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:ddfc:c200/120
First address
2c19:dd:d9:dd:c25:c25:ddfc:c200
Last address
2c19:dd:d9:dd:c25:c25:ddfc:c2ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:ddfc:c200
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
2.c.c.f.d.d.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:ddfc:c200/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:ddfc:c200/1282c19:dd:d9:dd:c25:c25:ddfc:c200
22c19:dd:d9:dd:c25:c25:ddfc:c201/1282c19:dd:d9:dd:c25:c25:ddfc:c201
32c19:dd:d9:dd:c25:c25:ddfc:c202/1282c19:dd:d9:dd:c25:c25:ddfc:c202
42c19:dd:d9:dd:c25:c25:ddfc:c203/1282c19:dd:d9:dd:c25:c25:ddfc:c203
52c19:dd:d9:dd:c25:c25:ddfc:c204/1282c19:dd:d9:dd:c25:c25:ddfc:c204
62c19:dd:d9:dd:c25:c25:ddfc:c205/1282c19:dd:d9:dd:c25:c25:ddfc:c205
72c19:dd:d9:dd:c25:c25:ddfc:c206/1282c19:dd:d9:dd:c25:c25:ddfc:c206
82c19:dd:d9:dd:c25:c25:ddfc:c207/1282c19:dd:d9:dd:c25:c25:ddfc:c207
92c19:dd:d9:dd:c25:c25:ddfc:c208/1282c19:dd:d9:dd:c25:c25:ddfc:c208
102c19:dd:d9:dd:c25:c25:ddfc:c209/1282c19:dd:d9:dd:c25:c25:ddfc:c209
112c19:dd:d9:dd:c25:c25:ddfc:c20a/1282c19:dd:d9:dd:c25:c25:ddfc:c20a
122c19:dd:d9:dd:c25:c25:ddfc:c20b/1282c19:dd:d9:dd:c25:c25:ddfc:c20b
132c19:dd:d9:dd:c25:c25:ddfc:c20c/1282c19:dd:d9:dd:c25:c25:ddfc:c20c
142c19:dd:d9:dd:c25:c25:ddfc:c20d/1282c19:dd:d9:dd:c25:c25:ddfc:c20d
152c19:dd:d9:dd:c25:c25:ddfc:c20e/1282c19:dd:d9:dd:c25:c25:ddfc:c20e
162c19:dd:d9:dd:c25:c25:ddfc:c20f/1282c19:dd:d9:dd:c25:c25:ddfc:c20f
172c19:dd:d9:dd:c25:c25:ddfc:c210/1282c19:dd:d9:dd:c25:c25:ddfc:c210
182c19:dd:d9:dd:c25:c25:ddfc:c211/1282c19:dd:d9:dd:c25:c25:ddfc:c211
192c19:dd:d9:dd:c25:c25:ddfc:c212/1282c19:dd:d9:dd:c25:c25:ddfc:c212
202c19:dd:d9:dd:c25:c25:ddfc:c213/1282c19:dd:d9:dd:c25:c25:ddfc:c213
212c19:dd:d9:dd:c25:c25:ddfc:c214/1282c19:dd:d9:dd:c25:c25:ddfc:c214
222c19:dd:d9:dd:c25:c25:ddfc:c215/1282c19:dd:d9:dd:c25:c25:ddfc:c215
232c19:dd:d9:dd:c25:c25:ddfc:c216/1282c19:dd:d9:dd:c25:c25:ddfc:c216
242c19:dd:d9:dd:c25:c25:ddfc:c217/1282c19:dd:d9:dd:c25:c25:ddfc:c217
252c19:dd:d9:dd:c25:c25:ddfc:c218/1282c19:dd:d9:dd:c25:c25:ddfc:c218
262c19:dd:d9:dd:c25:c25:ddfc:c219/1282c19:dd:d9:dd:c25:c25:ddfc:c219
272c19:dd:d9:dd:c25:c25:ddfc:c21a/1282c19:dd:d9:dd:c25:c25:ddfc:c21a
282c19:dd:d9:dd:c25:c25:ddfc:c21b/1282c19:dd:d9:dd:c25:c25:ddfc:c21b
