c25:c25a:d00a:bd2c
462c19:dd:d9:dd:c25:c25a:d00a:bd2d/1282c19:dd:d9:dd:c25:c25a:d00a:bd2d
472c19:dd:d9:dd:c25:c25a:d00a:bd2e/1282c19:dd:d9:dd:c25:c25a:d00a:bd2e
482c19:dd:d9:dd:c25:c25a:d00a:bd2f/1282c19:dd:d9:dd:c25:c25a:d00a:bd2f
492c19:dd:d9:dd:c25:c25a:d00a:bd30/1282c19:dd:d9:dd:c25:c25a:d00a:bd30
502c19:dd:d9:dd:c25:c25a:d00a:bd31/1282c19:dd:d9:dd:c25:c25a:d00a:bd31
512c19:dd:d9:dd:c25:c25a:d00a:bd32/1282c19:dd:d9:dd:c25:c25a:d00a:bd32
522c19:dd:d9:dd:c25:c25a:d00a:bd33/1282c19:dd:d9:dd:c25:c25a:d00a:bd33
532c19:dd:d9:dd:c25:c25a:d00a:bd34/1282c19:dd:d9:dd:c25:c25a:d00a:bd34
542c19:dd:d9:dd:c25:c25a:d00a:bd35/1282c19:dd:d9:dd:c25:c25a:d00a:bd35
552c19:dd:d9:dd:c25:c25a:d00a:bd36/1282c19:dd:d9:dd:c25:c25a:d00a:bd36
562c19:dd:d9:dd:c25:c25a:d00a:bd37/1282c19:dd:d9:dd:c25:c25a:d00a:bd37
572c19:dd:d9:dd:c25:c25a:d00a:bd38/1282c19:dd:d9:dd:c25:c25a:d00a:bd38
582c19:dd:d9:dd:c25:c25a:d00a:bd39/1282c19:dd:d9:dd:c25:c25a:d00a:bd39
592c19:dd:d9:dd:c25:c25a:d00a:bd3a/1282c19:dd:d9:dd:c25:c25a:d00a:bd3a
602c19:dd:d9:dd:c25:c25a:d00a:bd3b/1282c19:dd:d9:dd:c25:c25a:d00a:bd3b
612c19:dd:d9:dd:c25:c25a:d00a:bd3c/1282c19:dd:d9:dd:c25:c25a:d00a:bd3c
622c19:dd:d9:dd:c25:c25a:d00a:bd3d/1282c19:dd:d9:dd:c25:c25a:d00a:bd3d
632c19:dd:d9:dd:c25:c25a:d00a:bd3e/1282c19:dd:d9:dd:c25:c25a:d00a:bd3e
642c19:dd:d9:dd:c25:c25a:d00a:bd3f/1282c19:dd:d9:dd:c25:c25a:d00a:bd3f
652c19:dd:d9:dd:c25:c25a:d00a:bd40/1282c19:dd:d9:dd:c25:c25a:d00a:bd40
662c19:dd:d9:dd:c25:c25a:d00a:bd41/1282c19:dd:d9:dd:c25:c25a:d00a:bd41
672c19:dd:d9:dd:c25:c25a:d00a:bd42/1282c19:dd:d9:dd:c25:c25a:d00a:bd42
682c19:dd:d9:dd:c25:c25a:d00a:bd43/1282c19:dd:d9:dd:c25:c25a:d00a:bd43
692c19:dd:d9:dd:c25:c25a:d00a:bd44/1282c19:dd:d9:dd:c25:c25a:d00a:bd44
702c19:dd:d9:dd:c25:c25a:d00a:bd45/1282c19:dd:d9:dd:c25:c25a:d00a:bd45
712c19:dd:d9:dd:c25:c25a:d00a:bd46/1282c19:dd:d9:dd:c25:c25a:d00a:bd46
722c19:dd:d9:dd:c25:c25a:d00a:bd47/1282c19:dd:d9:dd:c25:c25a:d00a:bd47
