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:c25c:400a:200/120
First address
2c19:dd:d9:dd:c25:c25c:400a:200
Last address
2c19:dd:d9:dd:c25:c25c:400a:2ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:c25c:400a:0200
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
2.0.a.0.0.4.c.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:c25c:400a:200/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25c:400a:200/1282c19:dd:d9:dd:c25:c25c:400a:200
22c19:dd:d9:dd:c25:c25c:400a:201/1282c19:dd:d9:dd:c25:c25c:400a:201
32c19:dd:d9:dd:c25:c25c:400a:202/1282c19:dd:d9:dd:c25:c25c:400a:202
42c19:dd:d9:dd:c25:c25c:400a:203/1282c19:dd:d9:dd:c25:c25c:400a:203
52c19:dd:d9:dd:c25:c25c:400a:204/1282c19:dd:d9:dd:c25:c25c:400a:204
62c19:dd:d9:dd:c25:c25c:400a:205/1282c19:dd:d9:dd:c25:c25c:400a:205
72c19:dd:d9:dd:c25:c25c:400a:206/1282c19:dd:d9:dd:c25:c25c:400a:206
82c19:dd:d9:dd:c25:c25c:400a:207/1282c19:dd:d9:dd:c25:c25c:400a:207
92c19:dd:d9:dd:c25:c25c:400a:208/1282c19:dd:d9:dd:c25:c25c:400a:208
102c19:dd:d9:dd:c25:c25c:400a:209/1282c19:dd:d9:dd:c25:c25c:400a:209
112c19:dd:d9:dd:c25:c25c:400a:20a/1282c19:dd:d9:dd:c25:c25c:400a:20a
122c19:dd:d9:dd:c25:c25c:400a:20b/1282c19:dd:d9:dd:c25:c25c:400a:20b
132c19:dd:d9:dd:c25:c25c:400a:20c/1282c19:dd:d9:dd:c25:c25c:400a:20c
142c19:dd:d9:dd:c25:c25c:400a:20d/1282c19:dd:d9:dd:c25:c25c:400a:20d
152c19:dd:d9:dd:c25:c25c:400a:20e/1282c19:dd:d9:dd:c25:c25c:400a:20e
162c19:dd:d9:dd:c25:c25c:400a:20f/1282c19:dd:d9:dd:c25:c25c:400a:20f
172c19:dd:d9:dd:c25:c25c:400a:210/1282c19:dd:d9:dd:c25:c25c:400a:210
182c19:dd:d9:dd:c25:c25c:400a:211/1282c19:dd:d9:dd:c25:c25c:400a:211
192c19:dd:d9:dd:c25:c25c:400a:212/1282c19:dd:d9:dd:c25:c25c:400a:212
202c19:dd:d9:dd:c25:c25c:400a:213/1282c19:dd:d9:dd:c25:c25c:400a:213
212c19:dd:d9:dd:c25:c25c:400a:214/1282c19:dd:d9:dd:c25:c25c:400a:214
222c19:dd:d9:dd:c25:c25c:400a:215/1282c19:dd:d9:dd:c25:c25c:400a:215
232c19:dd:d9:dd:c25:c25c:400a:216/1282c19:dd:d9:dd:c25:c25c:400a:216
242c19:dd:d9:dd:c25:c25c:400a:217/1282c19:dd:d9:dd:c25:c25c:400a:217
252c19:dd:d9:dd:c25:c25c:400a:218/1282c19:dd:d9:dd:c25:c25c:400a:218
262c19:dd:d9:dd:c25:c25c:400a:219/1282c19:dd:d9:dd:c25:c25c:400a:219
272c19:dd:d9:dd:c25:c25c:400a:21a/1282c19:dd:d9:dd:c25:c25c:400a:21a