292c19:dd:d9:dd:c25:c25:ddfc:c21c/1282c19:dd:d9:dd:c25:c25:ddfc:c21c
302c19:dd:d9:dd:c25:c25:ddfc:c21d/1282c19:dd:d9:dd:c25:c25:ddfc:c21d
312c19:dd:d9:dd:c25:c25:ddfc:c21e/1282c19:dd:d9:dd:c25:c25:ddfc:c21e
322c19:dd:d9:dd:c25:c25:ddfc:c21f/1282c19:dd:d9:dd:c25:c25:ddfc:c21f
332c19:dd:d9:dd:c25:c25:ddfc:c220/1282c19:dd:d9:dd:c25:c25:ddfc:c220
342c19:dd:d9:dd:c25:c25:ddfc:c221/1282c19:dd:d9:dd:c25:c25:ddfc:c221
352c19:dd:d9:dd:c25:c25:ddfc:c222/1282c19:dd:d9:dd:c25:c25:ddfc:c222
362c19:dd:d9:dd:c25:c25:ddfc:c223/1282c19:dd:d9:dd:c25:c25:ddfc:c223
372c19:dd:d9:dd:c25:c25:ddfc:c224/1282c19:dd:d9:dd:c25:c25:ddfc:c224
382c19:dd:d9:dd:c25:c25:ddfc:c225/1282c19:dd:d9:dd:c25:c25:ddfc:c225
392c19:dd:d9:dd:c25:c25:ddfc:c226/1282c19:dd:d9:dd:c25:c25:ddfc:c226
402c19:dd:d9:dd:c25:c25:ddfc:c227/1282c19:dd:d9:dd:c25:c25:ddfc:c227
412c19:dd:d9:dd:c25:c25:ddfc:c228/1282c19:dd:d9:dd:c25:c25:ddfc:c228
422c19:dd:d9:dd:c25:c25:ddfc:c229/1282c19:dd:d9:dd:c25:c25:ddfc:c229
432c19:dd:d9:dd:c25:c25:ddfc:c22a/1282c19:dd:d9:dd:c25:c25:ddfc:c22a
442c19:dd:d9:dd:c25:c25:ddfc:c22b/1282c19:dd:d9:dd:c25:c25:ddfc:c22b
452c19:dd:d9:dd:c25:c25:ddfc:c22c/1282c19:dd:d9:dd:c25:c25:ddfc:c22c
462c19:dd:d9:dd:c25:c25:ddfc:c22d/1282c19:dd:d9:dd:c25:c25:ddfc:c22d
472c19:dd:d9:dd:c25:c25:ddfc:c22e/1282c19:dd:d9:dd:c25:c25:ddfc:c22e
482c19:dd:d9:dd:c25:c25:ddfc:c22f/1282c19:dd:d9:dd:c25:c25:ddfc:c22f
492c19:dd:d9:dd:c25:c25:ddfc:c230/1282c19:dd:d9:dd:c25:c25:ddfc:c230
502c19:dd:d9:dd:c25:c25:ddfc:c231/1282c19:dd:d9:dd:c25:c25:ddfc:c231
512c19:dd:d9:dd:c25:c25:ddfc:c232/1282c19:dd:d9:dd:c25:c25:ddfc:c232
522c19:dd:d9:dd:c25:c25:ddfc:c233/1282c19:dd:d9:dd:c25:c25:ddfc:c233
532c19:dd:d9:dd:c25:c25:ddfc:c234/1282c19:dd:d9:dd:c25:c25:ddfc:c234
542c19:dd:d9:dd:c25:c25:ddfc:c235/1282c19:dd:d9:dd:c25:c25:ddfc:c235
552c19:dd:d9:dd:c25:c25:ddfc:c236/1282c19:dd:d9:dd:c25:c25:ddfc:c236
562c19:dd:d9:dd:c25:c25:ddfc:c237/1282c19:dd:d9:dd:c25:c25:ddfc:c237
572c19:dd:d9:dd:c25:c25:ddfc:c238/1282c19:dd:d9:dd:c25:c25:ddfc:c238
582c19:dd:d9:dd:c25:c25:ddfc:c239/1282c19:dd:d9:dd:c25:c25:ddfc:c239
592c19:dd:d9:dd:c25:c25:ddfc:c23a/1282c19:dd:d9:dd:c25:c25:ddfc:c23a
602c19:dd:d9:dd:c25:c25:ddfc:c23b/1282c19:dd:d9:dd:c25:c25:ddfc:c23b
612c19:dd:d9:dd:c25:c25:ddfc:c23c/1282c19:dd:d9:dd:c25:c25:ddfc:c23c
