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:c25:94de:1400/120
First address
2c19:dd:d9:dd:c25:c25:94de:1400
Last address
2c19:dd:d9:dd:c25:c25:94de:14ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:94de:1400
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
4.1.e.d.4.9.5.2.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:c25:94de:1400/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:94de:1400/1282c19:dd:d9:dd:c25:c25:94de:1400
22c19:dd:d9:dd:c25:c25:94de:1401/1282c19:dd:d9:dd:c25:c25:94de:1401
32c19:dd:d9:dd:c25:c25:94de:1402/1282c19:dd:d9:dd:c25:c25:94de:1402
42c19:dd:d9:dd:c25:c25:94de:1403/1282c19:dd:d9:dd:c25:c25:94de:1403
52c19:dd:d9:dd:c25:c25:94de:1404/1282c19:dd:d9:dd:c25:c25:94de:1404
62c19:dd:d9:dd:c25:c25:94de:1405/1282c19:dd:d9:dd:c25:c25:94de:1405
72c19:dd:d9:dd:c25:c25:94de:1406/1282c19:dd:d9:dd:c25:c25:94de:1406
82c19:dd:d9:dd:c25:c25:94de:1407/1282c19:dd:d9:dd:c25:c25:94de:1407
92c19:dd:d9:dd:c25:c25:94de:1408/1282c19:dd:d9:dd:c25:c25:94de:1408
102c19:dd:d9:dd:c25:c25:94de:1409/1282c19:dd:d9:dd:c25:c25:94de:1409
112c19:dd:d9:dd:c25:c25:94de:140a/1282c19:dd:d9:dd:c25:c25:94de:140a
122c19:dd:d9:dd:c25:c25:94de:140b/1282c19:dd:d9:dd:c25:c25:94de:140b
132c19:dd:d9:dd:c25:c25:94de:140c/1282c19:dd:d9:dd:c25:c25:94de:140c
142c19:dd:d9:dd:c25:c25:94de:140d/1282c19:dd:d9:dd:c25:c25:94de:140d
152c19:dd:d9:dd:c25:c25:94de:140e/1282c19:dd:d9:dd:c25:c25:94de:140e
162c19:dd:d9:dd:c25:c25:94de:140f/1282c19:dd:d9:dd:c25:c25:94de:140f
172c19:dd:d9:dd:c25:c25:94de:1410/1282c19:dd:d9:dd:c25:c25:94de:1410
182c19:dd:d9:dd:c25:c25:94de:1411/1282c19:dd:d9:dd:c25:c25:94de:1411
192c19:dd:d9:dd:c25:c25:94de:1412/1282c19:dd:d9:dd:c25:c25:94de:1412
202c19:dd:d9:dd:c25:c25:94de:1413/1282c19:dd:d9:dd:c25:c25:94de:1413
212c19:dd:d9:dd:c25:c25:94de:1414/1282c19:dd:d9:dd:c25:c25:94de:1414
222c19:dd:d9:dd:c25:c25:94de:1415/1282c19:dd:d9:dd:c25:c25:94de:1415
232c19:dd:d9:dd:c25:c25:94de:1416/1282c19:dd:d9:dd:c25:c25:94de:1416
242c19:dd:d9:dd:c25:c25:94de:1417/1282c19:dd:d9:dd:c25:c25:94de:1417
252c19:dd:d9:dd:c25:c25:94de:1418/1282c19:dd:d9:dd:c25:c25:94de:1418
262c19:dd:d9:dd:c25:c25:94de:1419/1282c19:dd:d9:dd:c25:c25:94de:1419
272c19:dd:d9:dd:c25:c25:94de:141a/1282c19:dd:d9:dd:c25:c25:94de:141a
282c19:dd:d9:dd:c25:c25:94de:141b/1282c19:dd:d9:dd:c25:c25:94de:141b