282c19:dd:d9:dd:c25:c25c:400a:21b/1282c19:dd:d9:dd:c25:c25c:400a:21b
292c19:dd:d9:dd:c25:c25c:400a:21c/1282c19:dd:d9:dd:c25:c25c:400a:21c
302c19:dd:d9:dd:c25:c25c:400a:21d/1282c19:dd:d9:dd:c25:c25c:400a:21d
312c19:dd:d9:dd:c25:c25c:400a:21e/1282c19:dd:d9:dd:c25:c25c:400a:21e
322c19:dd:d9:dd:c25:c25c:400a:21f/1282c19:dd:d9:dd:c25:c25c:400a:21f
332c19:dd:d9:dd:c25:c25c:400a:220/1282c19:dd:d9:dd:c25:c25c:400a:220
342c19:dd:d9:dd:c25:c25c:400a:221/1282c19:dd:d9:dd:c25:c25c:400a:221
352c19:dd:d9:dd:c25:c25c:400a:222/1282c19:dd:d9:dd:c25:c25c:400a:222
362c19:dd:d9:dd:c25:c25c:400a:223/1282c19:dd:d9:dd:c25:c25c:400a:223
372c19:dd:d9:dd:c25:c25c:400a:224/1282c19:dd:d9:dd:c25:c25c:400a:224
382c19:dd:d9:dd:c25:c25c:400a:225/1282c19:dd:d9:dd:c25:c25c:400a:225
392c19:dd:d9:dd:c25:c25c:400a:226/1282c19:dd:d9:dd:c25:c25c:400a:226
402c19:dd:d9:dd:c25:c25c:400a:227/1282c19:dd:d9:dd:c25:c25c:400a:227
412c19:dd:d9:dd:c25:c25c:400a:228/1282c19:dd:d9:dd:c25:c25c:400a:228
422c19:dd:d9:dd:c25:c25c:400a:229/1282c19:dd:d9:dd:c25:c25c:400a:229
432c19:dd:d9:dd:c25:c25c:400a:22a/1282c19:dd:d9:dd:c25:c25c:400a:22a
442c19:dd:d9:dd:c25:c25c:400a:22b/1282c19:dd:d9:dd:c25:c25c:400a:22b
452c19:dd:d9:dd:c25:c25c:400a:22c/1282c19:dd:d9:dd:c25:c25c:400a:22c
462c19:dd:d9:dd:c25:c25c:400a:22d/1282c19:dd:d9:dd:c25:c25c:400a:22d
472c19:dd:d9:dd:c25:c25c:400a:22e/1282c19:dd:d9:dd:c25:c25c:400a:22e
482c19:dd:d9:dd:c25:c25c:400a:22f/1282c19:dd:d9:dd:c25:c25c:400a:22f
492c19:dd:d9:dd:c25:c25c:400a:230/1282c19:dd:d9:dd:c25:c25c:400a:230
502c19:dd:d9:dd:c25:c25c:400a:231/1282c19:dd:d9:dd:c25:c25c:400a:231
512c19:dd:d9:dd:c25:c25c:400a:232/1282c19:dd:d9:dd:c25:c25c:400a:232
522c19:dd:d9:dd:c25:c25c:400a:233/1282c19:dd:d9:dd:c25:c25c:400a:233
532c19:dd:d9:dd:c25:c25c:400a:234/1282c19:dd:d9:dd:c25:c25c:400a:234
542c19:dd:d9:dd:c25:c25c:400a:235/1282c19:dd:d9:dd:c25:c25c:400a:235
552c19:dd:d9:dd:c25:c25c:400a:236/1282c19:dd:d9:dd:c25:c25c:400a:236
562c19:dd:d9:dd:c25:c25c:400a:237/1282c19:dd:d9:dd:c25:c25c:400a:237
572c19:dd:d9:dd:c25:c25c:400a:238/1282c19:dd:d9:dd:c25:c25c:400a:238
582c19:dd:d9:dd:c25:c25c:400a:239/1282c19:dd:d9:dd:c25:c25c:400a:239
592c19:dd:d9:dd:c25:c25c:400a:23a/1282c19:dd:d9:dd:c25:c25c:400a:23a
602c19:dd:d9:dd:c25:c25c:400a:23b/1282c19:dd:d9:dd:c25:c25c:400a:23b
612c19:dd:d9:dd:c25:c25c:400a:23c/1282c19:dd:d9:dd:c25:c25c:400a:23c
