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:c25:c25:dd:dd:dd:7200/120
First address
2c19:dd:c25:c25:dd:dd:dd:7200
Last address
2c19:dd:c25:c25:dd:dd:dd:72ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:0c25:0c25:00dd:00dd:00dd:7200
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
2.7.d.d.0.0.d.d.0.0.d.d.0.0.5.2.c.0.5.2.c.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:c25:c25:dd:dd:dd:7200/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:c25:c25:dd:dd:dd:7200/1282c19:dd:c25:c25:dd:dd:dd:7200
22c19:dd:c25:c25:dd:dd:dd:7201/1282c19:dd:c25:c25:dd:dd:dd:7201
32c19:dd:c25:c25:dd:dd:dd:7202/1282c19:dd:c25:c25:dd:dd:dd:7202
42c19:dd:c25:c25:dd:dd:dd:7203/1282c19:dd:c25:c25:dd:dd:dd:7203
52c19:dd:c25:c25:dd:dd:dd:7204/1282c19:dd:c25:c25:dd:dd:dd:7204
62c19:dd:c25:c25:dd:dd:dd:7205/1282c19:dd:c25:c25:dd:dd:dd:7205
72c19:dd:c25:c25:dd:dd:dd:7206/1282c19:dd:c25:c25:dd:dd:dd:7206
82c19:dd:c25:c25:dd:dd:dd:7207/1282c19:dd:c25:c25:dd:dd:dd:7207
92c19:dd:c25:c25:dd:dd:dd:7208/1282c19:dd:c25:c25:dd:dd:dd:7208
102c19:dd:c25:c25:dd:dd:dd:7209/1282c19:dd:c25:c25:dd:dd:dd:7209
112c19:dd:c25:c25:dd:dd:dd:720a/1282c19:dd:c25:c25:dd:dd:dd:720a
122c19:dd:c25:c25:dd:dd:dd:720b/1282c19:dd:c25:c25:dd:dd:dd:720b
132c19:dd:c25:c25:dd:dd:dd:720c/1282c19:dd:c25:c25:dd:dd:dd:720c
142c19:dd:c25:c25:dd:dd:dd:720d/1282c19:dd:c25:c25:dd:dd:dd:720d
152c19:dd:c25:c25:dd:dd:dd:720e/1282c19:dd:c25:c25:dd:dd:dd:720e
162c19:dd:c25:c25:dd:dd:dd:720f/1282c19:dd:c25:c25:dd:dd:dd:720f
172c19:dd:c25:c25:dd:dd:dd:7210/1282c19:dd:c25:c25:dd:dd:dd:7210
182c19:dd:c25:c25:dd:dd:dd:7211/1282c19:dd:c25:c25:dd:dd:dd:7211
192c19:dd:c25:c25:dd:dd:dd:7212/1282c19:dd:c25:c25:dd:dd:dd:7212
202c19:dd:c25:c25:dd:dd:dd:7213/1282c19:dd:c25:c25:dd:dd:dd:7213
212c19:dd:c25:c25:dd:dd:dd:7214/1282c19:dd:c25:c25:dd:dd:dd:7214
222c19:dd:c25:c25:dd:dd:dd:7215/1282c19:dd:c25:c25:dd:dd:dd:7215
232c19:dd:c25:c25:dd:dd:dd:7216/1282c19:dd:c25:c25:dd:dd:dd:7216
242c19:dd:c25:c25:dd:dd:dd:7217/1282c19:dd:c25:c25:dd:dd:dd:7217
252c19:dd:c25:c25:dd:dd:dd:7218/1282c19:dd:c25:c25:dd:dd:dd:7218
262c19:dd:c25:c25:dd:dd:dd:7219/1282c19:dd:c25:c25:dd:dd:dd:7219
