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:d9:dd:c25:c25:c00a:d000/119
First address
2c19:dd:d9:dd:c25:c25:c00a:d000
Last address
2c19:dd:d9:dd:c25:c25:c00a:d1ff
Addresses
512
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:c00a:d000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
0.d.a.0.0.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
1.d.a.0.0.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
/119 is not on a 4-bit boundary, so it takes 2 /120 zones.
Split into smaller subnets/127
/120 (2)/121 (4)/122 (8)/123 (16)/124 (32)/127 (256)/128 (512)

2c19:dd:d9:dd:c25:c25:c00a:d000/119 makes 256 subnets of /127.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:c00a:d000/1272c19:dd:d9:dd:c25:c25:c00a:d001
22c19:dd:d9:dd:c25:c25:c00a:d002/1272c19:dd:d9:dd:c25:c25:c00a:d003
32c19:dd:d9:dd:c25:c25:c00a:d004/1272c19:dd:d9:dd:c25:c25:c00a:d005
42c19:dd:d9:dd:c25:c25:c00a:d006/1272c19:dd:d9:dd:c25:c25:c00a:d007
52c19:dd:d9:dd:c25:c25:c00a:d008/1272c19:dd:d9:dd:c25:c25:c00a:d009
62c19:dd:d9:dd:c25:c25:c00a:d00a/1272c19:dd:d9:dd:c25:c25:c00a:d00b
72c19:dd:d9:dd:c25:c25:c00a:d00c/1272c19:dd:d9:dd:c25:c25:c00a:d00d
82c19:dd:d9:dd:c25:c25:c00a:d00e/1272c19:dd:d9:dd:c25:c25:c00a:d00f
92c19:dd:d9:dd:c25:c25:c00a:d010/1272c19:dd:d9:dd:c25:c25:c00a:d011
102c19:dd:d9:dd:c25:c25:c00a:d012/1272c19:dd:d9:dd:c25:c25:c00a:d013
112c19:dd:d9:dd:c25:c25:c00a:d014/1272c19:dd:d9:dd:c25:c25:c00a:d015
122c19:dd:d9:dd:c25:c25:c00a:d016/1272c19:dd:d9:dd:c25:c25:c00a:d017
132c19:dd:d9:dd:c25:c25:c00a:d018/1272c19:dd:d9:dd:c25:c25:c00a:d019
142c19:dd:d9:dd:c25:c25:c00a:d01a/1272c19:dd:d9:dd:c25:c25:c00a:d01b
152c19:dd:d9:dd:c25:c25:c00a:d01c/1272c19:dd:d9:dd:c25:c25:c00a:d01d
162c19:dd:d9:dd:c25:c25:c00a:d01e/1272c19:dd:d9:dd:c25:c25:c00a:d01f
172c19:dd:d9:dd:c25:c25:c00a:d020/1272c19:dd:d9:dd:c25:c25:c00a:d021
182c19:dd:d9:dd:c25:c25:c00a:d022/1272c19:dd:d9:dd:c25:c25:c00a:d023
192c19:dd:d9:dd:c25:c25:c00a:d024/1272c19:dd:d9:dd:c25:c25:c00a:d025
202c19:dd:d9:dd:c25:c25:c00a:d026/1272c19:dd:d9:dd:c25:c25:c00a:d027
212c19:dd:d9:dd:c25:c25:c00a:d028/1272c19:dd:d9:dd:c25:c25:c00a:d029
222c19:dd:d9:dd:c25:c25:c00a:d02a/1272c19:dd:d9:dd:c25:c25:c00a:d02b
232c19:dd:d9:dd:c25:c25:c00a:d02c/1272c19:dd:d9:dd:c25:c25:c00a:d02d
242c19:dd:d9:dd:c25:c25:c00a:d02e/1272c19:dd:d9:dd:c25:c25:c00a:d02f