732c19:dd:d9:dd:c25:c25a:d00a:bd48/1282c19:dd:d9:dd:c25:c25a:d00a:bd48
742c19:dd:d9:dd:c25:c25a:d00a:bd49/1282c19:dd:d9:dd:c25:c25a:d00a:bd49
752c19:dd:d9:dd:c25:c25a:d00a:bd4a/1282c19:dd:d9:dd:c25:c25a:d00a:bd4a
762c19:dd:d9:dd:c25:c25a:d00a:bd4b/1282c19:dd:d9:dd:c25:c25a:d00a:bd4b
772c19:dd:d9:dd:c25:c25a:d00a:bd4c/1282c19:dd:d9:dd:c25:c25a:d00a:bd4c
782c19:dd:d9:dd:c25:c25a:d00a:bd4d/1282c19:dd:d9:dd:c25:c25a:d00a:bd4d
792c19:dd:d9:dd:c25:c25a:d00a:bd4e/1282c19:dd:d9:dd:c25:c25a:d00a:bd4e
802c19:dd:d9:dd:c25:c25a:d00a:bd4f/1282c19:dd:d9:dd:c25:c25a:d00a:bd4f
812c19:dd:d9:dd:c25:c25a:d00a:bd50/1282c19:dd:d9:dd:c25:c25a:d00a:bd50
822c19:dd:d9:dd:c25:c25a:d00a:bd51/1282c19:dd:d9:dd:c25:c25a:d00a:bd51
832c19:dd:d9:dd:c25:c25a:d00a:bd52/1282c19:dd:d9:dd:c25:c25a:d00a:bd52
842c19:dd:d9:dd:c25:c25a:d00a:bd53/1282c19:dd:d9:dd:c25:c25a:d00a:bd53
852c19:dd:d9:dd:c25:c25a:d00a:bd54/1282c19:dd:d9:dd:c25:c25a:d00a:bd54
862c19:dd:d9:dd:c25:c25a:d00a:bd55/1282c19:dd:d9:dd:c25:c25a:d00a:bd55
872c19:dd:d9:dd:c25:c25a:d00a:bd56/1282c19:dd:d9:dd:c25:c25a:d00a:bd56
882c19:dd:d9:dd:c25:c25a:d00a:bd57/1282c19:dd:d9:dd:c25:c25a:d00a:bd57
892c19:dd:d9:dd:c25:c25a:d00a:bd58/1282c19:dd:d9:dd:c25:c25a:d00a:bd58
902c19:dd:d9:dd:c25:c25a:d00a:bd59/1282c19:dd:d9:dd:c25:c25a:d00a:bd59
912c19:dd:d9:dd:c25:c25a:d00a:bd5a/1282c19:dd:d9:dd:c25:c25a:d00a:bd5a
922c19:dd:d9:dd:c25:c25a:d00a:bd5b/1282c19:dd:d9:dd:c25:c25a:d00a:bd5b
932c19:dd:d9:dd:c25:c25a:d00a:bd5c/1282c19:dd:d9:dd:c25:c25a:d00a:bd5c
942c19:dd:d9:dd:c25:c25a:d00a:bd5d/1282c19:dd:d9:dd:c25:c25a:d00a:bd5d
952c19:dd:d9:dd:c25:c25a:d00a:bd5e/1282c19:dd:d9:dd:c25:c25a:d00a:bd5e
962c19:dd:d9:dd:c25:c25a:d00a:bd5f/1282c19:dd:d9:dd:c25:c25a:d00a:bd5f
972c19:dd:d9:dd:c25:c25a:d00a:bd60/1282c19:dd:d9:dd:c25:c25a:d00a:bd60
982c19:dd:d9:dd:c25:c25a:d00a:bd61/1282c19:dd:d9:dd:c25:c25a:d00a:bd61