272c19:dd:c25:c25:dd:dd:dd:721a/1282c19:dd:c25:c25:dd:dd:dd:721a
282c19:dd:c25:c25:dd:dd:dd:721b/1282c19:dd:c25:c25:dd:dd:dd:721b
292c19:dd:c25:c25:dd:dd:dd:721c/1282c19:dd:c25:c25:dd:dd:dd:721c
302c19:dd:c25:c25:dd:dd:dd:721d/1282c19:dd:c25:c25:dd:dd:dd:721d
312c19:dd:c25:c25:dd:dd:dd:721e/1282c19:dd:c25:c25:dd:dd:dd:721e
322c19:dd:c25:c25:dd:dd:dd:721f/1282c19:dd:c25:c25:dd:dd:dd:721f
332c19:dd:c25:c25:dd:dd:dd:7220/1282c19:dd:c25:c25:dd:dd:dd:7220
342c19:dd:c25:c25:dd:dd:dd:7221/1282c19:dd:c25:c25:dd:dd:dd:7221
352c19:dd:c25:c25:dd:dd:dd:7222/1282c19:dd:c25:c25:dd:dd:dd:7222
362c19:dd:c25:c25:dd:dd:dd:7223/1282c19:dd:c25:c25:dd:dd:dd:7223
372c19:dd:c25:c25:dd:dd:dd:7224/1282c19:dd:c25:c25:dd:dd:dd:7224
382c19:dd:c25:c25:dd:dd:dd:7225/1282c19:dd:c25:c25:dd:dd:dd:7225
392c19:dd:c25:c25:dd:dd:dd:7226/1282c19:dd:c25:c25:dd:dd:dd:7226
402c19:dd:c25:c25:dd:dd:dd:7227/1282c19:dd:c25:c25:dd:dd:dd:7227
412c19:dd:c25:c25:dd:dd:dd:7228/1282c19:dd:c25:c25:dd:dd:dd:7228
422c19:dd:c25:c25:dd:dd:dd:7229/1282c19:dd:c25:c25:dd:dd:dd:7229
432c19:dd:c25:c25:dd:dd:dd:722a/1282c19:dd:c25:c25:dd:dd:dd:722a
442c19:dd:c25:c25:dd:dd:dd:722b/1282c19:dd:c25:c25:dd:dd:dd:722b
452c19:dd:c25:c25:dd:dd:dd:722c/1282c19:dd:c25:c25:dd:dd:dd:722c
462c19:dd:c25:c25:dd:dd:dd:722d/1282c19:dd:c25:c25:dd:dd:dd:722d
472c19:dd:c25:c25:dd:dd:dd:722e/1282c19:dd:c25:c25:dd:dd:dd:722e
482c19:dd:c25:c25:dd:dd:dd:722f/1282c19:dd:c25:c25:dd:dd:dd:722f
492c19:dd:c25:c25:dd:dd:dd:7230/1282c19:dd:c25:c25:dd:dd:dd:7230
502c19:dd:c25:c25:dd:dd:dd:7231/1282c19:dd:c25:c25:dd:dd:dd:7231
512c19:dd:c25:c25:dd:dd:dd:7232/1282c19:dd:c25:c25:dd:dd:dd:7232
522c19:dd:c25:c25:dd:dd:dd:7233/1282c19:dd:c25:c25:dd:dd:dd:7233
532c19:dd:c25:c25:dd:dd:dd:7234/1282c19:dd:c25:c25:dd:dd:dd:7234
542c19:dd:c25:c25:dd:dd:dd:7235/1282c19:dd:c25:c25:dd:dd:dd:7235
552c19:dd:c25:c25:dd:dd:dd:7236/1282c19:dd:c25:c25:dd:dd:dd:7236
562c19:dd:c25:c25:dd:dd:dd:7237/1282c19:dd:c25:c25:dd:dd:dd:7237
572c19:dd:c25:c25:dd:dd:dd:7238/1282c19:dd:c25:c25:dd:dd:dd:7238
582c19:dd:c25:c25:dd:dd:dd:7239/1282c19:dd:c25:c25:dd:dd:dd:7239
592c19:dd:c25:c25:dd:dd:dd:723a/1282c19:dd:c25:c25:dd:dd:dd:723a
602c19:dd:c25:c25:dd:dd:dd:723b/1282c19:dd:c25:c25:dd:dd:dd:723b