622c19:dd:d9:dd:c25:c25c:400a:23d/1282c19:dd:d9:dd:c25:c25c:400a:23d
632c19:dd:d9:dd:c25:c25c:400a:23e/1282c19:dd:d9:dd:c25:c25c:400a:23e
642c19:dd:d9:dd:c25:c25c:400a:23f/1282c19:dd:d9:dd:c25:c25c:400a:23f
652c19:dd:d9:dd:c25:c25c:400a:240/1282c19:dd:d9:dd:c25:c25c:400a:240
662c19:dd:d9:dd:c25:c25c:400a:241/1282c19:dd:d9:dd:c25:c25c:400a:241
672c19:dd:d9:dd:c25:c25c:400a:242/1282c19:dd:d9:dd:c25:c25c:400a:242
682c19:dd:d9:dd:c25:c25c:400a:243/1282c19:dd:d9:dd:c25:c25c:400a:243
692c19:dd:d9:dd:c25:c25c:400a:244/1282c19:dd:d9:dd:c25:c25c:400a:244
702c19:dd:d9:dd:c25:c25c:400a:245/1282c19:dd:d9:dd:c25:c25c:400a:245
712c19:dd:d9:dd:c25:c25c:400a:246/1282c19:dd:d9:dd:c25:c25c:400a:246
722c19:dd:d9:dd:c25:c25c:400a:247/1282c19:dd:d9:dd:c25:c25c:400a:247
732c19:dd:d9:dd:c25:c25c:400a:248/1282c19:dd:d9:dd:c25:c25c:400a:248
742c19:dd:d9:dd:c25:c25c:400a:249/1282c19:dd:d9:dd:c25:c25c:400a:249
752c19:dd:d9:dd:c25:c25c:400a:24a/1282c19:dd:d9:dd:c25:c25c:400a:24a
762c19:dd:d9:dd:c25:c25c:400a:24b/1282c19:dd:d9:dd:c25:c25c:400a:24b
772c19:dd:d9:dd:c25:c25c:400a:24c/1282c19:dd:d9:dd:c25:c25c:400a:24c
782c19:dd:d9:dd:c25:c25c:400a:24d/1282c19:dd:d9:dd:c25:c25c:400a:24d
792c19:dd:d9:dd:c25:c25c:400a:24e/1282c19:dd:d9:dd:c25:c25c:400a:24e
802c19:dd:d9:dd:c25:c25c:400a:24f/1282c19:dd:d9:dd:c25:c25c:400a:24f
812c19:dd:d9:dd:c25:c25c:400a:250/1282c19:dd:d9:dd:c25:c25c:400a:250
822c19:dd:d9:dd:c25:c25c:400a:251/1282c19:dd:d9:dd:c25:c25c:400a:251
832c19:dd:d9:dd:c25:c25c:400a:252/1282c19:dd:d9:dd:c25:c25c:400a:252
842c19:dd:d9:dd:c25:c25c:400a:253/1282c19:dd:d9:dd:c25:c25c:400a:253
852c19:dd:d9:dd:c25:c25c:400a:254/1282c19:dd:d9:dd:c25:c25c:400a:254
862c19:dd:d9:dd:c25:c25c:400a:255/1282c19:dd:d9:dd:c25:c25c:400a:255
872c19:dd:d9:dd:c25:c25c:400a:256/1282c19:dd:d9:dd:c25:c25c:400a:256
882c19:dd:d9:dd:c25:c25c:400a:257/1282c19:dd:d9:dd:c25:c25c:400a:257
892c19:dd:d9:dd:c25:c25c:400a:258/1282c19:dd:d9:dd:c25:c25c:400a:258
902c19:dd:d9:dd:c25:c25c:400a:259/1282c19:dd:d9:dd:c25:c25c:400a:259
912c19:dd:d9:dd:c25:c25c:400a:25a/1282c19:dd:d9:dd:c25:c25c:400a:25a
922c19:dd:d9:dd:c25:c25c:400a:25b/1282c19:dd:d9:dd:c25:c25c:400a:25b
932c19:dd:d9:dd:c25:c25c:400a:25c/1282c19:dd:d9:dd:c25:c25c:400a:25c
942c19:dd:d9:dd:c25:c25c:400a:25d/1282c19:dd:d9:dd:c25:c25c:400a:25d