622c19:dd:d9:dd:c25:c25:ddfc:c23d/1282c19:dd:d9:dd:c25:c25:ddfc:c23d
632c19:dd:d9:dd:c25:c25:ddfc:c23e/1282c19:dd:d9:dd:c25:c25:ddfc:c23e
642c19:dd:d9:dd:c25:c25:ddfc:c23f/1282c19:dd:d9:dd:c25:c25:ddfc:c23f
652c19:dd:d9:dd:c25:c25:ddfc:c240/1282c19:dd:d9:dd:c25:c25:ddfc:c240
662c19:dd:d9:dd:c25:c25:ddfc:c241/1282c19:dd:d9:dd:c25:c25:ddfc:c241
672c19:dd:d9:dd:c25:c25:ddfc:c242/1282c19:dd:d9:dd:c25:c25:ddfc:c242
682c19:dd:d9:dd:c25:c25:ddfc:c243/1282c19:dd:d9:dd:c25:c25:ddfc:c243
692c19:dd:d9:dd:c25:c25:ddfc:c244/1282c19:dd:d9:dd:c25:c25:ddfc:c244
702c19:dd:d9:dd:c25:c25:ddfc:c245/1282c19:dd:d9:dd:c25:c25:ddfc:c245
712c19:dd:d9:dd:c25:c25:ddfc:c246/1282c19:dd:d9:dd:c25:c25:ddfc:c246
722c19:dd:d9:dd:c25:c25:ddfc:c247/1282c19:dd:d9:dd:c25:c25:ddfc:c247
732c19:dd:d9:dd:c25:c25:ddfc:c248/1282c19:dd:d9:dd:c25:c25:ddfc:c248
742c19:dd:d9:dd:c25:c25:ddfc:c249/1282c19:dd:d9:dd:c25:c25:ddfc:c249
752c19:dd:d9:dd:c25:c25:ddfc:c24a/1282c19:dd:d9:dd:c25:c25:ddfc:c24a
762c19:dd:d9:dd:c25:c25:ddfc:c24b/1282c19:dd:d9:dd:c25:c25:ddfc:c24b
772c19:dd:d9:dd:c25:c25:ddfc:c24c/1282c19:dd:d9:dd:c25:c25:ddfc:c24c
782c19:dd:d9:dd:c25:c25:ddfc:c24d/1282c19:dd:d9:dd:c25:c25:ddfc:c24d
792c19:dd:d9:dd:c25:c25:ddfc:c24e/1282c19:dd:d9:dd:c25:c25:ddfc:c24e
802c19:dd:d9:dd:c25:c25:ddfc:c24f/1282c19:dd:d9:dd:c25:c25:ddfc:c24f
812c19:dd:d9:dd:c25:c25:ddfc:c250/1282c19:dd:d9:dd:c25:c25:ddfc:c250
822c19:dd:d9:dd:c25:c25:ddfc:c251/1282c19:dd:d9:dd:c25:c25:ddfc:c251
832c19:dd:d9:dd:c25:c25:ddfc:c252/1282c19:dd:d9:dd:c25:c25:ddfc:c252
842c19:dd:d9:dd:c25:c25:ddfc:c253/1282c19:dd:d9:dd:c25:c25:ddfc:c253
852c19:dd:d9:dd:c25:c25:ddfc:c254/1282c19:dd:d9:dd:c25:c25:ddfc:c254
862c19:dd:d9:dd:c25:c25:ddfc:c255/1282c19:dd:d9:dd:c25:c25:ddfc:c255
872c19:dd:d9:dd:c25:c25:ddfc:c256/1282c19:dd:d9:dd:c25:c25:ddfc:c256
882c19:dd:d9:dd:c25:c25:ddfc:c257/1282c19:dd:d9:dd:c25:c25:ddfc:c257
892c19:dd:d9:dd:c25:c25:ddfc:c258/1282c19:dd:d9:dd:c25:c25:ddfc:c258
902c19:dd:d9:dd:c25:c25:ddfc:c259/1282c19:dd:d9:dd:c25:c25:ddfc:c259
912c19:dd:d9:dd:c25:c25:ddfc:c25a/1282c19:dd:d9:dd:c25:c25:ddfc:c25a
922c19:dd:d9:dd:c25:c25:ddfc:c25b/1282c19:dd:d9:dd:c25:c25:ddfc:c25b
932c19:dd:d9:dd:c25:c25:ddfc:c25c/1282c19:dd:d9:dd:c25:c25:ddfc:c25c
942c19:dd:d9:dd:c25:c25:ddfc:c25d/1282c19:dd:d9:dd:c25:c25:ddfc:c25d