612c19:dd:c25:c25:dd:dd:dd:723c/1282c19:dd:c25:c25:dd:dd:dd:723c
622c19:dd:c25:c25:dd:dd:dd:723d/1282c19:dd:c25:c25:dd:dd:dd:723d
632c19:dd:c25:c25:dd:dd:dd:723e/1282c19:dd:c25:c25:dd:dd:dd:723e
642c19:dd:c25:c25:dd:dd:dd:723f/1282c19:dd:c25:c25:dd:dd:dd:723f
652c19:dd:c25:c25:dd:dd:dd:7240/1282c19:dd:c25:c25:dd:dd:dd:7240
662c19:dd:c25:c25:dd:dd:dd:7241/1282c19:dd:c25:c25:dd:dd:dd:7241
672c19:dd:c25:c25:dd:dd:dd:7242/1282c19:dd:c25:c25:dd:dd:dd:7242
682c19:dd:c25:c25:dd:dd:dd:7243/1282c19:dd:c25:c25:dd:dd:dd:7243
692c19:dd:c25:c25:dd:dd:dd:7244/1282c19:dd:c25:c25:dd:dd:dd:7244
702c19:dd:c25:c25:dd:dd:dd:7245/1282c19:dd:c25:c25:dd:dd:dd:7245
712c19:dd:c25:c25:dd:dd:dd:7246/1282c19:dd:c25:c25:dd:dd:dd:7246
722c19:dd:c25:c25:dd:dd:dd:7247/1282c19:dd:c25:c25:dd:dd:dd:7247
732c19:dd:c25:c25:dd:dd:dd:7248/1282c19:dd:c25:c25:dd:dd:dd:7248
742c19:dd:c25:c25:dd:dd:dd:7249/1282c19:dd:c25:c25:dd:dd:dd:7249
752c19:dd:c25:c25:dd:dd:dd:724a/1282c19:dd:c25:c25:dd:dd:dd:724a
762c19:dd:c25:c25:dd:dd:dd:724b/1282c19:dd:c25:c25:dd:dd:dd:724b
772c19:dd:c25:c25:dd:dd:dd:724c/1282c19:dd:c25:c25:dd:dd:dd:724c
782c19:dd:c25:c25:dd:dd:dd:724d/1282c19:dd:c25:c25:dd:dd:dd:724d
792c19:dd:c25:c25:dd:dd:dd:724e/1282c19:dd:c25:c25:dd:dd:dd:724e
802c19:dd:c25:c25:dd:dd:dd:724f/1282c19:dd:c25:c25:dd:dd:dd:724f
812c19:dd:c25:c25:dd:dd:dd:7250/1282c19:dd:c25:c25:dd:dd:dd:7250
822c19:dd:c25:c25:dd:dd:dd:7251/1282c19:dd:c25:c25:dd:dd:dd:7251
832c19:dd:c25:c25:dd:dd:dd:7252/1282c19:dd:c25:c25:dd:dd:dd:7252
842c19:dd:c25:c25:dd:dd:dd:7253/1282c19:dd:c25:c25:dd:dd:dd:7253
852c19:dd:c25:c25:dd:dd:dd:7254/1282c19:dd:c25:c25:dd:dd:dd:7254
862c19:dd:c25:c25:dd:dd:dd:7255/1282c19:dd:c25:c25:dd:dd:dd:7255
872c19:dd:c25:c25:dd:dd:dd:7256/1282c19:dd:c25:c25:dd:dd:dd:7256
882c19:dd:c25:c25:dd:dd:dd:7257/1282c19:dd:c25:c25:dd:dd:dd:7257
892c19:dd:c25:c25:dd:dd:dd:7258/1282c19:dd:c25:c25:dd:dd:dd:7258
902c19:dd:c25:c25:dd:dd:dd:7259/1282c19:dd:c25:c25:dd:dd:dd:7259
912c19:dd:c25:c25:dd:dd:dd:725a/1282c19:dd:c25:c25:dd:dd:dd:725a
922c19:dd:c25:c25:dd:dd:dd:725b/1282c19:dd:c25:c25:dd:dd:dd:725b
932c19:dd:c25:c25:dd:dd:dd:725c/1282c19:dd:c25:c25:dd:dd:dd:725c