952c19:dd:d9:dd:c25:c25c:400a:25e/1282c19:dd:d9:dd:c25:c25c:400a:25e
962c19:dd:d9:dd:c25:c25c:400a:25f/1282c19:dd:d9:dd:c25:c25c:400a:25f
972c19:dd:d9:dd:c25:c25c:400a:260/1282c19:dd:d9:dd:c25:c25c:400a:260
982c19:dd:d9:dd:c25:c25c:400a:261/1282c19:dd:d9:dd:c25:c25c:400a:261
992c19:dd:d9:dd:c25:c25c:400a:262/1282c19:dd:d9:dd:c25:c25c:400a:262
1002c19:dd:d9:dd:c25:c25c:400a:263/1282c19:dd:d9:dd:c25:c25c:400a:263
1012c19:dd:d9:dd:c25:c25c:400a:264/1282c19:dd:d9:dd:c25:c25c:400a:264
1022c19:dd:d9:dd:c25:c25c:400a:265/1282c19:dd:d9:dd:c25:c25c:400a:265
1032c19:dd:d9:dd:c25:c25c:400a:266/1282c19:dd:d9:dd:c25:c25c:400a:266
1042c19:dd:d9:dd:c25:c25c:400a:267/1282c19:dd:d9:dd:c25:c25c:400a:267
1052c19:dd:d9:dd:c25:c25c:400a:268/1282c19:dd:d9:dd:c25:c25c:400a:268
1062c19:dd:d9:dd:c25:c25c:400a:269/1282c19:dd:d9:dd:c25:c25c:400a:269
1072c19:dd:d9:dd:c25:c25c:400a:26a/1282c19:dd:d9:dd:c25:c25c:400a:26a
1082c19:dd:d9:dd:c25:c25c:400a:26b/1282c19:dd:d9:dd:c25:c25c:400a:26b
1092c19:dd:d9:dd:c25:c25c:400a:26c/1282c19:dd:d9:dd:c25:c25c:400a:26c
1102c19:dd:d9:dd:c25:c25c:400a:26d/1282c19:dd:d9:dd:c25:c25c:400a:26d
1112c19:dd:d9:dd:c25:c25c:400a:26e/1282c19:dd:d9:dd:c25:c25c:400a:26e
1122c19:dd:d9:dd:c25:c25c:400a:26f/1282c19:dd:d9:dd:c25:c25c:400a:26f
1132c19:dd:d9:dd:c25:c25c:400a:270/1282c19:dd:d9:dd:c25:c25c:400a:270
1142c19:dd:d9:dd:c25:c25c:400a:271/1282c19:dd:d9:dd:c25:c25c:400a:271
1152c19:dd:d9:dd:c25:c25c:400a:272/1282c19:dd:d9:dd:c25:c25c:400a:272
1162c19:dd:d9:dd:c25:c25c:400a:273/1282c19:dd:d9:dd:c25:c25c:400a:273
1172c19:dd:d9:dd:c25:c25c:400a:274/1282c19:dd:d9:dd:c25:c25c:400a:274
1182c19:dd:d9:dd:c25:c25c:400a:275/1282c19:dd:d9:dd:c25:c25c:400a:275
1192c19:dd:d9:dd:c25:c25c:400a:276/1282c19:dd:d9:dd:c25:c25c:400a:276
1202c19:dd:d9:dd:c25:c25c:400a:277/1282c19:dd:d9:dd:c25:c25c:400a:277
1212c19:dd:d9:dd:c25:c25c:400a:278/1282c19:dd:d9:dd:c25:c25c:400a:278
1222c19:dd:d9:dd:c25:c25c:400a:279/1282c19:dd:d9:dd:c25:c25c:400a:279
1232c19:dd:d9:dd:c25:c25c:400a:27a/1282c19:dd:d9:dd:c25:c25c:400a:27a
1242c19:dd:d9:dd:c25:c25c:400a:27b/1282c19:dd:d9:dd:c25:c25c:400a:27b
1252c19:dd:d9:dd:c25:c25c:400a:27c/1282c19:dd:d9:dd:c25:c25c:400a:27c
1262c19:dd:d9:dd:c25:c25c:400a:27d/1282c19:dd:d9:dd:c25:c25c:400a:27d