292c19:dd:d9:dd:c25:c25:94de:141c/1282c19:dd:d9:dd:c25:c25:94de:141c
302c19:dd:d9:dd:c25:c25:94de:141d/1282c19:dd:d9:dd:c25:c25:94de:141d
312c19:dd:d9:dd:c25:c25:94de:141e/1282c19:dd:d9:dd:c25:c25:94de:141e
322c19:dd:d9:dd:c25:c25:94de:141f/1282c19:dd:d9:dd:c25:c25:94de:141f
332c19:dd:d9:dd:c25:c25:94de:1420/1282c19:dd:d9:dd:c25:c25:94de:1420
342c19:dd:d9:dd:c25:c25:94de:1421/1282c19:dd:d9:dd:c25:c25:94de:1421
352c19:dd:d9:dd:c25:c25:94de:1422/1282c19:dd:d9:dd:c25:c25:94de:1422
362c19:dd:d9:dd:c25:c25:94de:1423/1282c19:dd:d9:dd:c25:c25:94de:1423
372c19:dd:d9:dd:c25:c25:94de:1424/1282c19:dd:d9:dd:c25:c25:94de:1424
382c19:dd:d9:dd:c25:c25:94de:1425/1282c19:dd:d9:dd:c25:c25:94de:1425
392c19:dd:d9:dd:c25:c25:94de:1426/1282c19:dd:d9:dd:c25:c25:94de:1426
402c19:dd:d9:dd:c25:c25:94de:1427/1282c19:dd:d9:dd:c25:c25:94de:1427
412c19:dd:d9:dd:c25:c25:94de:1428/1282c19:dd:d9:dd:c25:c25:94de:1428
422c19:dd:d9:dd:c25:c25:94de:1429/1282c19:dd:d9:dd:c25:c25:94de:1429
432c19:dd:d9:dd:c25:c25:94de:142a/1282c19:dd:d9:dd:c25:c25:94de:142a
442c19:dd:d9:dd:c25:c25:94de:142b/1282c19:dd:d9:dd:c25:c25:94de:142b
452c19:dd:d9:dd:c25:c25:94de:142c/1282c19:dd:d9:dd:c25:c25:94de:142c
462c19:dd:d9:dd:c25:c25:94de:142d/1282c19:dd:d9:dd:c25:c25:94de:142d
472c19:dd:d9:dd:c25:c25:94de:142e/1282c19:dd:d9:dd:c25:c25:94de:142e
482c19:dd:d9:dd:c25:c25:94de:142f/1282c19:dd:d9:dd:c25:c25:94de:142f
492c19:dd:d9:dd:c25:c25:94de:1430/1282c19:dd:d9:dd:c25:c25:94de:1430
502c19:dd:d9:dd:c25:c25:94de:1431/1282c19:dd:d9:dd:c25:c25:94de:1431
512c19:dd:d9:dd:c25:c25:94de:1432/1282c19:dd:d9:dd:c25:c25:94de:1432
522c19:dd:d9:dd:c25:c25:94de:1433/1282c19:dd:d9:dd:c25:c25:94de:1433
532c19:dd:d9:dd:c25:c25:94de:1434/1282c19:dd:d9:dd:c25:c25:94de:1434
542c19:dd:d9:dd:c25:c25:94de:1435/1282c19:dd:d9:dd:c25:c25:94de:1435
552c19:dd:d9:dd:c25:c25:94de:1436/1282c19:dd:d9:dd:c25:c25:94de:1436
562c19:dd:d9:dd:c25:c25:94de:1437/1282c19:dd:d9:dd:c25:c25:94de:1437
572c19:dd:d9:dd:c25:c25:94de:1438/1282c19:dd:d9:dd:c25:c25:94de:1438
582c19:dd:d9:dd:c25:c25:94de:1439/1282c19:dd:d9:dd:c25:c25:94de:1439
592c19:dd:d9:dd:c25:c25:94de:143a/1282c19:dd:d9:dd:c25:c25:94de:143a
602c19:dd:d9:dd:c25:c25:94de:143b/1282c19:dd:d9:dd:c25:c25:94de:143b
612c19:dd:d9:dd:c25:c25:94de:143c/1282c19:dd:d9:dd:c25:c25:94de:143c