952c19:dd:d9:dd:c25:c25:ddfc:c25e/1282c19:dd:d9:dd:c25:c25:ddfc:c25e
962c19:dd:d9:dd:c25:c25:ddfc:c25f/1282c19:dd:d9:dd:c25:c25:ddfc:c25f
972c19:dd:d9:dd:c25:c25:ddfc:c260/1282c19:dd:d9:dd:c25:c25:ddfc:c260
982c19:dd:d9:dd:c25:c25:ddfc:c261/1282c19:dd:d9:dd:c25:c25:ddfc:c261
992c19:dd:d9:dd:c25:c25:ddfc:c262/1282c19:dd:d9:dd:c25:c25:ddfc:c262
1002c19:dd:d9:dd:c25:c25:ddfc:c263/1282c19:dd:d9:dd:c25:c25:ddfc:c263
1012c19:dd:d9:dd:c25:c25:ddfc:c264/1282c19:dd:d9:dd:c25:c25:ddfc:c264
1022c19:dd:d9:dd:c25:c25:ddfc:c265/1282c19:dd:d9:dd:c25:c25:ddfc:c265
1032c19:dd:d9:dd:c25:c25:ddfc:c266/1282c19:dd:d9:dd:c25:c25:ddfc:c266
1042c19:dd:d9:dd:c25:c25:ddfc:c267/1282c19:dd:d9:dd:c25:c25:ddfc:c267
1052c19:dd:d9:dd:c25:c25:ddfc:c268/1282c19:dd:d9:dd:c25:c25:ddfc:c268
1062c19:dd:d9:dd:c25:c25:ddfc:c269/1282c19:dd:d9:dd:c25:c25:ddfc:c269
1072c19:dd:d9:dd:c25:c25:ddfc:c26a/1282c19:dd:d9:dd:c25:c25:ddfc:c26a
1082c19:dd:d9:dd:c25:c25:ddfc:c26b/1282c19:dd:d9:dd:c25:c25:ddfc:c26b
1092c19:dd:d9:dd:c25:c25:ddfc:c26c/1282c19:dd:d9:dd:c25:c25:ddfc:c26c
1102c19:dd:d9:dd:c25:c25:ddfc:c26d/1282c19:dd:d9:dd:c25:c25:ddfc:c26d
1112c19:dd:d9:dd:c25:c25:ddfc:c26e/1282c19:dd:d9:dd:c25:c25:ddfc:c26e
1122c19:dd:d9:dd:c25:c25:ddfc:c26f/1282c19:dd:d9:dd:c25:c25:ddfc:c26f
1132c19:dd:d9:dd:c25:c25:ddfc:c270/1282c19:dd:d9:dd:c25:c25:ddfc:c270
1142c19:dd:d9:dd:c25:c25:ddfc:c271/1282c19:dd:d9:dd:c25:c25:ddfc:c271
1152c19:dd:d9:dd:c25:c25:ddfc:c272/1282c19:dd:d9:dd:c25:c25:ddfc:c272
1162c19:dd:d9:dd:c25:c25:ddfc:c273/1282c19:dd:d9:dd:c25:c25:ddfc:c273
1172c19:dd:d9:dd:c25:c25:ddfc:c274/1282c19:dd:d9:dd:c25:c25:ddfc:c274
1182c19:dd:d9:dd:c25:c25:ddfc:c275/1282c19:dd:d9:dd:c25:c25:ddfc:c275
1192c19:dd:d9:dd:c25:c25:ddfc:c276/1282c19:dd:d9:dd:c25:c25:ddfc:c276
1202c19:dd:d9:dd:c25:c25:ddfc:c277/1282c19:dd:d9:dd:c25:c25:ddfc:c277
1212c19:dd:d9:dd:c25:c25:ddfc:c278/1282c19:dd:d9:dd:c25:c25:ddfc:c278
1222c19:dd:d9:dd:c25:c25:ddfc:c279/1282c19:dd:d9:dd:c25:c25:ddfc:c279
1232c19:dd:d9:dd:c25:c25:ddfc:c27a/1282c19:dd:d9:dd:c25:c25:ddfc:c27a
1242c19:dd:d9:dd:c25:c25:ddfc:c27b/1282c19:dd:d9:dd:c25:c25:ddfc:c27b
1252c19:dd:d9:dd:c25:c25:ddfc:c27c/1282c19:dd:d9:dd:c25:c25:ddfc:c27c
1262c19:dd:d9:dd:c25:c25:ddfc:c27d/1282c19:dd:d9:dd:c25:c25:ddfc:c27d