992c19:dd:d9:dd:c25:c25a:d00a:bd62/1282c19:dd:d9:dd:c25:c25a:d00a:bd62
1002c19:dd:d9:dd:c25:c25a:d00a:bd63/1282c19:dd:d9:dd:c25:c25a:d00a:bd63
1012c19:dd:d9:dd:c25:c25a:d00a:bd64/1282c19:dd:d9:dd:c25:c25a:d00a:bd64
1022c19:dd:d9:dd:c25:c25a:d00a:bd65/1282c19:dd:d9:dd:c25:c25a:d00a:bd65
1032c19:dd:d9:dd:c25:c25a:d00a:bd66/1282c19:dd:d9:dd:c25:c25a:d00a:bd66
1042c19:dd:d9:dd:c25:c25a:d00a:bd67/1282c19:dd:d9:dd:c25:c25a:d00a:bd67
1052c19:dd:d9:dd:c25:c25a:d00a:bd68/1282c19:dd:d9:dd:c25:c25a:d00a:bd68
1062c19:dd:d9:dd:c25:c25a:d00a:bd69/1282c19:dd:d9:dd:c25:c25a:d00a:bd69
1072c19:dd:d9:dd:c25:c25a:d00a:bd6a/1282c19:dd:d9:dd:c25:c25a:d00a:bd6a
1082c19:dd:d9:dd:c25:c25a:d00a:bd6b/1282c19:dd:d9:dd:c25:c25a:d00a:bd6b
1092c19:dd:d9:dd:c25:c25a:d00a:bd6c/1282c19:dd:d9:dd:c25:c25a:d00a:bd6c
1102c19:dd:d9:dd:c25:c25a:d00a:bd6d/1282c19:dd:d9:dd:c25:c25a:d00a:bd6d
1112c19:dd:d9:dd:c25:c25a:d00a:bd6e/1282c19:dd:d9:dd:c25:c25a:d00a:bd6e
1122c19:dd:d9:dd:c25:c25a:d00a:bd6f/1282c19:dd:d9:dd:c25:c25a:d00a:bd6f
1132c19:dd:d9:dd:c25:c25a:d00a:bd70/1282c19:dd:d9:dd:c25:c25a:d00a:bd70
1142c19:dd:d9:dd:c25:c25a:d00a:bd71/1282c19:dd:d9:dd:c25:c25a:d00a:bd71
1152c19:dd:d9:dd:c25:c25a:d00a:bd72/1282c19:dd:d9:dd:c25:c25a:d00a:bd72
1162c19:dd:d9:dd:c25:c25a:d00a:bd73/1282c19:dd:d9:dd:c25:c25a:d00a:bd73
1172c19:dd:d9:dd:c25:c25a:d00a:bd74/1282c19:dd:d9:dd:c25:c25a:d00a:bd74
1182c19:dd:d9:dd:c25:c25a:d00a:bd75/1282c19:dd:d9:dd:c25:c25a:d00a:bd75
1192c19:dd:d9:dd:c25:c25a:d00a:bd76/1282c19:dd:d9:dd:c25:c25a:d00a:bd76
1202c19:dd:d9:dd:c25:c25a:d00a:bd77/1282c19:dd:d9:dd:c25:c25a:d00a:bd77
1212c19:dd:d9:dd:c25:c25a:d00a:bd78/1282c19:dd:d9:dd:c25:c25a:d00a:bd78
1222c19:dd:d9:dd:c25:c25a:d00a:bd79/1282c19:dd:d9:dd:c25:c25a:d00a:bd79
1232c19:dd:d9:dd:c25:c25a:d00a:bd7a/1282c19:dd:d9:dd:c25:c25a:d00a:bd7a
1242c19:dd:d9:dd:c25:c25a:d00a:bd7b/1282c19:dd:d9:dd:c25:c25a:d00a:bd7b
1252c19:dd:d9:dd:c25:c25a:d00a:bd7c/1282c19:dd:d9:dd:c25:c25a:d00a:bd7c