622c19:dd:d9:dd:c25:c25:94de:143d/1282c19:dd:d9:dd:c25:c25:94de:143d
632c19:dd:d9:dd:c25:c25:94de:143e/1282c19:dd:d9:dd:c25:c25:94de:143e
642c19:dd:d9:dd:c25:c25:94de:143f/1282c19:dd:d9:dd:c25:c25:94de:143f
652c19:dd:d9:dd:c25:c25:94de:1440/1282c19:dd:d9:dd:c25:c25:94de:1440
662c19:dd:d9:dd:c25:c25:94de:1441/1282c19:dd:d9:dd:c25:c25:94de:1441
672c19:dd:d9:dd:c25:c25:94de:1442/1282c19:dd:d9:dd:c25:c25:94de:1442
682c19:dd:d9:dd:c25:c25:94de:1443/1282c19:dd:d9:dd:c25:c25:94de:1443
692c19:dd:d9:dd:c25:c25:94de:1444/1282c19:dd:d9:dd:c25:c25:94de:1444
702c19:dd:d9:dd:c25:c25:94de:1445/1282c19:dd:d9:dd:c25:c25:94de:1445
712c19:dd:d9:dd:c25:c25:94de:1446/1282c19:dd:d9:dd:c25:c25:94de:1446
722c19:dd:d9:dd:c25:c25:94de:1447/1282c19:dd:d9:dd:c25:c25:94de:1447
732c19:dd:d9:dd:c25:c25:94de:1448/1282c19:dd:d9:dd:c25:c25:94de:1448
742c19:dd:d9:dd:c25:c25:94de:1449/1282c19:dd:d9:dd:c25:c25:94de:1449
752c19:dd:d9:dd:c25:c25:94de:144a/1282c19:dd:d9:dd:c25:c25:94de:144a
762c19:dd:d9:dd:c25:c25:94de:144b/1282c19:dd:d9:dd:c25:c25:94de:144b
772c19:dd:d9:dd:c25:c25:94de:144c/1282c19:dd:d9:dd:c25:c25:94de:144c
782c19:dd:d9:dd:c25:c25:94de:144d/1282c19:dd:d9:dd:c25:c25:94de:144d
792c19:dd:d9:dd:c25:c25:94de:144e/1282c19:dd:d9:dd:c25:c25:94de:144e
802c19:dd:d9:dd:c25:c25:94de:144f/1282c19:dd:d9:dd:c25:c25:94de:144f
812c19:dd:d9:dd:c25:c25:94de:1450/1282c19:dd:d9:dd:c25:c25:94de:1450
822c19:dd:d9:dd:c25:c25:94de:1451/1282c19:dd:d9:dd:c25:c25:94de:1451
832c19:dd:d9:dd:c25:c25:94de:1452/1282c19:dd:d9:dd:c25:c25:94de:1452
842c19:dd:d9:dd:c25:c25:94de:1453/1282c19:dd:d9:dd:c25:c25:94de:1453
852c19:dd:d9:dd:c25:c25:94de:1454/1282c19:dd:d9:dd:c25:c25:94de:1454
862c19:dd:d9:dd:c25:c25:94de:1455/1282c19:dd:d9:dd:c25:c25:94de:1455
872c19:dd:d9:dd:c25:c25:94de:1456/1282c19:dd:d9:dd:c25:c25:94de:1456
882c19:dd:d9:dd:c25:c25:94de:1457/1282c19:dd:d9:dd:c25:c25:94de:1457
892c19:dd:d9:dd:c25:c25:94de:1458/1282c19:dd:d9:dd:c25:c25:94de:1458
902c19:dd:d9:dd:c25:c25:94de:1459/1282c19:dd:d9:dd:c25:c25:94de:1459
912c19:dd:d9:dd:c25:c25:94de:145a/1282c19:dd:d9:dd:c25:c25:94de:145a
922c19:dd:d9:dd:c25:c25:94de:145b/1282c19:dd:d9:dd:c25:c25:94de:145b
932c19:dd:d9:dd:c25:c25:94de:145c/1282c19:dd:d9:dd:c25:c25:94de:145c
942c19:dd:d9:dd:c25:c25:94de:145d/1282c19:dd:d9:dd:c25:c25:94de:145d