252c19:dd:d9:dd:c25:c25:c00a:d030/1272c19:dd:d9:dd:c25:c25:c00a:d031
262c19:dd:d9:dd:c25:c25:c00a:d032/1272c19:dd:d9:dd:c25:c25:c00a:d033
272c19:dd:d9:dd:c25:c25:c00a:d034/1272c19:dd:d9:dd:c25:c25:c00a:d035
282c19:dd:d9:dd:c25:c25:c00a:d036/1272c19:dd:d9:dd:c25:c25:c00a:d037
292c19:dd:d9:dd:c25:c25:c00a:d038/1272c19:dd:d9:dd:c25:c25:c00a:d039
302c19:dd:d9:dd:c25:c25:c00a:d03a/1272c19:dd:d9:dd:c25:c25:c00a:d03b
312c19:dd:d9:dd:c25:c25:c00a:d03c/1272c19:dd:d9:dd:c25:c25:c00a:d03d
322c19:dd:d9:dd:c25:c25:c00a:d03e/1272c19:dd:d9:dd:c25:c25:c00a:d03f
332c19:dd:d9:dd:c25:c25:c00a:d040/1272c19:dd:d9:dd:c25:c25:c00a:d041
342c19:dd:d9:dd:c25:c25:c00a:d042/1272c19:dd:d9:dd:c25:c25:c00a:d043
352c19:dd:d9:dd:c25:c25:c00a:d044/1272c19:dd:d9:dd:c25:c25:c00a:d045
362c19:dd:d9:dd:c25:c25:c00a:d046/1272c19:dd:d9:dd:c25:c25:c00a:d047
372c19:dd:d9:dd:c25:c25:c00a:d048/1272c19:dd:d9:dd:c25:c25:c00a:d049
382c19:dd:d9:dd:c25:c25:c00a:d04a/1272c19:dd:d9:dd:c25:c25:c00a:d04b
392c19:dd:d9:dd:c25:c25:c00a:d04c/1272c19:dd:d9:dd:c25:c25:c00a:d04d
402c19:dd:d9:dd:c25:c25:c00a:d04e/1272c19:dd:d9:dd:c25:c25:c00a:d04f
412c19:dd:d9:dd:c25:c25:c00a:d050/1272c19:dd:d9:dd:c25:c25:c00a:d051
422c19:dd:d9:dd:c25:c25:c00a:d052/1272c19:dd:d9:dd:c25:c25:c00a:d053
432c19:dd:d9:dd:c25:c25:c00a:d054/1272c19:dd:d9:dd:c25:c25:c00a:d055
442c19:dd:d9:dd:c25:c25:c00a:d056/1272c19:dd:d9:dd:c25:c25:c00a:d057
452c19:dd:d9:dd:c25:c25:c00a:d058/1272c19:dd:d9:dd:c25:c25:c00a:d059
462c19:dd:d9:dd:c25:c25:c00a:d05a/1272c19:dd:d9:dd:c25:c25:c00a:d05b
472c19:dd:d9:dd:c25:c25:c00a:d05c/1272c19:dd:d9:dd:c25:c25:c00a:d05d
482c19:dd:d9:dd:c25:c25:c00a:d05e/1272c19:dd:d9:dd:c25:c25:c00a:d05f
492c19:dd:d9:dd:c25:c25:c00a:d060/1272c19:dd:d9:dd:c25:c25:c00a:d061
502c19:dd:d9:dd:c25:c25:c00a:d062/1272c19:dd:d9:dd:c25:c25:c00a:d063
512c19:dd:d9:dd:c25:c25:c00a:d064/1272c19:dd:d9:dd:c25:c25:c00a:d065
522c19:dd:d9:dd:c25:c25:c00a:d066/1272c19:dd:d9:dd:c25:c25:c00a:d067
532c19:dd:d9:dd:c25:c25:c00a:d068/1272c19:dd:d9:dd:c25:c25:c00a:d069
542c19:dd:d9:dd:c25:c25:c00a:d06a/1272c19:dd:d9:dd:c25:c25:c00a:d06b
552c19:dd:d9:dd:c25:c25:c00a:d06c/1272c19:dd:d9:dd:c25:c25:c00a:d06d
562c19:dd:d9:dd:c25:c25:c00a:d06e/1272c19:dd:d9:dd:c25:c25:c00a:d06f
572c19:dd:d9:dd:c25:c25:c00a:d070/1272c19:dd:d9:dd:c25:c25:c00a:d071