1262c19:dd:d9:dd:c25:c25a:d00a:bd7d/1282c19:dd:d9:dd:c25:c25a:d00a:bd7d
1272c19:dd:d9:dd:c25:c25a:d00a:bd7e/1282c19:dd:d9:dd:c25:c25a:d00a:bd7e
1282c19:dd:d9:dd:c25:c25a:d00a:bd7f/1282c19:dd:d9:dd:c25:c25a:d00a:bd7f
1292c19:dd:d9:dd:c25:c25a:d00a:bd80/1282c19:dd:d9:dd:c25:c25a:d00a:bd80
1302c19:dd:d9:dd:c25:c25a:d00a:bd81/1282c19:dd:d9:dd:c25:c25a:d00a:bd81
1312c19:dd:d9:dd:c25:c25a:d00a:bd82/1282c19:dd:d9:dd:c25:c25a:d00a:bd82
1322c19:dd:d9:dd:c25:c25a:d00a:bd83/1282c19:dd:d9:dd:c25:c25a:d00a:bd83
1332c19:dd:d9:dd:c25:c25a:d00a:bd84/1282c19:dd:d9:dd:c25:c25a:d00a:bd84
1342c19:dd:d9:dd:c25:c25a:d00a:bd85/1282c19:dd:d9:dd:c25:c25a:d00a:bd85
1352c19:dd:d9:dd:c25:c25a:d00a:bd86/1282c19:dd:d9:dd:c25:c25a:d00a:bd86
1362c19:dd:d9:dd:c25:c25a:d00a:bd87/1282c19:dd:d9:dd:c25:c25a:d00a:bd87
1372c19:dd:d9:dd:c25:c25a:d00a:bd88/1282c19:dd:d9:dd:c25:c25a:d00a:bd88
1382c19:dd:d9:dd:c25:c25a:d00a:bd89/1282c19:dd:d9:dd:c25:c25a:d00a:bd89
1392c19:dd:d9:dd:c25:c25a:d00a:bd8a/1282c19:dd:d9:dd:c25:c25a:d00a:bd8a
1402c19:dd:d9:dd:c25:c25a:d00a:bd8b/1282c19:dd:d9:dd:c25:c25a:d00a:bd8b
1412c19:dd:d9:dd:c25:c25a:d00a:bd8c/1282c19:dd:d9:dd:c25:c25a:d00a:bd8c
1422c19:dd:d9:dd:c25:c25a:d00a:bd8d/1282c19:dd:d9:dd:c25:c25a:d00a:bd8d
1432c19:dd:d9:dd:c25:c25a:d00a:bd8e/1282c19:dd:d9:dd:c25:c25a:d00a:bd8e
1442c19:dd:d9:dd:c25:c25a:d00a:bd8f/1282c19:dd:d9:dd:c25:c25a:d00a:bd8f
1452c19:dd:d9:dd:c25:c25a:d00a:bd90/1282c19:dd:d9:dd:c25:c25a:d00a:bd90
1462c19:dd:d9:dd:c25:c25a:d00a:bd91/1282c19:dd:d9:dd:c25:c25a:d00a:bd91
1472c19:dd:d9:dd:c25:c25a:d00a:bd92/1282c19:dd:d9:dd:c25:c25a:d00a:bd92
1482c19:dd:d9:dd:c25:c25a:d00a:bd93/1282c19:dd:d9:dd:c25:c25a:d00a:bd93
1492c19:dd:d9:dd:c25:c25a:d00a:bd94/1282c19:dd:d9:dd:c25:c25a:d00a:bd94
1502c19:dd:d9:dd:c25:c25a:d00a:bd95/1282c19:dd:d9:dd:c25:c25a:d00a:bd95
1512c19:dd:d9:dd:c25:c25a:d00a:bd96/1282c19:dd:d9:dd:c25:c25a:d00a:bd96