952c19:dd:d9:dd:c25:c25:94de:145e/1282c19:dd:d9:dd:c25:c25:94de:145e
962c19:dd:d9:dd:c25:c25:94de:145f/1282c19:dd:d9:dd:c25:c25:94de:145f
972c19:dd:d9:dd:c25:c25:94de:1460/1282c19:dd:d9:dd:c25:c25:94de:1460
982c19:dd:d9:dd:c25:c25:94de:1461/1282c19:dd:d9:dd:c25:c25:94de:1461
992c19:dd:d9:dd:c25:c25:94de:1462/1282c19:dd:d9:dd:c25:c25:94de:1462
1002c19:dd:d9:dd:c25:c25:94de:1463/1282c19:dd:d9:dd:c25:c25:94de:1463
1012c19:dd:d9:dd:c25:c25:94de:1464/1282c19:dd:d9:dd:c25:c25:94de:1464
1022c19:dd:d9:dd:c25:c25:94de:1465/1282c19:dd:d9:dd:c25:c25:94de:1465
1032c19:dd:d9:dd:c25:c25:94de:1466/1282c19:dd:d9:dd:c25:c25:94de:1466
1042c19:dd:d9:dd:c25:c25:94de:1467/1282c19:dd:d9:dd:c25:c25:94de:1467
1052c19:dd:d9:dd:c25:c25:94de:1468/1282c19:dd:d9:dd:c25:c25:94de:1468
1062c19:dd:d9:dd:c25:c25:94de:1469/1282c19:dd:d9:dd:c25:c25:94de:1469
1072c19:dd:d9:dd:c25:c25:94de:146a/1282c19:dd:d9:dd:c25:c25:94de:146a
1082c19:dd:d9:dd:c25:c25:94de:146b/1282c19:dd:d9:dd:c25:c25:94de:146b
1092c19:dd:d9:dd:c25:c25:94de:146c/1282c19:dd:d9:dd:c25:c25:94de:146c
1102c19:dd:d9:dd:c25:c25:94de:146d/1282c19:dd:d9:dd:c25:c25:94de:146d
1112c19:dd:d9:dd:c25:c25:94de:146e/1282c19:dd:d9:dd:c25:c25:94de:146e
1122c19:dd:d9:dd:c25:c25:94de:146f/1282c19:dd:d9:dd:c25:c25:94de:146f
1132c19:dd:d9:dd:c25:c25:94de:1470/1282c19:dd:d9:dd:c25:c25:94de:1470
1142c19:dd:d9:dd:c25:c25:94de:1471/1282c19:dd:d9:dd:c25:c25:94de:1471
1152c19:dd:d9:dd:c25:c25:94de:1472/1282c19:dd:d9:dd:c25:c25:94de:1472
1162c19:dd:d9:dd:c25:c25:94de:1473/1282c19:dd:d9:dd:c25:c25:94de:1473
1172c19:dd:d9:dd:c25:c25:94de:1474/1282c19:dd:d9:dd:c25:c25:94de:1474
1182c19:dd:d9:dd:c25:c25:94de:1475/1282c19:dd:d9:dd:c25:c25:94de:1475
1192c19:dd:d9:dd:c25:c25:94de:1476/1282c19:dd:d9:dd:c25:c25:94de:1476
1202c19:dd:d9:dd:c25:c25:94de:1477/1282c19:dd:d9:dd:c25:c25:94de:1477
1212c19:dd:d9:dd:c25:c25:94de:1478/1282c19:dd:d9:dd:c25:c25:94de:1478
1222c19:dd:d9:dd:c25:c25:94de:1479/1282c19:dd:d9:dd:c25:c25:94de:1479
1232c19:dd:d9:dd:c25:c25:94de:147a/1282c19:dd:d9:dd:c25:c25:94de:147a
1242c19:dd:d9:dd:c25:c25:94de:147b/1282c19:dd:d9:dd:c25:c25:94de:147b
1252c19:dd:d9:dd:c25:c25:94de:147c/1282c19:dd:d9:dd:c25:c25:94de:147c
1262c19:dd:d9:dd:c25:c25:94de:147d/1282c19:dd:d9:dd:c25:c25:94de:147d