942c19:dd:c25:c25:dd:dd:dd:725d/1282c19:dd:c25:c25:dd:dd:dd:725d
952c19:dd:c25:c25:dd:dd:dd:725e/1282c19:dd:c25:c25:dd:dd:dd:725e
962c19:dd:c25:c25:dd:dd:dd:725f/1282c19:dd:c25:c25:dd:dd:dd:725f
972c19:dd:c25:c25:dd:dd:dd:7260/1282c19:dd:c25:c25:dd:dd:dd:7260
982c19:dd:c25:c25:dd:dd:dd:7261/1282c19:dd:c25:c25:dd:dd:dd:7261
992c19:dd:c25:c25:dd:dd:dd:7262/1282c19:dd:c25:c25:dd:dd:dd:7262
1002c19:dd:c25:c25:dd:dd:dd:7263/1282c19:dd:c25:c25:dd:dd:dd:7263
1012c19:dd:c25:c25:dd:dd:dd:7264/1282c19:dd:c25:c25:dd:dd:dd:7264
1022c19:dd:c25:c25:dd:dd:dd:7265/1282c19:dd:c25:c25:dd:dd:dd:7265
1032c19:dd:c25:c25:dd:dd:dd:7266/1282c19:dd:c25:c25:dd:dd:dd:7266
1042c19:dd:c25:c25:dd:dd:dd:7267/1282c19:dd:c25:c25:dd:dd:dd:7267
1052c19:dd:c25:c25:dd:dd:dd:7268/1282c19:dd:c25:c25:dd:dd:dd:7268
1062c19:dd:c25:c25:dd:dd:dd:7269/1282c19:dd:c25:c25:dd:dd:dd:7269
1072c19:dd:c25:c25:dd:dd:dd:726a/1282c19:dd:c25:c25:dd:dd:dd:726a
1082c19:dd:c25:c25:dd:dd:dd:726b/1282c19:dd:c25:c25:dd:dd:dd:726b
1092c19:dd:c25:c25:dd:dd:dd:726c/1282c19:dd:c25:c25:dd:dd:dd:726c
1102c19:dd:c25:c25:dd:dd:dd:726d/1282c19:dd:c25:c25:dd:dd:dd:726d
1112c19:dd:c25:c25:dd:dd:dd:726e/1282c19:dd:c25:c25:dd:dd:dd:726e
1122c19:dd:c25:c25:dd:dd:dd:726f/1282c19:dd:c25:c25:dd:dd:dd:726f
1132c19:dd:c25:c25:dd:dd:dd:7270/1282c19:dd:c25:c25:dd:dd:dd:7270
1142c19:dd:c25:c25:dd:dd:dd:7271/1282c19:dd:c25:c25:dd:dd:dd:7271
1152c19:dd:c25:c25:dd:dd:dd:7272/1282c19:dd:c25:c25:dd:dd:dd:7272
1162c19:dd:c25:c25:dd:dd:dd:7273/1282c19:dd:c25:c25:dd:dd:dd:7273
1172c19:dd:c25:c25:dd:dd:dd:7274/1282c19:dd:c25:c25:dd:dd:dd:7274
1182c19:dd:c25:c25:dd:dd:dd:7275/1282c19:dd:c25:c25:dd:dd:dd:7275
1192c19:dd:c25:c25:dd:dd:dd:7276/1282c19:dd:c25:c25:dd:dd:dd:7276
1202c19:dd:c25:c25:dd:dd:dd:7277/1282c19:dd:c25:c25:dd:dd:dd:7277
1212c19:dd:c25:c25:dd:dd:dd:7278/1282c19:dd:c25:c25:dd:dd:dd:7278
1222c19:dd:c25:c25:dd:dd:dd:7279/1282c19:dd:c25:c25:dd:dd:dd:7279
1232c19:dd:c25:c25:dd:dd:dd:727a/1282c19:dd:c25:c25:dd:dd:dd:727a
1242c19:dd:c25:c25:dd:dd:dd:727b/1282c19:dd:c25:c25:dd:dd:dd:727b
1252c19:dd:c25:c25:dd:dd:dd:727c/1282c19:dd:c25:c25:dd:dd:dd:727c
1262c19:dd:c25:c25:dd:dd:dd:727d/1282c19:dd:c25:c25:dd:dd:dd:727d