1272c19:dd:d9:dd:c25:c25c:400a:27e/1282c19:dd:d9:dd:c25:c25c:400a:27e
1282c19:dd:d9:dd:c25:c25c:400a:27f/1282c19:dd:d9:dd:c25:c25c:400a:27f
1292c19:dd:d9:dd:c25:c25c:400a:280/1282c19:dd:d9:dd:c25:c25c:400a:280
1302c19:dd:d9:dd:c25:c25c:400a:281/1282c19:dd:d9:dd:c25:c25c:400a:281
1312c19:dd:d9:dd:c25:c25c:400a:282/1282c19:dd:d9:dd:c25:c25c:400a:282
1322c19:dd:d9:dd:c25:c25c:400a:283/1282c19:dd:d9:dd:c25:c25c:400a:283
1332c19:dd:d9:dd:c25:c25c:400a:284/1282c19:dd:d9:dd:c25:c25c:400a:284
1342c19:dd:d9:dd:c25:c25c:400a:285/1282c19:dd:d9:dd:c25:c25c:400a:285
1352c19:dd:d9:dd:c25:c25c:400a:286/1282c19:dd:d9:dd:c25:c25c:400a:286
1362c19:dd:d9:dd:c25:c25c:400a:287/1282c19:dd:d9:dd:c25:c25c:400a:287
1372c19:dd:d9:dd:c25:c25c:400a:288/1282c19:dd:d9:dd:c25:c25c:400a:288
1382c19:dd:d9:dd:c25:c25c:400a:289/1282c19:dd:d9:dd:c25:c25c:400a:289
1392c19:dd:d9:dd:c25:c25c:400a:28a/1282c19:dd:d9:dd:c25:c25c:400a:28a
1402c19:dd:d9:dd:c25:c25c:400a:28b/1282c19:dd:d9:dd:c25:c25c:400a:28b
1412c19:dd:d9:dd:c25:c25c:400a:28c/1282c19:dd:d9:dd:c25:c25c:400a:28c
1422c19:dd:d9:dd:c25:c25c:400a:28d/1282c19:dd:d9:dd:c25:c25c:400a:28d
1432c19:dd:d9:dd:c25:c25c:400a:28e/1282c19:dd:d9:dd:c25:c25c:400a:28e
1442c19:dd:d9:dd:c25:c25c:400a:28f/1282c19:dd:d9:dd:c25:c25c:400a:28f
1452c19:dd:d9:dd:c25:c25c:400a:290/1282c19:dd:d9:dd:c25:c25c:400a:290
1462c19:dd:d9:dd:c25:c25c:400a:291/1282c19:dd:d9:dd:c25:c25c:400a:291
1472c19:dd:d9:dd:c25:c25c:400a:292/1282c19:dd:d9:dd:c25:c25c:400a:292
1482c19:dd:d9:dd:c25:c25c:400a:293/1282c19:dd:d9:dd:c25:c25c:400a:293
1492c19:dd:d9:dd:c25:c25c:400a:294/1282c19:dd:d9:dd:c25:c25c:400a:294
1502c19:dd:d9:dd:c25:c25c:400a:295/1282c19:dd:d9:dd:c25:c25c:400a:295
1512c19:dd:d9:dd:c25:c25c:400a:296/1282c19:dd:d9:dd:c25:c25c:400a:296
1522c19:dd:d9:dd:c25:c25c:400a:297/1282c19:dd:d9:dd:c25:c25c:400a:297
1532c19:dd:d9:dd:c25:c25c:400a:298/1282c19:dd:d9:dd:c25:c25c:400a:298
1542c19:dd:d9:dd:c25:c25c:400a:299/1282c19:dd:d9:dd:c25:c25c:400a:299
1552c19:dd:d9:dd:c25:c25c:400a:29a/1282c19:dd:d9:dd:c25:c25c:400a:29a
1562c19:dd:d9:dd:c25:c25c:400a:29b/1282c19:dd:d9:dd:c25:c25c:400a:29b
1572c19:dd:d9:dd:c25:c25c:400a:29c/1282c19:dd:d9:dd:c25:c25c:400a:29c
1582c19:dd:d9:dd:c25:c25c:400a:29d/1282c19:dd:d9:dd:c25:c25c:400a:29d
1592c19:dd:d9:dd:c25:c25c:400a:29e/1282c19:dd:d9:dd:c25:c25c:400a:29e