1272c19:dd:d9:dd:c25:c25:94de:147e/1282c19:dd:d9:dd:c25:c25:94de:147e
1282c19:dd:d9:dd:c25:c25:94de:147f/1282c19:dd:d9:dd:c25:c25:94de:147f
1292c19:dd:d9:dd:c25:c25:94de:1480/1282c19:dd:d9:dd:c25:c25:94de:1480
1302c19:dd:d9:dd:c25:c25:94de:1481/1282c19:dd:d9:dd:c25:c25:94de:1481
1312c19:dd:d9:dd:c25:c25:94de:1482/1282c19:dd:d9:dd:c25:c25:94de:1482
1322c19:dd:d9:dd:c25:c25:94de:1483/1282c19:dd:d9:dd:c25:c25:94de:1483
1332c19:dd:d9:dd:c25:c25:94de:1484/1282c19:dd:d9:dd:c25:c25:94de:1484
1342c19:dd:d9:dd:c25:c25:94de:1485/1282c19:dd:d9:dd:c25:c25:94de:1485
1352c19:dd:d9:dd:c25:c25:94de:1486/1282c19:dd:d9:dd:c25:c25:94de:1486
1362c19:dd:d9:dd:c25:c25:94de:1487/1282c19:dd:d9:dd:c25:c25:94de:1487
1372c19:dd:d9:dd:c25:c25:94de:1488/1282c19:dd:d9:dd:c25:c25:94de:1488
1382c19:dd:d9:dd:c25:c25:94de:1489/1282c19:dd:d9:dd:c25:c25:94de:1489
1392c19:dd:d9:dd:c25:c25:94de:148a/1282c19:dd:d9:dd:c25:c25:94de:148a
1402c19:dd:d9:dd:c25:c25:94de:148b/1282c19:dd:d9:dd:c25:c25:94de:148b
1412c19:dd:d9:dd:c25:c25:94de:148c/1282c19:dd:d9:dd:c25:c25:94de:148c
1422c19:dd:d9:dd:c25:c25:94de:148d/1282c19:dd:d9:dd:c25:c25:94de:148d
1432c19:dd:d9:dd:c25:c25:94de:148e/1282c19:dd:d9:dd:c25:c25:94de:148e
1442c19:dd:d9:dd:c25:c25:94de:148f/1282c19:dd:d9:dd:c25:c25:94de:148f
1452c19:dd:d9:dd:c25:c25:94de:1490/1282c19:dd:d9:dd:c25:c25:94de:1490
1462c19:dd:d9:dd:c25:c25:94de:1491/1282c19:dd:d9:dd:c25:c25:94de:1491
1472c19:dd:d9:dd:c25:c25:94de:1492/1282c19:dd:d9:dd:c25:c25:94de:1492
1482c19:dd:d9:dd:c25:c25:94de:1493/1282c19:dd:d9:dd:c25:c25:94de:1493
1492c19:dd:d9:dd:c25:c25:94de:1494/1282c19:dd:d9:dd:c25:c25:94de:1494
1502c19:dd:d9:dd:c25:c25:94de:1495/1282c19:dd:d9:dd:c25:c25:94de:1495
1512c19:dd:d9:dd:c25:c25:94de:1496/1282c19:dd:d9:dd:c25:c25:94de:1496
1522c19:dd:d9:dd:c25:c25:94de:1497/1282c19:dd:d9:dd:c25:c25:94de:1497
1532c19:dd:d9:dd:c25:c25:94de:1498/1282c19:dd:d9:dd:c25:c25:94de:1498
1542c19:dd:d9:dd:c25:c25:94de:1499/1282c19:dd:d9:dd:c25:c25:94de:1499
1552c19:dd:d9:dd:c25:c25:94de:149a/1282c19:dd:d9:dd:c25:c25:94de:149a
1562c19:dd:d9:dd:c25:c25:94de:149b/1282c19:dd:d9:dd:c25:c25:94de:149b
1572c19:dd:d9:dd:c25:c25:94de:149c/1282c19:dd:d9:dd:c25:c25:94de:149c
1582c19:dd:d9:dd:c25:c25:94de:149d/1282c19:dd:d9:dd:c25:c25:94de:149d
1592c19:dd:d9:dd:c25:c25:94de:149e/1282c19:dd:d9:dd:c25:c25:94de:149e