1272c19:dd:d9:dd:c25:c25:ddfc:c27e/1282c19:dd:d9:dd:c25:c25:ddfc:c27e
1282c19:dd:d9:dd:c25:c25:ddfc:c27f/1282c19:dd:d9:dd:c25:c25:ddfc:c27f
1292c19:dd:d9:dd:c25:c25:ddfc:c280/1282c19:dd:d9:dd:c25:c25:ddfc:c280
1302c19:dd:d9:dd:c25:c25:ddfc:c281/1282c19:dd:d9:dd:c25:c25:ddfc:c281
1312c19:dd:d9:dd:c25:c25:ddfc:c282/1282c19:dd:d9:dd:c25:c25:ddfc:c282
1322c19:dd:d9:dd:c25:c25:ddfc:c283/1282c19:dd:d9:dd:c25:c25:ddfc:c283
1332c19:dd:d9:dd:c25:c25:ddfc:c284/1282c19:dd:d9:dd:c25:c25:ddfc:c284
1342c19:dd:d9:dd:c25:c25:ddfc:c285/1282c19:dd:d9:dd:c25:c25:ddfc:c285
1352c19:dd:d9:dd:c25:c25:ddfc:c286/1282c19:dd:d9:dd:c25:c25:ddfc:c286
1362c19:dd:d9:dd:c25:c25:ddfc:c287/1282c19:dd:d9:dd:c25:c25:ddfc:c287
1372c19:dd:d9:dd:c25:c25:ddfc:c288/1282c19:dd:d9:dd:c25:c25:ddfc:c288
1382c19:dd:d9:dd:c25:c25:ddfc:c289/1282c19:dd:d9:dd:c25:c25:ddfc:c289
1392c19:dd:d9:dd:c25:c25:ddfc:c28a/1282c19:dd:d9:dd:c25:c25:ddfc:c28a
1402c19:dd:d9:dd:c25:c25:ddfc:c28b/1282c19:dd:d9:dd:c25:c25:ddfc:c28b
1412c19:dd:d9:dd:c25:c25:ddfc:c28c/1282c19:dd:d9:dd:c25:c25:ddfc:c28c
1422c19:dd:d9:dd:c25:c25:ddfc:c28d/1282c19:dd:d9:dd:c25:c25:ddfc:c28d
1432c19:dd:d9:dd:c25:c25:ddfc:c28e/1282c19:dd:d9:dd:c25:c25:ddfc:c28e
1442c19:dd:d9:dd:c25:c25:ddfc:c28f/1282c19:dd:d9:dd:c25:c25:ddfc:c28f
1452c19:dd:d9:dd:c25:c25:ddfc:c290/1282c19:dd:d9:dd:c25:c25:ddfc:c290
1462c19:dd:d9:dd:c25:c25:ddfc:c291/1282c19:dd:d9:dd:c25:c25:ddfc:c291
1472c19:dd:d9:dd:c25:c25:ddfc:c292/1282c19:dd:d9:dd:c25:c25:ddfc:c292
1482c19:dd:d9:dd:c25:c25:ddfc:c293/1282c19:dd:d9:dd:c25:c25:ddfc:c293
1492c19:dd:d9:dd:c25:c25:ddfc:c294/1282c19:dd:d9:dd:c25:c25:ddfc:c294
1502c19:dd:d9:dd:c25:c25:ddfc:c295/1282c19:dd:d9:dd:c25:c25:ddfc:c295
1512c19:dd:d9:dd:c25:c25:ddfc:c296/1282c19:dd:d9:dd:c25:c25:ddfc:c296
1522c19:dd:d9:dd:c25:c25:ddfc:c297/1282c19:dd:d9:dd:c25:c25:ddfc:c297
1532c19:dd:d9:dd:c25:c25:ddfc:c298/1282c19:dd:d9:dd:c25:c25:ddfc:c298
1542c19:dd:d9:dd:c25:c25:ddfc:c299/1282c19:dd:d9:dd:c25:c25:ddfc:c299
1552c19:dd:d9:dd:c25:c25:ddfc:c29a/1282c19:dd:d9:dd:c25:c25:ddfc:c29a
1562c19:dd:d9:dd:c25:c25:ddfc:c29b/1282c19:dd:d9:dd:c25:c25:ddfc:c29b
1572c19:dd:d9:dd:c25:c25:ddfc:c29c/1282c19:dd:d9:dd:c25:c25:ddfc:c29c
1582c19:dd:d9:dd:c25:c25:ddfc:c29d/1282c19:dd:d9:dd:c25:c25:ddfc:c29d
1592c19:dd:d9:dd:c25:c25:ddfc:c29e/1282c19:dd:d9:dd:c25:c25:ddfc:c29e