1522c19:dd:d9:dd:c25:c25a:d00a:bd97/1282c19:dd:d9:dd:c25:c25a:d00a:bd97
1532c19:dd:d9:dd:c25:c25a:d00a:bd98/1282c19:dd:d9:dd:c25:c25a:d00a:bd98
1542c19:dd:d9:dd:c25:c25a:d00a:bd99/1282c19:dd:d9:dd:c25:c25a:d00a:bd99
1552c19:dd:d9:dd:c25:c25a:d00a:bd9a/1282c19:dd:d9:dd:c25:c25a:d00a:bd9a
1562c19:dd:d9:dd:c25:c25a:d00a:bd9b/1282c19:dd:d9:dd:c25:c25a:d00a:bd9b
1572c19:dd:d9:dd:c25:c25a:d00a:bd9c/1282c19:dd:d9:dd:c25:c25a:d00a:bd9c
1582c19:dd:d9:dd:c25:c25a:d00a:bd9d/1282c19:dd:d9:dd:c25:c25a:d00a:bd9d
1592c19:dd:d9:dd:c25:c25a:d00a:bd9e/1282c19:dd:d9:dd:c25:c25a:d00a:bd9e
1602c19:dd:d9:dd:c25:c25a:d00a:bd9f/1282c19:dd:d9:dd:c25:c25a:d00a:bd9f
1612c19:dd:d9:dd:c25:c25a:d00a:bda0/1282c19:dd:d9:dd:c25:c25a:d00a:bda0
1622c19:dd:d9:dd:c25:c25a:d00a:bda1/1282c19:dd:d9:dd:c25:c25a:d00a:bda1
1632c19:dd:d9:dd:c25:c25a:d00a:bda2/1282c19:dd:d9:dd:c25:c25a:d00a:bda2
1642c19:dd:d9:dd:c25:c25a:d00a:bda3/1282c19:dd:d9:dd:c25:c25a:d00a:bda3
1652c19:dd:d9:dd:c25:c25a:d00a:bda4/1282c19:dd:d9:dd:c25:c25a:d00a:bda4
1662c19:dd:d9:dd:c25:c25a:d00a:bda5/1282c19:dd:d9:dd:c25:c25a:d00a:bda5
1672c19:dd:d9:dd:c25:c25a:d00a:bda6/1282c19:dd:d9:dd:c25:c25a:d00a:bda6
1682c19:dd:d9:dd:c25:c25a:d00a:bda7/1282c19:dd:d9:dd:c25:c25a:d00a:bda7
1692c19:dd:d9:dd:c25:c25a:d00a:bda8/1282c19:dd:d9:dd:c25:c25a:d00a:bda8
1702c19:dd:d9:dd:c25:c25a:d00a:bda9/1282c19:dd:d9:dd:c25:c25a:d00a:bda9
1712c19:dd:d9:dd:c25:c25a:d00a:bdaa/1282c19:dd:d9:dd:c25:c25a:d00a:bdaa
1722c19:dd:d9:dd:c25:c25a:d00a:bdab/1282c19:dd:d9:dd:c25:c25a:d00a:bdab
1732c19:dd:d9:dd:c25:c25a:d00a:bdac/1282c19:dd:d9:dd:c25:c25a:d00a:bdac
1742c19:dd:d9:dd:c25:c25a:d00a:bdad/1282c19:dd:d9:dd:c25:c25a:d00a:bdad
1752c19:dd:d9:dd:c25:c25a:d00a:bdae/1282c19:dd:d9:dd:c25:c25a:d00a:bdae
1762c19:dd:d9:dd:c25:c25a:d00a:bdaf/1282c19:dd:d9:dd:c25:c25a:d00a:bdaf
1772c19:dd:d9:dd:c25:c25a:d00a:bdb0/1282c19:dd:d9:dd:c25:c25a:d00a:bdb0
1782c19:dd:d9:dd:c25:c25a:d00a:bdb1/1282c19:dd:d9:dd:c25:c25a:d00a:bdb1