1602c19:dd:d9:dd:c25:c25:94de:149f/1282c19:dd:d9:dd:c25:c25:94de:149f
1612c19:dd:d9:dd:c25:c25:94de:14a0/1282c19:dd:d9:dd:c25:c25:94de:14a0
1622c19:dd:d9:dd:c25:c25:94de:14a1/1282c19:dd:d9:dd:c25:c25:94de:14a1
1632c19:dd:d9:dd:c25:c25:94de:14a2/1282c19:dd:d9:dd:c25:c25:94de:14a2
1642c19:dd:d9:dd:c25:c25:94de:14a3/1282c19:dd:d9:dd:c25:c25:94de:14a3
1652c19:dd:d9:dd:c25:c25:94de:14a4/1282c19:dd:d9:dd:c25:c25:94de:14a4
1662c19:dd:d9:dd:c25:c25:94de:14a5/1282c19:dd:d9:dd:c25:c25:94de:14a5
1672c19:dd:d9:dd:c25:c25:94de:14a6/1282c19:dd:d9:dd:c25:c25:94de:14a6
1682c19:dd:d9:dd:c25:c25:94de:14a7/1282c19:dd:d9:dd:c25:c25:94de:14a7
1692c19:dd:d9:dd:c25:c25:94de:14a8/1282c19:dd:d9:dd:c25:c25:94de:14a8
1702c19:dd:d9:dd:c25:c25:94de:14a9/1282c19:dd:d9:dd:c25:c25:94de:14a9
1712c19:dd:d9:dd:c25:c25:94de:14aa/1282c19:dd:d9:dd:c25:c25:94de:14aa
1722c19:dd:d9:dd:c25:c25:94de:14ab/1282c19:dd:d9:dd:c25:c25:94de:14ab
1732c19:dd:d9:dd:c25:c25:94de:14ac/1282c19:dd:d9:dd:c25:c25:94de:14ac
1742c19:dd:d9:dd:c25:c25:94de:14ad/1282c19:dd:d9:dd:c25:c25:94de:14ad
1752c19:dd:d9:dd:c25:c25:94de:14ae/1282c19:dd:d9:dd:c25:c25:94de:14ae
1762c19:dd:d9:dd:c25:c25:94de:14af/1282c19:dd:d9:dd:c25:c25:94de:14af
1772c19:dd:d9:dd:c25:c25:94de:14b0/1282c19:dd:d9:dd:c25:c25:94de:14b0
1782c19:dd:d9:dd:c25:c25:94de:14b1/1282c19:dd:d9:dd:c25:c25:94de:14b1
1792c19:dd:d9:dd:c25:c25:94de:14b2/1282c19:dd:d9:dd:c25:c25:94de:14b2
1802c19:dd:d9:dd:c25:c25:94de:14b3/1282c19:dd:d9:dd:c25:c25:94de:14b3
1812c19:dd:d9:dd:c25:c25:94de:14b4/1282c19:dd:d9:dd:c25:c25:94de:14b4
1822c19:dd:d9:dd:c25:c25:94de:14b5/1282c19:dd:d9:dd:c25:c25:94de:14b5
1832c19:dd:d9:dd:c25:c25:94de:14b6/1282c19:dd:d9:dd:c25:c25:94de:14b6
1842c19:dd:d9:dd:c25:c25:94de:14b7/1282c19:dd:d9:dd:c25:c25:94de:14b7
1852c19:dd:d9:dd:c25:c25:94de:14b8/1282c19:dd:d9:dd:c25:c25:94de:14b8
1862c19:dd:d9:dd:c25:c25:94de:14b9/1282c19:dd:d9:dd:c25:c25:94de:14b9
1872c19:dd:d9:dd:c25:c25:94de:14ba/1282c19:dd:d9:dd:c25:c25:94de:14ba
1882c19:dd:d9:dd:c25:c25:94de:14bb/1282c19:dd:d9:dd:c25:c25:94de:14bb
1892c19:dd:d9:dd:c25:c25:94de:14bc/1282c19:dd:d9:dd:c25:c25:94de:14bc
1902c19:dd:d9:dd:c25:c25:94de:14bd/1282c19:dd:d9:dd:c25:c25:94de:14bd
1912c19:dd:d9:dd:c25:c25:94de:14be/1282c19:dd:d9:dd:c25:c25:94de:14be
1922c19:dd:d9:dd:c25:c25:94de:14bf/1282c19:dd:d9:dd:c25:c25:94de:14bf