1272c19:dd:c25:c25:dd:dd:dd:727e/1282c19:dd:c25:c25:dd:dd:dd:727e
1282c19:dd:c25:c25:dd:dd:dd:727f/1282c19:dd:c25:c25:dd:dd:dd:727f
1292c19:dd:c25:c25:dd:dd:dd:7280/1282c19:dd:c25:c25:dd:dd:dd:7280
1302c19:dd:c25:c25:dd:dd:dd:7281/1282c19:dd:c25:c25:dd:dd:dd:7281
1312c19:dd:c25:c25:dd:dd:dd:7282/1282c19:dd:c25:c25:dd:dd:dd:7282
1322c19:dd:c25:c25:dd:dd:dd:7283/1282c19:dd:c25:c25:dd:dd:dd:7283
1332c19:dd:c25:c25:dd:dd:dd:7284/1282c19:dd:c25:c25:dd:dd:dd:7284
1342c19:dd:c25:c25:dd:dd:dd:7285/1282c19:dd:c25:c25:dd:dd:dd:7285
1352c19:dd:c25:c25:dd:dd:dd:7286/1282c19:dd:c25:c25:dd:dd:dd:7286
1362c19:dd:c25:c25:dd:dd:dd:7287/1282c19:dd:c25:c25:dd:dd:dd:7287
1372c19:dd:c25:c25:dd:dd:dd:7288/1282c19:dd:c25:c25:dd:dd:dd:7288
1382c19:dd:c25:c25:dd:dd:dd:7289/1282c19:dd:c25:c25:dd:dd:dd:7289
1392c19:dd:c25:c25:dd:dd:dd:728a/1282c19:dd:c25:c25:dd:dd:dd:728a
1402c19:dd:c25:c25:dd:dd:dd:728b/1282c19:dd:c25:c25:dd:dd:dd:728b
1412c19:dd:c25:c25:dd:dd:dd:728c/1282c19:dd:c25:c25:dd:dd:dd:728c
1422c19:dd:c25:c25:dd:dd:dd:728d/1282c19:dd:c25:c25:dd:dd:dd:728d
1432c19:dd:c25:c25:dd:dd:dd:728e/1282c19:dd:c25:c25:dd:dd:dd:728e
1442c19:dd:c25:c25:dd:dd:dd:728f/1282c19:dd:c25:c25:dd:dd:dd:728f
1452c19:dd:c25:c25:dd:dd:dd:7290/1282c19:dd:c25:c25:dd:dd:dd:7290
1462c19:dd:c25:c25:dd:dd:dd:7291/1282c19:dd:c25:c25:dd:dd:dd:7291
1472c19:dd:c25:c25:dd:dd:dd:7292/1282c19:dd:c25:c25:dd:dd:dd:7292
1482c19:dd:c25:c25:dd:dd:dd:7293/1282c19:dd:c25:c25:dd:dd:dd:7293
1492c19:dd:c25:c25:dd:dd:dd:7294/1282c19:dd:c25:c25:dd:dd:dd:7294
1502c19:dd:c25:c25:dd:dd:dd:7295/1282c19:dd:c25:c25:dd:dd:dd:7295
1512c19:dd:c25:c25:dd:dd:dd:7296/1282c19:dd:c25:c25:dd:dd:dd:7296
1522c19:dd:c25:c25:dd:dd:dd:7297/1282c19:dd:c25:c25:dd:dd:dd:7297
1532c19:dd:c25:c25:dd:dd:dd:7298/1282c19:dd:c25:c25:dd:dd:dd:7298
1542c19:dd:c25:c25:dd:dd:dd:7299/1282c19:dd:c25:c25:dd:dd:dd:7299
1552c19:dd:c25:c25:dd:dd:dd:729a/1282c19:dd:c25:c25:dd:dd:dd:729a
1562c19:dd:c25:c25:dd:dd:dd:729b/1282c19:dd:c25:c25:dd:dd:dd:729b
1572c19:dd:c25:c25:dd:dd:dd:729c/1282c19:dd:c25:c25:dd:dd:dd:729c
1582c19:dd:c25:c25:dd:dd:dd:729d/1282c19:dd:c25:c25:dd:dd:dd:729d