582c19:dd:d9:dd:c25:c25:c00a:d072/1272c19:dd:d9:dd:c25:c25:c00a:d073
592c19:dd:d9:dd:c25:c25:c00a:d074/1272c19:dd:d9:dd:c25:c25:c00a:d075
602c19:dd:d9:dd:c25:c25:c00a:d076/1272c19:dd:d9:dd:c25:c25:c00a:d077
612c19:dd:d9:dd:c25:c25:c00a:d078/1272c19:dd:d9:dd:c25:c25:c00a:d079
622c19:dd:d9:dd:c25:c25:c00a:d07a/1272c19:dd:d9:dd:c25:c25:c00a:d07b
632c19:dd:d9:dd:c25:c25:c00a:d07c/1272c19:dd:d9:dd:c25:c25:c00a:d07d
642c19:dd:d9:dd:c25:c25:c00a:d07e/1272c19:dd:d9:dd:c25:c25:c00a:d07f
652c19:dd:d9:dd:c25:c25:c00a:d080/1272c19:dd:d9:dd:c25:c25:c00a:d081
662c19:dd:d9:dd:c25:c25:c00a:d082/1272c19:dd:d9:dd:c25:c25:c00a:d083
672c19:dd:d9:dd:c25:c25:c00a:d084/1272c19:dd:d9:dd:c25:c25:c00a:d085
682c19:dd:d9:dd:c25:c25:c00a:d086/1272c19:dd:d9:dd:c25:c25:c00a:d087
692c19:dd:d9:dd:c25:c25:c00a:d088/1272c19:dd:d9:dd:c25:c25:c00a:d089
702c19:dd:d9:dd:c25:c25:c00a:d08a/1272c19:dd:d9:dd:c25:c25:c00a:d08b
712c19:dd:d9:dd:c25:c25:c00a:d08c/1272c19:dd:d9:dd:c25:c25:c00a:d08d
722c19:dd:d9:dd:c25:c25:c00a:d08e/1272c19:dd:d9:dd:c25:c25:c00a:d08f
732c19:dd:d9:dd:c25:c25:c00a:d090/1272c19:dd:d9:dd:c25:c25:c00a:d091
742c19:dd:d9:dd:c25:c25:c00a:d092/1272c19:dd:d9:dd:c25:c25:c00a:d093
752c19:dd:d9:dd:c25:c25:c00a:d094/1272c19:dd:d9:dd:c25:c25:c00a:d095
762c19:dd:d9:dd:c25:c25:c00a:d096/1272c19:dd:d9:dd:c25:c25:c00a:d097
772c19:dd:d9:dd:c25:c25:c00a:d098/1272c19:dd:d9:dd:c25:c25:c00a:d099
782c19:dd:d9:dd:c25:c25:c00a:d09a/1272c19:dd:d9:dd:c25:c25:c00a:d09b
792c19:dd:d9:dd:c25:c25:c00a:d09c/1272c19:dd:d9:dd:c25:c25:c00a:d09d
802c19:dd:d9:dd:c25:c25:c00a:d09e/1272c19:dd:d9:dd:c25:c25:c00a:d09f
812c19:dd:d9:dd:c25:c25:c00a:d0a0/1272c19:dd:d9:dd:c25:c25:c00a:d0a1
822c19:dd:d9:dd:c25:c25:c00a:d0a2/1272c19:dd:d9:dd:c25:c25:c00a:d0a3
832c19:dd:d9:dd:c25:c25:c00a:d0a4/1272c19:dd:d9:dd:c25:c25:c00a:d0a5
842c19:dd:d9:dd:c25:c25:c00a:d0a6/1272c19:dd:d9:dd:c25:c25:c00a:d0a7
852c19:dd:d9:dd:c25:c25:c00a:d0a8/1272c19:dd:d9:dd:c25:c25:c00a:d0a9
862c19:dd:d9:dd:c25:c25:c00a:d0aa/1272c19:dd:d9:dd:c25:c25:c00a:d0ab
872c19:dd:d9:dd:c25:c25:c00a:d0ac/1272c19:dd:d9:dd:c25:c25:c00a:d0ad
882c19:dd:d9:dd:c25:c25:c00a:d0ae/1272c19:dd:d9:dd:c25:c25:c00a:d0af
892c19:dd:d9:dd:c25:c25:c00a:d0b0/1272c19:dd:d9:dd:c25:c25:c00a:d0b1
902c19:dd:d9:dd:c25:c25:c00a:d0b2/1272c19:dd:d9:dd:c25:c25:c00a:d0b3
912c19:dd:d9:dd:c25:c25:c00a:d0b4/1272c19:dd:d9:dd:c25:c25:c00a:d0b5