1932c19:dd:d9:dd:c25:c25:94de:14c0/1282c19:dd:d9:dd:c25:c25:94de:14c0
1942c19:dd:d9:dd:c25:c25:94de:14c1/1282c19:dd:d9:dd:c25:c25:94de:14c1
1952c19:dd:d9:dd:c25:c25:94de:14c2/1282c19:dd:d9:dd:c25:c25:94de:14c2
1962c19:dd:d9:dd:c25:c25:94de:14c3/1282c19:dd:d9:dd:c25:c25:94de:14c3
1972c19:dd:d9:dd:c25:c25:94de:14c4/1282c19:dd:d9:dd:c25:c25:94de:14c4
1982c19:dd:d9:dd:c25:c25:94de:14c5/1282c19:dd:d9:dd:c25:c25:94de:14c5
1992c19:dd:d9:dd:c25:c25:94de:14c6/1282c19:dd:d9:dd:c25:c25:94de:14c6
2002c19:dd:d9:dd:c25:c25:94de:14c7/1282c19:dd:d9:dd:c25:c25:94de:14c7
2012c19:dd:d9:dd:c25:c25:94de:14c8/1282c19:dd:d9:dd:c25:c25:94de:14c8
2022c19:dd:d9:dd:c25:c25:94de:14c9/1282c19:dd:d9:dd:c25:c25:94de:14c9
2032c19:dd:d9:dd:c25:c25:94de:14ca/1282c19:dd:d9:dd:c25:c25:94de:14ca
2042c19:dd:d9:dd:c25:c25:94de:14cb/1282c19:dd:d9:dd:c25:c25:94de:14cb
2052c19:dd:d9:dd:c25:c25:94de:14cc/1282c19:dd:d9:dd:c25:c25:94de:14cc
2062c19:dd:d9:dd:c25:c25:94de:14cd/1282c19:dd:d9:dd:c25:c25:94de:14cd
2072c19:dd:d9:dd:c25:c25:94de:14ce/1282c19:dd:d9:dd:c25:c25:94de:14ce
2082c19:dd:d9:dd:c25:c25:94de:14cf/1282c19:dd:d9:dd:c25:c25:94de:14cf
2092c19:dd:d9:dd:c25:c25:94de:14d0/1282c19:dd:d9:dd:c25:c25:94de:14d0
2102c19:dd:d9:dd:c25:c25:94de:14d1/1282c19:dd:d9:dd:c25:c25:94de:14d1
2112c19:dd:d9:dd:c25:c25:94de:14d2/1282c19:dd:d9:dd:c25:c25:94de:14d2
2122c19:dd:d9:dd:c25:c25:94de:14d3/1282c19:dd:d9:dd:c25:c25:94de:14d3
2132c19:dd:d9:dd:c25:c25:94de:14d4/1282c19:dd:d9:dd:c25:c25:94de:14d4
2142c19:dd:d9:dd:c25:c25:94de:14d5/1282c19:dd:d9:dd:c25:c25:94de:14d5
2152c19:dd:d9:dd:c25:c25:94de:14d6/1282c19:dd:d9:dd:c25:c25:94de:14d6
2162c19:dd:d9:dd:c25:c25:94de:14d7/1282c19:dd:d9:dd:c25:c25:94de:14d7
2172c19:dd:d9:dd:c25:c25:94de:14d8/1282c19:dd:d9:dd:c25:c25:94de:14d8
2182c19:dd:d9:dd:c25:c25:94de:14d9/1282c19:dd:d9:dd:c25:c25:94de:14d9
2192c19:dd:d9:dd:c25:c25:94de:14da/1282c19:dd:d9:dd:c25:c25:94de:14da
2202c19:dd:d9:dd:c25:c25:94de:14db/1282c19:dd:d9:dd:c25:c25:94de:14db
2212c19:dd:d9:dd:c25:c25:94de:14dc/1282c19:dd:d9:dd:c25:c25:94de:14dc
2222c19:dd:d9:dd:c25:c25:94de:14dd/1282c19:dd:d9:dd:c25:c25:94de:14dd
2232c19:dd:d9:dd:c25:c25:94de:14de/1282c19:dd:d9:dd:c25:c25:94de:14de
2242c19:dd:d9:dd:c25:c25:94de:14df/1282c19:dd:d9:dd:c25:c25:94de:14df