1592c19:dd:c25:c25:dd:dd:dd:729e/1282c19:dd:c25:c25:dd:dd:dd:729e
1602c19:dd:c25:c25:dd:dd:dd:729f/1282c19:dd:c25:c25:dd:dd:dd:729f
1612c19:dd:c25:c25:dd:dd:dd:72a0/1282c19:dd:c25:c25:dd:dd:dd:72a0
1622c19:dd:c25:c25:dd:dd:dd:72a1/1282c19:dd:c25:c25:dd:dd:dd:72a1
1632c19:dd:c25:c25:dd:dd:dd:72a2/1282c19:dd:c25:c25:dd:dd:dd:72a2
1642c19:dd:c25:c25:dd:dd:dd:72a3/1282c19:dd:c25:c25:dd:dd:dd:72a3
1652c19:dd:c25:c25:dd:dd:dd:72a4/1282c19:dd:c25:c25:dd:dd:dd:72a4
1662c19:dd:c25:c25:dd:dd:dd:72a5/1282c19:dd:c25:c25:dd:dd:dd:72a5
1672c19:dd:c25:c25:dd:dd:dd:72a6/1282c19:dd:c25:c25:dd:dd:dd:72a6
1682c19:dd:c25:c25:dd:dd:dd:72a7/1282c19:dd:c25:c25:dd:dd:dd:72a7
1692c19:dd:c25:c25:dd:dd:dd:72a8/1282c19:dd:c25:c25:dd:dd:dd:72a8
1702c19:dd:c25:c25:dd:dd:dd:72a9/1282c19:dd:c25:c25:dd:dd:dd:72a9
1712c19:dd:c25:c25:dd:dd:dd:72aa/1282c19:dd:c25:c25:dd:dd:dd:72aa
1722c19:dd:c25:c25:dd:dd:dd:72ab/1282c19:dd:c25:c25:dd:dd:dd:72ab
1732c19:dd:c25:c25:dd:dd:dd:72ac/1282c19:dd:c25:c25:dd:dd:dd:72ac
1742c19:dd:c25:c25:dd:dd:dd:72ad/1282c19:dd:c25:c25:dd:dd:dd:72ad
1752c19:dd:c25:c25:dd:dd:dd:72ae/1282c19:dd:c25:c25:dd:dd:dd:72ae
1762c19:dd:c25:c25:dd:dd:dd:72af/1282c19:dd:c25:c25:dd:dd:dd:72af
1772c19:dd:c25:c25:dd:dd:dd:72b0/1282c19:dd:c25:c25:dd:dd:dd:72b0
1782c19:dd:c25:c25:dd:dd:dd:72b1/1282c19:dd:c25:c25:dd:dd:dd:72b1
1792c19:dd:c25:c25:dd:dd:dd:72b2/1282c19:dd:c25:c25:dd:dd:dd:72b2
1802c19:dd:c25:c25:dd:dd:dd:72b3/1282c19:dd:c25:c25:dd:dd:dd:72b3
1812c19:dd:c25:c25:dd:dd:dd:72b4/1282c19:dd:c25:c25:dd:dd:dd:72b4
1822c19:dd:c25:c25:dd:dd:dd:72b5/1282c19:dd:c25:c25:dd:dd:dd:72b5
1832c19:dd:c25:c25:dd:dd:dd:72b6/1282c19:dd:c25:c25:dd:dd:dd:72b6
1842c19:dd:c25:c25:dd:dd:dd:72b7/1282c19:dd:c25:c25:dd:dd:dd:72b7
1852c19:dd:c25:c25:dd:dd:dd:72b8/1282c19:dd:c25:c25:dd:dd:dd:72b8
1862c19:dd:c25:c25:dd:dd:dd:72b9/1282c19:dd:c25:c25:dd:dd:dd:72b9
1872c19:dd:c25:c25:dd:dd:dd:72ba/1282c19:dd:c25:c25:dd:dd:dd:72ba
1882c19:dd:c25:c25:dd:dd:dd:72bb/1282c19:dd:c25:c25:dd:dd:dd:72bb
1892c19:dd:c25:c25:dd:dd:dd:72bc/1282c19:dd:c25:c25:dd:dd:dd:72bc
1902c19:dd:c25:c25:dd:dd:dd:72bd/1282c19:dd:c25:c25:dd:dd:dd:72bd
1912c19:dd:c25:c25:dd:dd:dd:72be/1282c19:dd:c25:c25:dd:dd:dd:72be