922c19:dd:d9:dd:c25:c25:c00a:d0b6/1272c19:dd:d9:dd:c25:c25:c00a:d0b7
932c19:dd:d9:dd:c25:c25:c00a:d0b8/1272c19:dd:d9:dd:c25:c25:c00a:d0b9
942c19:dd:d9:dd:c25:c25:c00a:d0ba/1272c19:dd:d9:dd:c25:c25:c00a:d0bb
952c19:dd:d9:dd:c25:c25:c00a:d0bc/1272c19:dd:d9:dd:c25:c25:c00a:d0bd
962c19:dd:d9:dd:c25:c25:c00a:d0be/1272c19:dd:d9:dd:c25:c25:c00a:d0bf
972c19:dd:d9:dd:c25:c25:c00a:d0c0/1272c19:dd:d9:dd:c25:c25:c00a:d0c1
982c19:dd:d9:dd:c25:c25:c00a:d0c2/1272c19:dd:d9:dd:c25:c25:c00a:d0c3
992c19:dd:d9:dd:c25:c25:c00a:d0c4/1272c19:dd:d9:dd:c25:c25:c00a:d0c5
1002c19:dd:d9:dd:c25:c25:c00a:d0c6/1272c19:dd:d9:dd:c25:c25:c00a:d0c7
1012c19:dd:d9:dd:c25:c25:c00a:d0c8/1272c19:dd:d9:dd:c25:c25:c00a:d0c9
1022c19:dd:d9:dd:c25:c25:c00a:d0ca/1272c19:dd:d9:dd:c25:c25:c00a:d0cb
1032c19:dd:d9:dd:c25:c25:c00a:d0cc/1272c19:dd:d9:dd:c25:c25:c00a:d0cd
1042c19:dd:d9:dd:c25:c25:c00a:d0ce/1272c19:dd:d9:dd:c25:c25:c00a:d0cf
1052c19:dd:d9:dd:c25:c25:c00a:d0d0/1272c19:dd:d9:dd:c25:c25:c00a:d0d1
1062c19:dd:d9:dd:c25:c25:c00a:d0d2/1272c19:dd:d9:dd:c25:c25:c00a:d0d3
1072c19:dd:d9:dd:c25:c25:c00a:d0d4/1272c19:dd:d9:dd:c25:c25:c00a:d0d5
1082c19:dd:d9:dd:c25:c25:c00a:d0d6/1272c19:dd:d9:dd:c25:c25:c00a:d0d7
1092c19:dd:d9:dd:c25:c25:c00a:d0d8/1272c19:dd:d9:dd:c25:c25:c00a:d0d9
1102c19:dd:d9:dd:c25:c25:c00a:d0da/1272c19:dd:d9:dd:c25:c25:c00a:d0db
1112c19:dd:d9:dd:c25:c25:c00a:d0dc/1272c19:dd:d9:dd:c25:c25:c00a:d0dd
1122c19:dd:d9:dd:c25:c25:c00a:d0de/1272c19:dd:d9:dd:c25:c25:c00a:d0df
1132c19:dd:d9:dd:c25:c25:c00a:d0e0/1272c19:dd:d9:dd:c25:c25:c00a:d0e1
1142c19:dd:d9:dd:c25:c25:c00a:d0e2/1272c19:dd:d9:dd:c25:c25:c00a:d0e3
1152c19:dd:d9:dd:c25:c25:c00a:d0e4/1272c19:dd:d9:dd:c25:c25:c00a:d0e5
1162c19:dd:d9:dd:c25:c25:c00a:d0e6/1272c19:dd:d9:dd:c25:c25:c00a:d0e7
1172c19:dd:d9:dd:c25:c25:c00a:d0e8/1272c19:dd:d9:dd:c25:c25:c00a:d0e9
1182c19:dd:d9:dd:c25:c25:c00a:d0ea/1272c19:dd:d9:dd:c25:c25:c00a:d0eb
1192c19:dd:d9:dd:c25:c25:c00a:d0ec/1272c19:dd:d9:dd:c25:c25:c00a:d0ed
1202c19:dd:d9:dd:c25:c25:c00a:d0ee/1272c19:dd:d9:dd:c25:c25:c00a:d0ef
1212c19:dd:d9:dd:c25:c25:c00a:d0f0/1272c19:dd:d9:dd:c25:c25:c00a:d0f1
1222c19:dd:d9:dd:c25:c25:c00a:d0f2/1272c19:dd:d9:dd:c25:c25:c00a:d0f3
1232c19:dd:d9:dd:c25:c25:c00a:d0f4/1272c19:dd:d9:dd:c25:c25:c00a:d0f5
1242c19:dd:d9:dd:c25:c25:c00a:d0f6/1272c19:dd:d9:dd:c25:c25:c00a:d0f7