1792c19:dd:d9:dd:c25:c25a:d00a:bdb2/1282c19:dd:d9:dd:c25:c25a:d00a:bdb2
1802c19:dd:d9:dd:c25:c25a:d00a:bdb3/1282c19:dd:d9:dd:c25:c25a:d00a:bdb3
1812c19:dd:d9:dd:c25:c25a:d00a:bdb4/1282c19:dd:d9:dd:c25:c25a:d00a:bdb4
1822c19:dd:d9:dd:c25:c25a:d00a:bdb5/1282c19:dd:d9:dd:c25:c25a:d00a:bdb5
1832c19:dd:d9:dd:c25:c25a:d00a:bdb6/1282c19:dd:d9:dd:c25:c25a:d00a:bdb6
1842c19:dd:d9:dd:c25:c25a:d00a:bdb7/1282c19:dd:d9:dd:c25:c25a:d00a:bdb7
1852c19:dd:d9:dd:c25:c25a:d00a:bdb8/1282c19:dd:d9:dd:c25:c25a:d00a:bdb8
1862c19:dd:d9:dd:c25:c25a:d00a:bdb9/1282c19:dd:d9:dd:c25:c25a:d00a:bdb9
1872c19:dd:d9:dd:c25:c25a:d00a:bdba/1282c19:dd:d9:dd:c25:c25a:d00a:bdba
1882c19:dd:d9:dd:c25:c25a:d00a:bdbb/1282c19:dd:d9:dd:c25:c25a:d00a:bdbb
1892c19:dd:d9:dd:c25:c25a:d00a:bdbc/1282c19:dd:d9:dd:c25:c25a:d00a:bdbc
1902c19:dd:d9:dd:c25:c25a:d00a:bdbd/1282c19:dd:d9:dd:c25:c25a:d00a:bdbd
1912c19:dd:d9:dd:c25:c25a:d00a:bdbe/1282c19:dd:d9:dd:c25:c25a:d00a:bdbe
1922c19:dd:d9:dd:c25:c25a:d00a:bdbf/1282c19:dd:d9:dd:c25:c25a:d00a:bdbf
1932c19:dd:d9:dd:c25:c25a:d00a:bdc0/1282c19:dd:d9:dd:c25:c25a:d00a:bdc0
1942c19:dd:d9:dd:c25:c25a:d00a:bdc1/1282c19:dd:d9:dd:c25:c25a:d00a:bdc1
1952c19:dd:d9:dd:c25:c25a:d00a:bdc2/1282c19:dd:d9:dd:c25:c25a:d00a:bdc2
1962c19:dd:d9:dd:c25:c25a:d00a:bdc3/1282c19:dd:d9:dd:c25:c25a:d00a:bdc3
1972c19:dd:d9:dd:c25:c25a:d00a:bdc4/1282c19:dd:d9:dd:c25:c25a:d00a:bdc4
1982c19:dd:d9:dd:c25:c25a:d00a:bdc5/1282c19:dd:d9:dd:c25:c25a:d00a:bdc5
1992c19:dd:d9:dd:c25:c25a:d00a:bdc6/1282c19:dd:d9:dd:c25:c25a:d00a:bdc6
2002c19:dd:d9:dd:c25:c25a:d00a:bdc7/1282c19:dd:d9:dd:c25:c25a:d00a:bdc7
2012c19:dd:d9:dd:c25:c25a:d00a:bdc8/1282c19:dd:d9:dd:c25:c25a:d00a:bdc8
2022c19:dd:d9:dd:c25:c25a:d00a:bdc9/1282c19:dd:d9:dd:c25:c25a:d00a:bdc9
2032c19:dd:d9:dd:c25:c25a:d00a:bdca/1282c19:dd:d9:dd:c25:c25a:d00a:bdca
2042c19:dd:d9:dd:c25:c25a:d00a:bdcb/1282c19:dd:d9:dd:c25:c25a:d00a:bdcb