1922c19:dd:c25:c25:dd:dd:dd:72bf/1282c19:dd:c25:c25:dd:dd:dd:72bf
1932c19:dd:c25:c25:dd:dd:dd:72c0/1282c19:dd:c25:c25:dd:dd:dd:72c0
1942c19:dd:c25:c25:dd:dd:dd:72c1/1282c19:dd:c25:c25:dd:dd:dd:72c1
1952c19:dd:c25:c25:dd:dd:dd:72c2/1282c19:dd:c25:c25:dd:dd:dd:72c2
1962c19:dd:c25:c25:dd:dd:dd:72c3/1282c19:dd:c25:c25:dd:dd:dd:72c3
1972c19:dd:c25:c25:dd:dd:dd:72c4/1282c19:dd:c25:c25:dd:dd:dd:72c4
1982c19:dd:c25:c25:dd:dd:dd:72c5/1282c19:dd:c25:c25:dd:dd:dd:72c5
1992c19:dd:c25:c25:dd:dd:dd:72c6/1282c19:dd:c25:c25:dd:dd:dd:72c6
2002c19:dd:c25:c25:dd:dd:dd:72c7/1282c19:dd:c25:c25:dd:dd:dd:72c7
2012c19:dd:c25:c25:dd:dd:dd:72c8/1282c19:dd:c25:c25:dd:dd:dd:72c8
2022c19:dd:c25:c25:dd:dd:dd:72c9/1282c19:dd:c25:c25:dd:dd:dd:72c9
2032c19:dd:c25:c25:dd:dd:dd:72ca/1282c19:dd:c25:c25:dd:dd:dd:72ca
2042c19:dd:c25:c25:dd:dd:dd:72cb/1282c19:dd:c25:c25:dd:dd:dd:72cb
2052c19:dd:c25:c25:dd:dd:dd:72cc/1282c19:dd:c25:c25:dd:dd:dd:72cc
2062c19:dd:c25:c25:dd:dd:dd:72cd/1282c19:dd:c25:c25:dd:dd:dd:72cd
2072c19:dd:c25:c25:dd:dd:dd:72ce/1282c19:dd:c25:c25:dd:dd:dd:72ce
2082c19:dd:c25:c25:dd:dd:dd:72cf/1282c19:dd:c25:c25:dd:dd:dd:72cf
2092c19:dd:c25:c25:dd:dd:dd:72d0/1282c19:dd:c25:c25:dd:dd:dd:72d0
2102c19:dd:c25:c25:dd:dd:dd:72d1/1282c19:dd:c25:c25:dd:dd:dd:72d1
2112c19:dd:c25:c25:dd:dd:dd:72d2/1282c19:dd:c25:c25:dd:dd:dd:72d2
2122c19:dd:c25:c25:dd:dd:dd:72d3/1282c19:dd:c25:c25:dd:dd:dd:72d3
2132c19:dd:c25:c25:dd:dd:dd:72d4/1282c19:dd:c25:c25:dd:dd:dd:72d4
2142c19:dd:c25:c25:dd:dd:dd:72d5/1282c19:dd:c25:c25:dd:dd:dd:72d5
2152c19:dd:c25:c25:dd:dd:dd:72d6/1282c19:dd:c25:c25:dd:dd:dd:72d6
2162c19:dd:c25:c25:dd:dd:dd:72d7/1282c19:dd:c25:c25:dd:dd:dd:72d7
2172c19:dd:c25:c25:dd:dd:dd:72d8/1282c19:dd:c25:c25:dd:dd:dd:72d8
2182c19:dd:c25:c25:dd:dd:dd:72d9/1282c19:dd:c25:c25:dd:dd:dd:72d9
2192c19:dd:c25:c25:dd:dd:dd:72da/1282c19:dd:c25:c25:dd:dd:dd:72da
2202c19:dd:c25:c25:dd:dd:dd:72db/1282c19:dd:c25:c25:dd:dd:dd:72db
2212c19:dd:c25:c25:dd:dd:dd:72dc/1282c19:dd:c25:c25:dd:dd:dd:72dc
2222c19:dd:c25:c25:dd:dd:dd:72dd/1282c19:dd:c25:c25:dd:dd:dd:72dd
2232c19:dd:c25:c25:dd:dd:dd:72de/1282c19:dd:c25:c25:dd:dd:dd:72de
2242c19:dd:c25:c25:dd:dd:dd:72df/1282c19:dd:c25:c25:dd:dd:dd:72df