1252c19:dd:d9:dd:c25:c25:c00a:d0f8/1272c19:dd:d9:dd:c25:c25:c00a:d0f9
1262c19:dd:d9:dd:c25:c25:c00a:d0fa/1272c19:dd:d9:dd:c25:c25:c00a:d0fb
1272c19:dd:d9:dd:c25:c25:c00a:d0fc/1272c19:dd:d9:dd:c25:c25:c00a:d0fd
1282c19:dd:d9:dd:c25:c25:c00a:d0fe/1272c19:dd:d9:dd:c25:c25:c00a:d0ff
1292c19:dd:d9:dd:c25:c25:c00a:d100/1272c19:dd:d9:dd:c25:c25:c00a:d101
1302c19:dd:d9:dd:c25:c25:c00a:d102/1272c19:dd:d9:dd:c25:c25:c00a:d103
1312c19:dd:d9:dd:c25:c25:c00a:d104/1272c19:dd:d9:dd:c25:c25:c00a:d105
1322c19:dd:d9:dd:c25:c25:c00a:d106/1272c19:dd:d9:dd:c25:c25:c00a:d107
1332c19:dd:d9:dd:c25:c25:c00a:d108/1272c19:dd:d9:dd:c25:c25:c00a:d109
1342c19:dd:d9:dd:c25:c25:c00a:d10a/1272c19:dd:d9:dd:c25:c25:c00a:d10b
1352c19:dd:d9:dd:c25:c25:c00a:d10c/1272c19:dd:d9:dd:c25:c25:c00a:d10d
1362c19:dd:d9:dd:c25:c25:c00a:d10e/1272c19:dd:d9:dd:c25:c25:c00a:d10f
1372c19:dd:d9:dd:c25:c25:c00a:d110/1272c19:dd:d9:dd:c25:c25:c00a:d111
1382c19:dd:d9:dd:c25:c25:c00a:d112/1272c19:dd:d9:dd:c25:c25:c00a:d113
1392c19:dd:d9:dd:c25:c25:c00a:d114/1272c19:dd:d9:dd:c25:c25:c00a:d115
1402c19:dd:d9:dd:c25:c25:c00a:d116/1272c19:dd:d9:dd:c25:c25:c00a:d117
1412c19:dd:d9:dd:c25:c25:c00a:d118/1272c19:dd:d9:dd:c25:c25:c00a:d119
1422c19:dd:d9:dd:c25:c25:c00a:d11a/1272c19:dd:d9:dd:c25:c25:c00a:d11b
1432c19:dd:d9:dd:c25:c25:c00a:d11c/1272c19:dd:d9:dd:c25:c25:c00a:d11d
1442c19:dd:d9:dd:c25:c25:c00a:d11e/1272c19:dd:d9:dd:c25:c25:c00a:d11f
1452c19:dd:d9:dd:c25:c25:c00a:d120/1272c19:dd:d9:dd:c25:c25:c00a:d121
1462c19:dd:d9:dd:c25:c25:c00a:d122/1272c19:dd:d9:dd:c25:c25:c00a:d123
1472c19:dd:d9:dd:c25:c25:c00a:d124/1272c19:dd:d9:dd:c25:c25:c00a:d125
1482c19:dd:d9:dd:c25:c25:c00a:d126/1272c19:dd:d9:dd:c25:c25:c00a:d127
1492c19:dd:d9:dd:c25:c25:c00a:d128/1272c19:dd:d9:dd:c25:c25:c00a:d129
1502c19:dd:d9:dd:c25:c25:c00a:d12a/1272c19:dd:d9:dd:c25:c25:c00a:d12b
1512c19:dd:d9:dd:c25:c25:c00a:d12c/1272c19:dd:d9:dd:c25:c25:c00a:d12d
1522c19:dd:d9:dd:c25:c25:c00a:d12e/1272c19:dd:d9:dd:c25:c25:c00a:d12f
1532c19:dd:d9:dd:c25:c25:c00a:d130/1272c19:dd:d9:dd:c25:c25:c00a:d131
1542c19:dd:d9:dd:c25:c25:c00a:d132/1272c19:dd:d9:dd:c25:c25:c00a:d133
1552c19:dd:d9:dd:c25:c25:c00a:d134/1272c19:dd:d9:dd:c25:c25:c00a:d135
1562c19:dd:d9:dd:c25:c25:c00a:d136/1272c19:dd:d9:dd:c25:c25:c00a:d137
1572c19:dd:d9:dd:c25:c25:c00a:d138/1272c19:dd:d9:dd:c25:c25:c00a:d139