1602c19:dd:d9:dd:c25:c25:ddfc:c29f/1282c19:dd:d9:dd:c25:c25:ddfc:c29f
1612c19:dd:d9:dd:c25:c25:ddfc:c2a0/1282c19:dd:d9:dd:c25:c25:ddfc:c2a0
1622c19:dd:d9:dd:c25:c25:ddfc:c2a1/1282c19:dd:d9:dd:c25:c25:ddfc:c2a1
1632c19:dd:d9:dd:c25:c25:ddfc:c2a2/1282c19:dd:d9:dd:c25:c25:ddfc:c2a2
1642c19:dd:d9:dd:c25:c25:ddfc:c2a3/1282c19:dd:d9:dd:c25:c25:ddfc:c2a3
1652c19:dd:d9:dd:c25:c25:ddfc:c2a4/1282c19:dd:d9:dd:c25:c25:ddfc:c2a4
1662c19:dd:d9:dd:c25:c25:ddfc:c2a5/1282c19:dd:d9:dd:c25:c25:ddfc:c2a5
1672c19:dd:d9:dd:c25:c25:ddfc:c2a6/1282c19:dd:d9:dd:c25:c25:ddfc:c2a6
1682c19:dd:d9:dd:c25:c25:ddfc:c2a7/1282c19:dd:d9:dd:c25:c25:ddfc:c2a7
1692c19:dd:d9:dd:c25:c25:ddfc:c2a8/1282c19:dd:d9:dd:c25:c25:ddfc:c2a8
1702c19:dd:d9:dd:c25:c25:ddfc:c2a9/1282c19:dd:d9:dd:c25:c25:ddfc:c2a9
1712c19:dd:d9:dd:c25:c25:ddfc:c2aa/1282c19:dd:d9:dd:c25:c25:ddfc:c2aa
1722c19:dd:d9:dd:c25:c25:ddfc:c2ab/1282c19:dd:d9:dd:c25:c25:ddfc:c2ab
1732c19:dd:d9:dd:c25:c25:ddfc:c2ac/1282c19:dd:d9:dd:c25:c25:ddfc:c2ac
1742c19:dd:d9:dd:c25:c25:ddfc:c2ad/1282c19:dd:d9:dd:c25:c25:ddfc:c2ad
1752c19:dd:d9:dd:c25:c25:ddfc:c2ae/1282c19:dd:d9:dd:c25:c25:ddfc:c2ae
1762c19:dd:d9:dd:c25:c25:ddfc:c2af/1282c19:dd:d9:dd:c25:c25:ddfc:c2af
1772c19:dd:d9:dd:c25:c25:ddfc:c2b0/1282c19:dd:d9:dd:c25:c25:ddfc:c2b0
1782c19:dd:d9:dd:c25:c25:ddfc:c2b1/1282c19:dd:d9:dd:c25:c25:ddfc:c2b1
1792c19:dd:d9:dd:c25:c25:ddfc:c2b2/1282c19:dd:d9:dd:c25:c25:ddfc:c2b2
1802c19:dd:d9:dd:c25:c25:ddfc:c2b3/1282c19:dd:d9:dd:c25:c25:ddfc:c2b3
1812c19:dd:d9:dd:c25:c25:ddfc:c2b4/1282c19:dd:d9:dd:c25:c25:ddfc:c2b4
1822c19:dd:d9:dd:c25:c25:ddfc:c2b5/1282c19:dd:d9:dd:c25:c25:ddfc:c2b5
1832c19:dd:d9:dd:c25:c25:ddfc:c2b6/1282c19:dd:d9:dd:c25:c25:ddfc:c2b6
1842c19:dd:d9:dd:c25:c25:ddfc:c2b7/1282c19:dd:d9:dd:c25:c25:ddfc:c2b7
1852c19:dd:d9:dd:c25:c25:ddfc:c2b8/1282c19:dd:d9:dd:c25:c25:ddfc:c2b8
1862c19:dd:d9:dd:c25:c25:ddfc:c2b9/1282c19:dd:d9:dd:c25:c25:ddfc:c2b9
1872c19:dd:d9:dd:c25:c25:ddfc:c2ba/1282c19:dd:d9:dd:c25:c25:ddfc:c2ba
1882c19:dd:d9:dd:c25:c25:ddfc:c2bb/1282c19:dd:d9:dd:c25:c25:ddfc:c2bb
1892c19:dd:d9:dd:c25:c25:ddfc:c2bc/1282c19:dd:d9:dd:c25:c25:ddfc:c2bc
1902c19:dd:d9:dd:c25:c25:ddfc:c2bd/1282c19:dd:d9:dd:c25:c25:ddfc:c2bd
1912c19:dd:d9:dd:c25:c25:ddfc:c2be/1282c19:dd:d9:dd:c25:c25:ddfc:c2be
1922c19:dd:d9:dd:c25:c25:ddfc:c2bf/1282c19:dd:d9:dd:c25:c25:ddfc:c2bf