2052c19:dd:d9:dd:c25:c25a:d00a:bdcc/1282c19:dd:d9:dd:c25:c25a:d00a:bdcc
2062c19:dd:d9:dd:c25:c25a:d00a:bdcd/1282c19:dd:d9:dd:c25:c25a:d00a:bdcd
2072c19:dd:d9:dd:c25:c25a:d00a:bdce/1282c19:dd:d9:dd:c25:c25a:d00a:bdce
2082c19:dd:d9:dd:c25:c25a:d00a:bdcf/1282c19:dd:d9:dd:c25:c25a:d00a:bdcf
2092c19:dd:d9:dd:c25:c25a:d00a:bdd0/1282c19:dd:d9:dd:c25:c25a:d00a:bdd0
2102c19:dd:d9:dd:c25:c25a:d00a:bdd1/1282c19:dd:d9:dd:c25:c25a:d00a:bdd1
2112c19:dd:d9:dd:c25:c25a:d00a:bdd2/1282c19:dd:d9:dd:c25:c25a:d00a:bdd2
2122c19:dd:d9:dd:c25:c25a:d00a:bdd3/1282c19:dd:d9:dd:c25:c25a:d00a:bdd3
2132c19:dd:d9:dd:c25:c25a:d00a:bdd4/1282c19:dd:d9:dd:c25:c25a:d00a:bdd4
2142c19:dd:d9:dd:c25:c25a:d00a:bdd5/1282c19:dd:d9:dd:c25:c25a:d00a:bdd5
2152c19:dd:d9:dd:c25:c25a:d00a:bdd6/1282c19:dd:d9:dd:c25:c25a:d00a:bdd6
2162c19:dd:d9:dd:c25:c25a:d00a:bdd7/1282c19:dd:d9:dd:c25:c25a:d00a:bdd7
2172c19:dd:d9:dd:c25:c25a:d00a:bdd8/1282c19:dd:d9:dd:c25:c25a:d00a:bdd8
2182c19:dd:d9:dd:c25:c25a:d00a:bdd9/1282c19:dd:d9:dd:c25:c25a:d00a:bdd9
2192c19:dd:d9:dd:c25:c25a:d00a:bdda/1282c19:dd:d9:dd:c25:c25a:d00a:bdda
2202c19:dd:d9:dd:c25:c25a:d00a:bddb/1282c19:dd:d9:dd:c25:c25a:d00a:bddb
2212c19:dd:d9:dd:c25:c25a:d00a:bddc/1282c19:dd:d9:dd:c25:c25a:d00a:bddc
2222c19:dd:d9:dd:c25:c25a:d00a:bddd/1282c19:dd:d9:dd:c25:c25a:d00a:bddd
2232c19:dd:d9:dd:c25:c25a:d00a:bdde/1282c19:dd:d9:dd:c25:c25a:d00a:bdde
2242c19:dd:d9:dd:c25:c25a:d00a:bddf/1282c19:dd:d9:dd:c25:c25a:d00a:bddf
2252c19:dd:d9:dd:c25:c25a:d00a:bde0/1282c19:dd:d9:dd:c25:c25a:d00a:bde0
2262c19:dd:d9:dd:c25:c25a:d00a:bde1/1282c19:dd:d9:dd:c25:c25a:d00a:bde1
2272c19:dd:d9:dd:c25:c25a:d00a:bde2/1282c19:dd:d9:dd:c25:c25a:d00a:bde2
2282c19:dd:d9:dd:c25:c25a:d00a:bde3/1282c19:dd:d9:dd:c25:c25a:d00a:bde3
2292c19:dd:d9:dd:c25:c25a:d00a:bde4/1282c19:dd:d9:dd:c25:c25a:d00a:bde4
2302c19:dd:d9:dd:c25:c25a:d00a:bde5/1282c19:dd:d9:dd:c25:c25a:d00a:bde5