2252c19:dd:d9:dd:c25:c25:94de:14e0/1282c19:dd:d9:dd:c25:c25:94de:14e0
2262c19:dd:d9:dd:c25:c25:94de:14e1/1282c19:dd:d9:dd:c25:c25:94de:14e1
2272c19:dd:d9:dd:c25:c25:94de:14e2/1282c19:dd:d9:dd:c25:c25:94de:14e2
2282c19:dd:d9:dd:c25:c25:94de:14e3/1282c19:dd:d9:dd:c25:c25:94de:14e3
2292c19:dd:d9:dd:c25:c25:94de:14e4/1282c19:dd:d9:dd:c25:c25:94de:14e4
2302c19:dd:d9:dd:c25:c25:94de:14e5/1282c19:dd:d9:dd:c25:c25:94de:14e5
2312c19:dd:d9:dd:c25:c25:94de:14e6/1282c19:dd:d9:dd:c25:c25:94de:14e6
2322c19:dd:d9:dd:c25:c25:94de:14e7/1282c19:dd:d9:dd:c25:c25:94de:14e7
2332c19:dd:d9:dd:c25:c25:94de:14e8/1282c19:dd:d9:dd:c25:c25:94de:14e8
2342c19:dd:d9:dd:c25:c25:94de:14e9/1282c19:dd:d9:dd:c25:c25:94de:14e9
2352c19:dd:d9:dd:c25:c25:94de:14ea/1282c19:dd:d9:dd:c25:c25:94de:14ea
2362c19:dd:d9:dd:c25:c25:94de:14eb/1282c19:dd:d9:dd:c25:c25:94de:14eb
2372c19:dd:d9:dd:c25:c25:94de:14ec/1282c19:dd:d9:dd:c25:c25:94de:14ec
2382c19:dd:d9:dd:c25:c25:94de:14ed/1282c19:dd:d9:dd:c25:c25:94de:14ed
2392c19:dd:d9:dd:c25:c25:94de:14ee/1282c19:dd:d9:dd:c25:c25:94de:14ee
2402c19:dd:d9:dd:c25:c25:94de:14ef/1282c19:dd:d9:dd:c25:c25:94de:14ef
2412c19:dd:d9:dd:c25:c25:94de:14f0/1282c19:dd:d9:dd:c25:c25:94de:14f0
2422c19:dd:d9:dd:c25:c25:94de:14f1/1282c19:dd:d9:dd:c25:c25:94de:14f1
2432c19:dd:d9:dd:c25:c25:94de:14f2/1282c19:dd:d9:dd:c25:c25:94de:14f2
2442c19:dd:d9:dd:c25:c25:94de:14f3/1282c19:dd:d9:dd:c25:c25:94de:14f3
2452c19:dd:d9:dd:c25:c25:94de:14f4/1282c19:dd:d9:dd:c25:c25:94de:14f4
2462c19:dd:d9:dd:c25:c25:94de:14f5/1282c19:dd:d9:dd:c25:c25:94de:14f5
2472c19:dd:d9:dd:c25:c25:94de:14f6/1282c19:dd:d9:dd:c25:c25:94de:14f6
2482c19:dd:d9:dd:c25:c25:94de:14f7/1282c19:dd:d9:dd:c25:c25:94de:14f7
2492c19:dd:d9:dd:c25:c25:94de:14f8/1282c19:dd:d9:dd:c25:c25:94de:14f8
2502c19:dd:d9:dd:c25:c25:94de:14f9/1282c19:dd:d9:dd:c25:c25:94de:14f9
2512c19:dd:d9:dd:c25:c25:94de:14fa/1282c19:dd:d9:dd:c25:c25:94de:14fa
2522c19:dd:d9:dd:c25:c25:94de:14fb/1282c19:dd:d9:dd:c25:c25:94de:14fb
2532c19:dd:d9:dd:c25:c25:94de:14fc/1282c19:dd:d9:dd:c25:c25:94de:14fc
2542c19:dd:d9:dd:c25:c25:94de:14fd/1282c19:dd:d9:dd:c25:c25:94de:14fd
2552c19:dd:d9:dd:c25:c25:94de:14fe/1282c19:dd:d9:dd:c25:c25:94de:14fe
2562c19:dd:d9:dd:c25:c25:94de:14ff/1282c19:dd:d9:dd:c25:c25:94de:14ff

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.