1932c19:dd:d9:dd:c25:c25:ddfc:c2c0/1282c19:dd:d9:dd:c25:c25:ddfc:c2c0
1942c19:dd:d9:dd:c25:c25:ddfc:c2c1/1282c19:dd:d9:dd:c25:c25:ddfc:c2c1
1952c19:dd:d9:dd:c25:c25:ddfc:c2c2/1282c19:dd:d9:dd:c25:c25:ddfc:c2c2
1962c19:dd:d9:dd:c25:c25:ddfc:c2c3/1282c19:dd:d9:dd:c25:c25:ddfc:c2c3
1972c19:dd:d9:dd:c25:c25:ddfc:c2c4/1282c19:dd:d9:dd:c25:c25:ddfc:c2c4
1982c19:dd:d9:dd:c25:c25:ddfc:c2c5/1282c19:dd:d9:dd:c25:c25:ddfc:c2c5
1992c19:dd:d9:dd:c25:c25:ddfc:c2c6/1282c19:dd:d9:dd:c25:c25:ddfc:c2c6
2002c19:dd:d9:dd:c25:c25:ddfc:c2c7/1282c19:dd:d9:dd:c25:c25:ddfc:c2c7
2012c19:dd:d9:dd:c25:c25:ddfc:c2c8/1282c19:dd:d9:dd:c25:c25:ddfc:c2c8
2022c19:dd:d9:dd:c25:c25:ddfc:c2c9/1282c19:dd:d9:dd:c25:c25:ddfc:c2c9
2032c19:dd:d9:dd:c25:c25:ddfc:c2ca/1282c19:dd:d9:dd:c25:c25:ddfc:c2ca
2042c19:dd:d9:dd:c25:c25:ddfc:c2cb/1282c19:dd:d9:dd:c25:c25:ddfc:c2cb
2052c19:dd:d9:dd:c25:c25:ddfc:c2cc/1282c19:dd:d9:dd:c25:c25:ddfc:c2cc
2062c19:dd:d9:dd:c25:c25:ddfc:c2cd/1282c19:dd:d9:dd:c25:c25:ddfc:c2cd
2072c19:dd:d9:dd:c25:c25:ddfc:c2ce/1282c19:dd:d9:dd:c25:c25:ddfc:c2ce
2082c19:dd:d9:dd:c25:c25:ddfc:c2cf/1282c19:dd:d9:dd:c25:c25:ddfc:c2cf
2092c19:dd:d9:dd:c25:c25:ddfc:c2d0/1282c19:dd:d9:dd:c25:c25:ddfc:c2d0
2102c19:dd:d9:dd:c25:c25:ddfc:c2d1/1282c19:dd:d9:dd:c25:c25:ddfc:c2d1
2112c19:dd:d9:dd:c25:c25:ddfc:c2d2/1282c19:dd:d9:dd:c25:c25:ddfc:c2d2
2122c19:dd:d9:dd:c25:c25:ddfc:c2d3/1282c19:dd:d9:dd:c25:c25:ddfc:c2d3
2132c19:dd:d9:dd:c25:c25:ddfc:c2d4/1282c19:dd:d9:dd:c25:c25:ddfc:c2d4
2142c19:dd:d9:dd:c25:c25:ddfc:c2d5/1282c19:dd:d9:dd:c25:c25:ddfc:c2d5
2152c19:dd:d9:dd:c25:c25:ddfc:c2d6/1282c19:dd:d9:dd:c25:c25:ddfc:c2d6
2162c19:dd:d9:dd:c25:c25:ddfc:c2d7/1282c19:dd:d9:dd:c25:c25:ddfc:c2d7
2172c19:dd:d9:dd:c25:c25:ddfc:c2d8/1282c19:dd:d9:dd:c25:c25:ddfc:c2d8
2182c19:dd:d9:dd:c25:c25:ddfc:c2d9/1282c19:dd:d9:dd:c25:c25:ddfc:c2d9
2192c19:dd:d9:dd:c25:c25:ddfc:c2da/1282c19:dd:d9:dd:c25:c25:ddfc:c2da
2202c19:dd:d9:dd:c25:c25:ddfc:c2db/1282c19:dd:d9:dd:c25:c25:ddfc:c2db
2212c19:dd:d9:dd:c25:c25:ddfc:c2dc/1282c19:dd:d9:dd:c25:c25:ddfc:c2dc
2222c19:dd:d9:dd:c25:c25:ddfc:c2dd/1282c19:dd:d9:dd:c25:c25:ddfc:c2dd
2232c19:dd:d9:dd:c25:c25:ddfc:c2de/1282c19:dd:d9:dd:c25:c25:ddfc:c2de
2242c19:dd:d9:dd:c25:c25:ddfc:c2df/1282c19:dd:d9:dd:c25:c25:ddfc:c2df