1602c19:dd:d9:dd:c25:c25c:400a:29f/1282c19:dd:d9:dd:c25:c25c:400a:29f
1612c19:dd:d9:dd:c25:c25c:400a:2a0/1282c19:dd:d9:dd:c25:c25c:400a:2a0
1622c19:dd:d9:dd:c25:c25c:400a:2a1/1282c19:dd:d9:dd:c25:c25c:400a:2a1
1632c19:dd:d9:dd:c25:c25c:400a:2a2/1282c19:dd:d9:dd:c25:c25c:400a:2a2
1642c19:dd:d9:dd:c25:c25c:400a:2a3/1282c19:dd:d9:dd:c25:c25c:400a:2a3
1652c19:dd:d9:dd:c25:c25c:400a:2a4/1282c19:dd:d9:dd:c25:c25c:400a:2a4
1662c19:dd:d9:dd:c25:c25c:400a:2a5/1282c19:dd:d9:dd:c25:c25c:400a:2a5
1672c19:dd:d9:dd:c25:c25c:400a:2a6/1282c19:dd:d9:dd:c25:c25c:400a:2a6
1682c19:dd:d9:dd:c25:c25c:400a:2a7/1282c19:dd:d9:dd:c25:c25c:400a:2a7
1692c19:dd:d9:dd:c25:c25c:400a:2a8/1282c19:dd:d9:dd:c25:c25c:400a:2a8
1702c19:dd:d9:dd:c25:c25c:400a:2a9/1282c19:dd:d9:dd:c25:c25c:400a:2a9
1712c19:dd:d9:dd:c25:c25c:400a:2aa/1282c19:dd:d9:dd:c25:c25c:400a:2aa
1722c19:dd:d9:dd:c25:c25c:400a:2ab/1282c19:dd:d9:dd:c25:c25c:400a:2ab
1732c19:dd:d9:dd:c25:c25c:400a:2ac/1282c19:dd:d9:dd:c25:c25c:400a:2ac
1742c19:dd:d9:dd:c25:c25c:400a:2ad/1282c19:dd:d9:dd:c25:c25c:400a:2ad
1752c19:dd:d9:dd:c25:c25c:400a:2ae/1282c19:dd:d9:dd:c25:c25c:400a:2ae
1762c19:dd:d9:dd:c25:c25c:400a:2af/1282c19:dd:d9:dd:c25:c25c:400a:2af
1772c19:dd:d9:dd:c25:c25c:400a:2b0/1282c19:dd:d9:dd:c25:c25c:400a:2b0
1782c19:dd:d9:dd:c25:c25c:400a:2b1/1282c19:dd:d9:dd:c25:c25c:400a:2b1
1792c19:dd:d9:dd:c25:c25c:400a:2b2/1282c19:dd:d9:dd:c25:c25c:400a:2b2
1802c19:dd:d9:dd:c25:c25c:400a:2b3/1282c19:dd:d9:dd:c25:c25c:400a:2b3
1812c19:dd:d9:dd:c25:c25c:400a:2b4/1282c19:dd:d9:dd:c25:c25c:400a:2b4
1822c19:dd:d9:dd:c25:c25c:400a:2b5/1282c19:dd:d9:dd:c25:c25c:400a:2b5
1832c19:dd:d9:dd:c25:c25c:400a:2b6/1282c19:dd:d9:dd:c25:c25c:400a:2b6
1842c19:dd:d9:dd:c25:c25c:400a:2b7/1282c19:dd:d9:dd:c25:c25c:400a:2b7
1852c19:dd:d9:dd:c25:c25c:400a:2b8/1282c19:dd:d9:dd:c25:c25c:400a:2b8
1862c19:dd:d9:dd:c25:c25c:400a:2b9/1282c19:dd:d9:dd:c25:c25c:400a:2b9
1872c19:dd:d9:dd:c25:c25c:400a:2ba/1282c19:dd:d9:dd:c25:c25c:400a:2ba
1882c19:dd:d9:dd:c25:c25c:400a:2bb/1282c19:dd:d9:dd:c25:c25c:400a:2bb
1892c19:dd:d9:dd:c25:c25c:400a:2bc/1282c19:dd:d9:dd:c25:c25c:400a:2bc
1902c19:dd:d9:dd:c25:c25c:400a:2bd/1282c19:dd:d9:dd:c25:c25c:400a:2bd
1912c19:dd:d9:dd:c25:c25c:400a:2be/1282c19:dd:d9:dd:c25:c25c:400a:2be
1922c19:dd:d9:dd:c25:c25c:400a:2bf/1282c19:dd:d9:dd:c25:c25c:400a:2bf