2252c19:dd:c25:c25:dd:dd:dd:72e0/1282c19:dd:c25:c25:dd:dd:dd:72e0
2262c19:dd:c25:c25:dd:dd:dd:72e1/1282c19:dd:c25:c25:dd:dd:dd:72e1
2272c19:dd:c25:c25:dd:dd:dd:72e2/1282c19:dd:c25:c25:dd:dd:dd:72e2
2282c19:dd:c25:c25:dd:dd:dd:72e3/1282c19:dd:c25:c25:dd:dd:dd:72e3
2292c19:dd:c25:c25:dd:dd:dd:72e4/1282c19:dd:c25:c25:dd:dd:dd:72e4
2302c19:dd:c25:c25:dd:dd:dd:72e5/1282c19:dd:c25:c25:dd:dd:dd:72e5
2312c19:dd:c25:c25:dd:dd:dd:72e6/1282c19:dd:c25:c25:dd:dd:dd:72e6
2322c19:dd:c25:c25:dd:dd:dd:72e7/1282c19:dd:c25:c25:dd:dd:dd:72e7
2332c19:dd:c25:c25:dd:dd:dd:72e8/1282c19:dd:c25:c25:dd:dd:dd:72e8
2342c19:dd:c25:c25:dd:dd:dd:72e9/1282c19:dd:c25:c25:dd:dd:dd:72e9
2352c19:dd:c25:c25:dd:dd:dd:72ea/1282c19:dd:c25:c25:dd:dd:dd:72ea
2362c19:dd:c25:c25:dd:dd:dd:72eb/1282c19:dd:c25:c25:dd:dd:dd:72eb
2372c19:dd:c25:c25:dd:dd:dd:72ec/1282c19:dd:c25:c25:dd:dd:dd:72ec
2382c19:dd:c25:c25:dd:dd:dd:72ed/1282c19:dd:c25:c25:dd:dd:dd:72ed
2392c19:dd:c25:c25:dd:dd:dd:72ee/1282c19:dd:c25:c25:dd:dd:dd:72ee
2402c19:dd:c25:c25:dd:dd:dd:72ef/1282c19:dd:c25:c25:dd:dd:dd:72ef
2412c19:dd:c25:c25:dd:dd:dd:72f0/1282c19:dd:c25:c25:dd:dd:dd:72f0
2422c19:dd:c25:c25:dd:dd:dd:72f1/1282c19:dd:c25:c25:dd:dd:dd:72f1
2432c19:dd:c25:c25:dd:dd:dd:72f2/1282c19:dd:c25:c25:dd:dd:dd:72f2
2442c19:dd:c25:c25:dd:dd:dd:72f3/1282c19:dd:c25:c25:dd:dd:dd:72f3
2452c19:dd:c25:c25:dd:dd:dd:72f4/1282c19:dd:c25:c25:dd:dd:dd:72f4
2462c19:dd:c25:c25:dd:dd:dd:72f5/1282c19:dd:c25:c25:dd:dd:dd:72f5
2472c19:dd:c25:c25:dd:dd:dd:72f6/1282c19:dd:c25:c25:dd:dd:dd:72f6
2482c19:dd:c25:c25:dd:dd:dd:72f7/1282c19:dd:c25:c25:dd:dd:dd:72f7
2492c19:dd:c25:c25:dd:dd:dd:72f8/1282c19:dd:c25:c25:dd:dd:dd:72f8
2502c19:dd:c25:c25:dd:dd:dd:72f9/1282c19:dd:c25:c25:dd:dd:dd:72f9
2512c19:dd:c25:c25:dd:dd:dd:72fa/1282c19:dd:c25:c25:dd:dd:dd:72fa
2522c19:dd:c25:c25:dd:dd:dd:72fb/1282c19:dd:c25:c25:dd:dd:dd:72fb
2532c19:dd:c25:c25:dd:dd:dd:72fc/1282c19:dd:c25:c25:dd:dd:dd:72fc
2542c19:dd:c25:c25:dd:dd:dd:72fd/1282c19:dd:c25:c25:dd:dd:dd:72fd
2552c19:dd:c25:c25:dd:dd:dd:72fe/1282c19:dd:c25:c25:dd:dd:dd:72fe
2562c19:dd:c25:c25:dd:dd:dd:72ff/1282c19:dd:c25:c25:dd:dd:dd:72ff

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.