2252c19:dd:d9:dd:c25:c25:ddfc:c2e0/1282c19:dd:d9:dd:c25:c25:ddfc:c2e0
2262c19:dd:d9:dd:c25:c25:ddfc:c2e1/1282c19:dd:d9:dd:c25:c25:ddfc:c2e1
2272c19:dd:d9:dd:c25:c25:ddfc:c2e2/1282c19:dd:d9:dd:c25:c25:ddfc:c2e2
2282c19:dd:d9:dd:c25:c25:ddfc:c2e3/1282c19:dd:d9:dd:c25:c25:ddfc:c2e3
2292c19:dd:d9:dd:c25:c25:ddfc:c2e4/1282c19:dd:d9:dd:c25:c25:ddfc:c2e4
2302c19:dd:d9:dd:c25:c25:ddfc:c2e5/1282c19:dd:d9:dd:c25:c25:ddfc:c2e5
2312c19:dd:d9:dd:c25:c25:ddfc:c2e6/1282c19:dd:d9:dd:c25:c25:ddfc:c2e6
2322c19:dd:d9:dd:c25:c25:ddfc:c2e7/1282c19:dd:d9:dd:c25:c25:ddfc:c2e7
2332c19:dd:d9:dd:c25:c25:ddfc:c2e8/1282c19:dd:d9:dd:c25:c25:ddfc:c2e8
2342c19:dd:d9:dd:c25:c25:ddfc:c2e9/1282c19:dd:d9:dd:c25:c25:ddfc:c2e9
2352c19:dd:d9:dd:c25:c25:ddfc:c2ea/1282c19:dd:d9:dd:c25:c25:ddfc:c2ea
2362c19:dd:d9:dd:c25:c25:ddfc:c2eb/1282c19:dd:d9:dd:c25:c25:ddfc:c2eb
2372c19:dd:d9:dd:c25:c25:ddfc:c2ec/1282c19:dd:d9:dd:c25:c25:ddfc:c2ec
2382c19:dd:d9:dd:c25:c25:ddfc:c2ed/1282c19:dd:d9:dd:c25:c25:ddfc:c2ed
2392c19:dd:d9:dd:c25:c25:ddfc:c2ee/1282c19:dd:d9:dd:c25:c25:ddfc:c2ee
2402c19:dd:d9:dd:c25:c25:ddfc:c2ef/1282c19:dd:d9:dd:c25:c25:ddfc:c2ef
2412c19:dd:d9:dd:c25:c25:ddfc:c2f0/1282c19:dd:d9:dd:c25:c25:ddfc:c2f0
2422c19:dd:d9:dd:c25:c25:ddfc:c2f1/1282c19:dd:d9:dd:c25:c25:ddfc:c2f1
2432c19:dd:d9:dd:c25:c25:ddfc:c2f2/1282c19:dd:d9:dd:c25:c25:ddfc:c2f2
2442c19:dd:d9:dd:c25:c25:ddfc:c2f3/1282c19:dd:d9:dd:c25:c25:ddfc:c2f3
2452c19:dd:d9:dd:c25:c25:ddfc:c2f4/1282c19:dd:d9:dd:c25:c25:ddfc:c2f4
2462c19:dd:d9:dd:c25:c25:ddfc:c2f5/1282c19:dd:d9:dd:c25:c25:ddfc:c2f5
2472c19:dd:d9:dd:c25:c25:ddfc:c2f6/1282c19:dd:d9:dd:c25:c25:ddfc:c2f6
2482c19:dd:d9:dd:c25:c25:ddfc:c2f7/1282c19:dd:d9:dd:c25:c25:ddfc:c2f7
2492c19:dd:d9:dd:c25:c25:ddfc:c2f8/1282c19:dd:d9:dd:c25:c25:ddfc:c2f8
2502c19:dd:d9:dd:c25:c25:ddfc:c2f9/1282c19:dd:d9:dd:c25:c25:ddfc:c2f9
2512c19:dd:d9:dd:c25:c25:ddfc:c2fa/1282c19:dd:d9:dd:c25:c25:ddfc:c2fa
2522c19:dd:d9:dd:c25:c25:ddfc:c2fb/1282c19:dd:d9:dd:c25:c25:ddfc:c2fb
2532c19:dd:d9:dd:c25:c25:ddfc:c2fc/1282c19:dd:d9:dd:c25:c25:ddfc:c2fc
2542c19:dd:d9:dd:c25:c25:ddfc:c2fd/1282c19:dd:d9:dd:c25:c25:ddfc:c2fd
2552c19:dd:d9:dd:c25:c25:ddfc:c2fe/1282c19:dd:d9:dd:c25:c25:ddfc:c2fe
2562c19:dd:d9:dd:c25:c25:ddfc:c2ff/1282c19:dd:d9:dd:c25:c25:ddfc:c2ff

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.