1582c19:dd:d9:dd:c25:c25:c00a:d13a/1272c19:dd:d9:dd:c25:c25:c00a:d13b
1592c19:dd:d9:dd:c25:c25:c00a:d13c/1272c19:dd:d9:dd:c25:c25:c00a:d13d
1602c19:dd:d9:dd:c25:c25:c00a:d13e/1272c19:dd:d9:dd:c25:c25:c00a:d13f
1612c19:dd:d9:dd:c25:c25:c00a:d140/1272c19:dd:d9:dd:c25:c25:c00a:d141
1622c19:dd:d9:dd:c25:c25:c00a:d142/1272c19:dd:d9:dd:c25:c25:c00a:d143
1632c19:dd:d9:dd:c25:c25:c00a:d144/1272c19:dd:d9:dd:c25:c25:c00a:d145
1642c19:dd:d9:dd:c25:c25:c00a:d146/1272c19:dd:d9:dd:c25:c25:c00a:d147
1652c19:dd:d9:dd:c25:c25:c00a:d148/1272c19:dd:d9:dd:c25:c25:c00a:d149
1662c19:dd:d9:dd:c25:c25:c00a:d14a/1272c19:dd:d9:dd:c25:c25:c00a:d14b
1672c19:dd:d9:dd:c25:c25:c00a:d14c/1272c19:dd:d9:dd:c25:c25:c00a:d14d
1682c19:dd:d9:dd:c25:c25:c00a:d14e/1272c19:dd:d9:dd:c25:c25:c00a:d14f
1692c19:dd:d9:dd:c25:c25:c00a:d150/1272c19:dd:d9:dd:c25:c25:c00a:d151
1702c19:dd:d9:dd:c25:c25:c00a:d152/1272c19:dd:d9:dd:c25:c25:c00a:d153
1712c19:dd:d9:dd:c25:c25:c00a:d154/1272c19:dd:d9:dd:c25:c25:c00a:d155
1722c19:dd:d9:dd:c25:c25:c00a:d156/1272c19:dd:d9:dd:c25:c25:c00a:d157
1732c19:dd:d9:dd:c25:c25:c00a:d158/1272c19:dd:d9:dd:c25:c25:c00a:d159
1742c19:dd:d9:dd:c25:c25:c00a:d15a/1272c19:dd:d9:dd:c25:c25:c00a:d15b
1752c19:dd:d9:dd:c25:c25:c00a:d15c/1272c19:dd:d9:dd:c25:c25:c00a:d15d
1762c19:dd:d9:dd:c25:c25:c00a:d15e/1272c19:dd:d9:dd:c25:c25:c00a:d15f
1772c19:dd:d9:dd:c25:c25:c00a:d160/1272c19:dd:d9:dd:c25:c25:c00a:d161
1782c19:dd:d9:dd:c25:c25:c00a:d162/1272c19:dd:d9:dd:c25:c25:c00a:d163
1792c19:dd:d9:dd:c25:c25:c00a:d164/1272c19:dd:d9:dd:c25:c25:c00a:d165
1802c19:dd:d9:dd:c25:c25:c00a:d166/1272c19:dd:d9:dd:c25:c25:c00a:d167
1812c19:dd:d9:dd:c25:c25:c00a:d168/1272c19:dd:d9:dd:c25:c25:c00a:d169
1822c19:dd:d9:dd:c25:c25:c00a:d16a/1272c19:dd:d9:dd:c25:c25:c00a:d16b
1832c19:dd:d9:dd:c25:c25:c00a:d16c/1272c19:dd:d9:dd:c25:c25:c00a:d16d
1842c19:dd:d9:dd:c25:c25:c00a:d16e/1272c19:dd:d9:dd:c25:c25:c00a:d16f
1852c19:dd:d9:dd:c25:c25:c00a:d170/1272c19:dd:d9:dd:c25:c25:c00a:d171
1862c19:dd:d9:dd:c25:c25:c00a:d172/1272c19:dd:d9:dd:c25:c25:c00a:d173
1872c19:dd:d9:dd:c25:c25:c00a:d174/1272c19:dd:d9:dd:c25:c25:c00a:d175
1882c19:dd:d9:dd:c25:c25:c00a:d176/1272c19:dd:d9:dd:c25:c25:c00a:d177
1892c19:dd:d9:dd:c25:c25:c00a:d178/1272c19:dd:d9:dd:c25:c25:c00a:d179
1902c19:dd:d9:dd:c25:c25:c00a:d17a/1272c19:dd:d9:dd:c25:c25:c00a:d17b
1912c19:dd:d9:dd:c25:c25:c00a:d17c/1272c19:dd:d9:dd:c25:c25:c00a:d17d