2312c19:dd:d9:dd:c25:c25a:d00a:bde6/1282c19:dd:d9:dd:c25:c25a:d00a:bde6
2322c19:dd:d9:dd:c25:c25a:d00a:bde7/1282c19:dd:d9:dd:c25:c25a:d00a:bde7
2332c19:dd:d9:dd:c25:c25a:d00a:bde8/1282c19:dd:d9:dd:c25:c25a:d00a:bde8
2342c19:dd:d9:dd:c25:c25a:d00a:bde9/1282c19:dd:d9:dd:c25:c25a:d00a:bde9
2352c19:dd:d9:dd:c25:c25a:d00a:bdea/1282c19:dd:d9:dd:c25:c25a:d00a:bdea
2362c19:dd:d9:dd:c25:c25a:d00a:bdeb/1282c19:dd:d9:dd:c25:c25a:d00a:bdeb
2372c19:dd:d9:dd:c25:c25a:d00a:bdec/1282c19:dd:d9:dd:c25:c25a:d00a:bdec
2382c19:dd:d9:dd:c25:c25a:d00a:bded/1282c19:dd:d9:dd:c25:c25a:d00a:bded
2392c19:dd:d9:dd:c25:c25a:d00a:bdee/1282c19:dd:d9:dd:c25:c25a:d00a:bdee
2402c19:dd:d9:dd:c25:c25a:d00a:bdef/1282c19:dd:d9:dd:c25:c25a:d00a:bdef
2412c19:dd:d9:dd:c25:c25a:d00a:bdf0/1282c19:dd:d9:dd:c25:c25a:d00a:bdf0
2422c19:dd:d9:dd:c25:c25a:d00a:bdf1/1282c19:dd:d9:dd:c25:c25a:d00a:bdf1
2432c19:dd:d9:dd:c25:c25a:d00a:bdf2/1282c19:dd:d9:dd:c25:c25a:d00a:bdf2
2442c19:dd:d9:dd:c25:c25a:d00a:bdf3/1282c19:dd:d9:dd:c25:c25a:d00a:bdf3
2452c19:dd:d9:dd:c25:c25a:d00a:bdf4/1282c19:dd:d9:dd:c25:c25a:d00a:bdf4
2462c19:dd:d9:dd:c25:c25a:d00a:bdf5/1282c19:dd:d9:dd:c25:c25a:d00a:bdf5
2472c19:dd:d9:dd:c25:c25a:d00a:bdf6/1282c19:dd:d9:dd:c25:c25a:d00a:bdf6
2482c19:dd:d9:dd:c25:c25a:d00a:bdf7/1282c19:dd:d9:dd:c25:c25a:d00a:bdf7
2492c19:dd:d9:dd:c25:c25a:d00a:bdf8/1282c19:dd:d9:dd:c25:c25a:d00a:bdf8
2502c19:dd:d9:dd:c25:c25a:d00a:bdf9/1282c19:dd:d9:dd:c25:c25a:d00a:bdf9
2512c19:dd:d9:dd:c25:c25a:d00a:bdfa/1282c19:dd:d9:dd:c25:c25a:d00a:bdfa
2522c19:dd:d9:dd:c25:c25a:d00a:bdfb/1282c19:dd:d9:dd:c25:c25a:d00a:bdfb
2532c19:dd:d9:dd:c25:c25a:d00a:bdfc/1282c19:dd:d9:dd:c25:c25a:d00a:bdfc
2542c19:dd:d9:dd:c25:c25a:d00a:bdfd/1282c19:dd:d9:dd:c25:c25a:d00a:bdfd
2552c19:dd:d9:dd:c25:c25a:d00a:bdfe/1282c19:dd:d9:dd:c25:c25a:d00a:bdfe
2562c19:dd:d9:dd:c25:c25a:d00a:bdff/1282c19:dd:d9:dd:c25:c25a:d00a:bdff

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.