1932c19:dd:d9:dd:c25:c25c:400a:2c0/1282c19:dd:d9:dd:c25:c25c:400a:2c0
1942c19:dd:d9:dd:c25:c25c:400a:2c1/1282c19:dd:d9:dd:c25:c25c:400a:2c1
1952c19:dd:d9:dd:c25:c25c:400a:2c2/1282c19:dd:d9:dd:c25:c25c:400a:2c2
1962c19:dd:d9:dd:c25:c25c:400a:2c3/1282c19:dd:d9:dd:c25:c25c:400a:2c3
1972c19:dd:d9:dd:c25:c25c:400a:2c4/1282c19:dd:d9:dd:c25:c25c:400a:2c4
1982c19:dd:d9:dd:c25:c25c:400a:2c5/1282c19:dd:d9:dd:c25:c25c:400a:2c5
1992c19:dd:d9:dd:c25:c25c:400a:2c6/1282c19:dd:d9:dd:c25:c25c:400a:2c6
2002c19:dd:d9:dd:c25:c25c:400a:2c7/1282c19:dd:d9:dd:c25:c25c:400a:2c7
2012c19:dd:d9:dd:c25:c25c:400a:2c8/1282c19:dd:d9:dd:c25:c25c:400a:2c8
2022c19:dd:d9:dd:c25:c25c:400a:2c9/1282c19:dd:d9:dd:c25:c25c:400a:2c9
2032c19:dd:d9:dd:c25:c25c:400a:2ca/1282c19:dd:d9:dd:c25:c25c:400a:2ca
2042c19:dd:d9:dd:c25:c25c:400a:2cb/1282c19:dd:d9:dd:c25:c25c:400a:2cb
2052c19:dd:d9:dd:c25:c25c:400a:2cc/1282c19:dd:d9:dd:c25:c25c:400a:2cc
2062c19:dd:d9:dd:c25:c25c:400a:2cd/1282c19:dd:d9:dd:c25:c25c:400a:2cd
2072c19:dd:d9:dd:c25:c25c:400a:2ce/1282c19:dd:d9:dd:c25:c25c:400a:2ce
2082c19:dd:d9:dd:c25:c25c:400a:2cf/1282c19:dd:d9:dd:c25:c25c:400a:2cf
2092c19:dd:d9:dd:c25:c25c:400a:2d0/1282c19:dd:d9:dd:c25:c25c:400a:2d0
2102c19:dd:d9:dd:c25:c25c:400a:2d1/1282c19:dd:d9:dd:c25:c25c:400a:2d1
2112c19:dd:d9:dd:c25:c25c:400a:2d2/1282c19:dd:d9:dd:c25:c25c:400a:2d2
2122c19:dd:d9:dd:c25:c25c:400a:2d3/1282c19:dd:d9:dd:c25:c25c:400a:2d3
2132c19:dd:d9:dd:c25:c25c:400a:2d4/1282c19:dd:d9:dd:c25:c25c:400a:2d4
2142c19:dd:d9:dd:c25:c25c:400a:2d5/1282c19:dd:d9:dd:c25:c25c:400a:2d5
2152c19:dd:d9:dd:c25:c25c:400a:2d6/1282c19:dd:d9:dd:c25:c25c:400a:2d6
2162c19:dd:d9:dd:c25:c25c:400a:2d7/1282c19:dd:d9:dd:c25:c25c:400a:2d7
2172c19:dd:d9:dd:c25:c25c:400a:2d8/1282c19:dd:d9:dd:c25:c25c:400a:2d8
2182c19:dd:d9:dd:c25:c25c:400a:2d9/1282c19:dd:d9:dd:c25:c25c:400a:2d9
2192c19:dd:d9:dd:c25:c25c:400a:2da/1282c19:dd:d9:dd:c25:c25c:400a:2da
2202c19:dd:d9:dd:c25:c25c:400a:2db/1282c19:dd:d9:dd:c25:c25c:400a:2db
2212c19:dd:d9:dd:c25:c25c:400a:2dc/1282c19:dd:d9:dd:c25:c25c:400a:2dc
2222c19:dd:d9:dd:c25:c25c:400a:2dd/1282c19:dd:d9:dd:c25:c25c:400a:2dd
2232c19:dd:d9:dd:c25:c25c:400a:2de/1282c19:dd:d9:dd:c25:c25c:400a:2de
2242c19:dd:d9:dd:c25:c25c:400a:2df/1282c19:dd:d9:dd:c25:c25c:400a:2df