1922c19:dd:d9:dd:c25:c25:c00a:d17e/1272c19:dd:d9:dd:c25:c25:c00a:d17f
1932c19:dd:d9:dd:c25:c25:c00a:d180/1272c19:dd:d9:dd:c25:c25:c00a:d181
1942c19:dd:d9:dd:c25:c25:c00a:d182/1272c19:dd:d9:dd:c25:c25:c00a:d183
1952c19:dd:d9:dd:c25:c25:c00a:d184/1272c19:dd:d9:dd:c25:c25:c00a:d185
1962c19:dd:d9:dd:c25:c25:c00a:d186/1272c19:dd:d9:dd:c25:c25:c00a:d187
1972c19:dd:d9:dd:c25:c25:c00a:d188/1272c19:dd:d9:dd:c25:c25:c00a:d189
1982c19:dd:d9:dd:c25:c25:c00a:d18a/1272c19:dd:d9:dd:c25:c25:c00a:d18b
1992c19:dd:d9:dd:c25:c25:c00a:d18c/1272c19:dd:d9:dd:c25:c25:c00a:d18d
2002c19:dd:d9:dd:c25:c25:c00a:d18e/1272c19:dd:d9:dd:c25:c25:c00a:d18f
2012c19:dd:d9:dd:c25:c25:c00a:d190/1272c19:dd:d9:dd:c25:c25:c00a:d191
2022c19:dd:d9:dd:c25:c25:c00a:d192/1272c19:dd:d9:dd:c25:c25:c00a:d193
2032c19:dd:d9:dd:c25:c25:c00a:d194/1272c19:dd:d9:dd:c25:c25:c00a:d195
2042c19:dd:d9:dd:c25:c25:c00a:d196/1272c19:dd:d9:dd:c25:c25:c00a:d197
2052c19:dd:d9:dd:c25:c25:c00a:d198/1272c19:dd:d9:dd:c25:c25:c00a:d199
2062c19:dd:d9:dd:c25:c25:c00a:d19a/1272c19:dd:d9:dd:c25:c25:c00a:d19b
2072c19:dd:d9:dd:c25:c25:c00a:d19c/1272c19:dd:d9:dd:c25:c25:c00a:d19d
2082c19:dd:d9:dd:c25:c25:c00a:d19e/1272c19:dd:d9:dd:c25:c25:c00a:d19f
2092c19:dd:d9:dd:c25:c25:c00a:d1a0/1272c19:dd:d9:dd:c25:c25:c00a:d1a1
2102c19:dd:d9:dd:c25:c25:c00a:d1a2/1272c19:dd:d9:dd:c25:c25:c00a:d1a3
2112c19:dd:d9:dd:c25:c25:c00a:d1a4/1272c19:dd:d9:dd:c25:c25:c00a:d1a5
2122c19:dd:d9:dd:c25:c25:c00a:d1a6/1272c19:dd:d9:dd:c25:c25:c00a:d1a7
2132c19:dd:d9:dd:c25:c25:c00a:d1a8/1272c19:dd:d9:dd:c25:c25:c00a:d1a9
2142c19:dd:d9:dd:c25:c25:c00a:d1aa/1272c19:dd:d9:dd:c25:c25:c00a:d1ab
2152c19:dd:d9:dd:c25:c25:c00a:d1ac/1272c19:dd:d9:dd:c25:c25:c00a:d1ad
2162c19:dd:d9:dd:c25:c25:c00a:d1ae/1272c19:dd:d9:dd:c25:c25:c00a:d1af
2172c19:dd:d9:dd:c25:c25:c00a:d1b0/1272c19:dd:d9:dd:c25:c25:c00a:d1b1
2182c19:dd:d9:dd:c25:c25:c00a:d1b2/1272c19:dd:d9:dd:c25:c25:c00a:d1b3
2192c19:dd:d9:dd:c25:c25:c00a:d1b4/1272c19:dd:d9:dd:c25:c25:c00a:d1b5
2202c19:dd:d9:dd:c25:c25:c00a:d1b6/1272c19:dd:d9:dd:c25:c25:c00a:d1b7
2212c19:dd:d9:dd:c25:c25:c00a:d1b8/1272c19:dd:d9:dd:c25:c25:c00a:d1b9
2222c19:dd:d9:dd:c25:c25:c00a:d1ba/1272c19:dd:d9:dd:c25:c25:c00a:d1bb
2232c19:dd:d9:dd:c25:c25:c00a:d1bc/1272c19:dd:d9:dd:c25:c25:c00a:d1bd
2242c19:dd:d9:dd:c25:c25:c00a:d1be/1272c19:dd:d9:dd:c25:c25:c00a:d1bf
2252c19:dd:d9:dd:c25:c25:c00a:d1c0/1272c19:dd:d9:dd:c25:c25:c00a:d1c1
2262c19:dd:d9:dd:c25:c25:c00a:d1c2/1272c19:dd:d9:dd:c25:c25:c00a:d1c3
2272c19:dd:d9:dd:c25:c25:c00a:d1c4/1272c19:dd:d9:dd:c25:c25:c00a:d1c5
2282c19:dd:d9:dd:c25:c25:c00a:d1c6/1272c19:dd:d9:dd:c25:c25:c00a:d1c7
2292c19:dd:d9:dd:c25:c25:c00a:d1c8/1272c19:dd:d9:dd:c25:c25:c00a:d1c9
2302c19:dd:d9:dd:c25:c25:c00a:d1ca/1272c19:dd:d9:dd:c25:c25:c00a:d1cb
2312c19:dd:d9:dd:c25:c25:c00a:d1cc/1272c19:dd:d9:dd:c25:c25:c00a:d1cd
2322c19:dd:d9:dd:c25:c25:c00a:d1ce/1272c19:dd:d9:dd:c25:c25:c00a:d1cf
2332c19:dd:d9:dd:c25:c25:c00a:d1d0/1272c19:dd:d9:dd:c25:c25:c00a:d1d1
2342c19:dd:d9:dd:c25:c25:c00a:d1d2/1272c19:dd:d9:dd:c25:c25:c00a:d1d3
2352c19:dd:d9:dd:c25:c25:c00a:d1d4/1272c19:dd:d9:dd:c25:c25:c00a:d1d5
2362c19:dd:d9:dd:c25:c25:c00a:d1d6/1272c19:dd:d9:dd:c25:c25:c00a:d1d7
2372c19:dd:d9:dd:c25:c25:c00a:d1d8/1272c19:dd:d9:dd:c25:c25:c00a:d1d9
2382c19:dd:d9:dd:c25:c25:c00a:d1da/1272c19:dd:d9:dd:c25:c25:c00a:d1db
2392c19:dd:d9:dd:c25:c25:c00a:d1dc/1272c19:dd:d9:dd:c25:c25:c00a:d1dd
2402c19:dd:d9:dd:c25:c25:c00a:d1de/1272c19:dd:d9:dd:c25:c25:c00a:d1df
2412c19:dd:d9:dd:c25:c25:c00a:d1e0/1272c19:dd:d9:dd:c25:c25:c00a:d1e1
2422c19:dd:d9:dd:c25:c25:c00a:d1e2/1272c19:dd:d9:dd:c25:c25:c00a:d1e3
2432c19:dd:d9:dd:c25:c25:c00a:d1e4/1272c19:dd:d9:dd:c25:c25:c00a:d1e5
2442c19:dd:d9:dd:c25:c25:c00a:d1e6/1272c19:dd:d9:dd:c25:c25:c00a:d1e7
2452c19:dd:d9:dd:c25:c25:c00a:d1e8/1272c19:dd:d9:dd:c25:c25:c00a:d1e9
2462c19:dd:d9:dd:c25:c25:c00a:d1ea/1272c19:dd:d9:dd:c25:c25:c00a:d1eb
2472c19:dd:d9:dd:c25:c25:c00a:d1ec/1272c19:dd:d9:dd:c25:c25:c00a:d1ed
2482c19:dd:d9:dd:c25:c25:c00a:d1ee/1272c19:dd:d9:dd:c25:c25:c00a:d1ef
2492c19:dd:d9:dd:c25:c25:c00a:d1f0/1272c19:dd:d9:dd:c25:c25:c00a:d1f1
2502c19:dd:d9:dd:c25:c25:c00a:d1f2/1272c19:dd:d9:dd:c25:c25:c00a:d1f3
2512c19:dd:d9:dd:c25:c25:c00a:d1f4/1272c19:dd:d9:dd:c25:c25:c00a:d1f5
2522c19:dd:d9:dd:c25:c25:c00a:d1f6/1272c19:dd:d9:dd:c25:c25:c00a:d1f7
2532c19:dd:d9:dd:c25:c25:c00a:d1f8/1272c19:dd:d9:dd:c25:c25:c00a:d1f9
2542c19:dd:d9:dd:c25:c25:c00a:d1fa/1272c19:dd:d9:dd:c25:c25:c00a:d1fb
2552c19:dd:d9:dd:c25:c25:c00a:d1fc/1272c19:dd:d9:dd:c25:c25:c00a:d1fd
2562c19:dd:d9:dd:c25:c25:c00a:d1fe/1272c19:dd:d9:dd:c25:c25:c00a:d1ff

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.