2252c19:dd:d9:dd:c25:c25c:400a:2e0/1282c19:dd:d9:dd:c25:c25c:400a:2e0
2262c19:dd:d9:dd:c25:c25c:400a:2e1/1282c19:dd:d9:dd:c25:c25c:400a:2e1
2272c19:dd:d9:dd:c25:c25c:400a:2e2/1282c19:dd:d9:dd:c25:c25c:400a:2e2
2282c19:dd:d9:dd:c25:c25c:400a:2e3/1282c19:dd:d9:dd:c25:c25c:400a:2e3
2292c19:dd:d9:dd:c25:c25c:400a:2e4/1282c19:dd:d9:dd:c25:c25c:400a:2e4
2302c19:dd:d9:dd:c25:c25c:400a:2e5/1282c19:dd:d9:dd:c25:c25c:400a:2e5
2312c19:dd:d9:dd:c25:c25c:400a:2e6/1282c19:dd:d9:dd:c25:c25c:400a:2e6
2322c19:dd:d9:dd:c25:c25c:400a:2e7/1282c19:dd:d9:dd:c25:c25c:400a:2e7
2332c19:dd:d9:dd:c25:c25c:400a:2e8/1282c19:dd:d9:dd:c25:c25c:400a:2e8
2342c19:dd:d9:dd:c25:c25c:400a:2e9/1282c19:dd:d9:dd:c25:c25c:400a:2e9
2352c19:dd:d9:dd:c25:c25c:400a:2ea/1282c19:dd:d9:dd:c25:c25c:400a:2ea
2362c19:dd:d9:dd:c25:c25c:400a:2eb/1282c19:dd:d9:dd:c25:c25c:400a:2eb
2372c19:dd:d9:dd:c25:c25c:400a:2ec/1282c19:dd:d9:dd:c25:c25c:400a:2ec
2382c19:dd:d9:dd:c25:c25c:400a:2ed/1282c19:dd:d9:dd:c25:c25c:400a:2ed
2392c19:dd:d9:dd:c25:c25c:400a:2ee/1282c19:dd:d9:dd:c25:c25c:400a:2ee
2402c19:dd:d9:dd:c25:c25c:400a:2ef/1282c19:dd:d9:dd:c25:c25c:400a:2ef
2412c19:dd:d9:dd:c25:c25c:400a:2f0/1282c19:dd:d9:dd:c25:c25c:400a:2f0
2422c19:dd:d9:dd:c25:c25c:400a:2f1/1282c19:dd:d9:dd:c25:c25c:400a:2f1
2432c19:dd:d9:dd:c25:c25c:400a:2f2/1282c19:dd:d9:dd:c25:c25c:400a:2f2
2442c19:dd:d9:dd:c25:c25c:400a:2f3/1282c19:dd:d9:dd:c25:c25c:400a:2f3
2452c19:dd:d9:dd:c25:c25c:400a:2f4/1282c19:dd:d9:dd:c25:c25c:400a:2f4
2462c19:dd:d9:dd:c25:c25c:400a:2f5/1282c19:dd:d9:dd:c25:c25c:400a:2f5
2472c19:dd:d9:dd:c25:c25c:400a:2f6/1282c19:dd:d9:dd:c25:c25c:400a:2f6
2482c19:dd:d9:dd:c25:c25c:400a:2f7/1282c19:dd:d9:dd:c25:c25c:400a:2f7
2492c19:dd:d9:dd:c25:c25c:400a:2f8/1282c19:dd:d9:dd:c25:c25c:400a:2f8
2502c19:dd:d9:dd:c25:c25c:400a:2f9/1282c19:dd:d9:dd:c25:c25c:400a:2f9
2512c19:dd:d9:dd:c25:c25c:400a:2fa/1282c19:dd:d9:dd:c25:c25c:400a:2fa
2522c19:dd:d9:dd:c25:c25c:400a:2fb/1282c19:dd:d9:dd:c25:c25c:400a:2fb
2532c19:dd:d9:dd:c25:c25c:400a:2fc/1282c19:dd:d9:dd:c25:c25c:400a:2fc
2542c19:dd:d9:dd:c25:c25c:400a:2fd/1282c19:dd:d9:dd:c25:c25c:400a:2fd
2552c19:dd:d9:dd:c25:c25c:400a:2fe/1282c19:dd:d9:dd:c25:c25c:400a:2fe
2562c19:dd:d9:dd:c25:c25c:400a:2ff/1282c19:dd:d9:dd:c25:c25c:400a:2ff

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.