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:c25f:dd4e:dd:dd:1500/120
First address
2c19:dd:c25:c25f:dd4e:dd:dd:1500
Last address
2c19:dd:c25:c25f:dd4e:dd:dd:15ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:0c25:c25f:dd4e:00dd:00dd:1500
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
5.1.d.d.0.0.d.d.0.0.e.4.d.d.f.5.2.c.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:c25f:dd4e:dd:dd:1500/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:c25:c25f:dd4e:dd:dd:1500/1282c19:dd:c25:c25f:dd4e:dd:dd:1500
22c19:dd:c25:c25f:dd4e:dd:dd:1501/1282c19:dd:c25:c25f:dd4e:dd:dd:1501
32c19:dd:c25:c25f:dd4e:dd:dd:1502/1282c19:dd:c25:c25f:dd4e:dd:dd:1502
42c19:dd:c25:c25f:dd4e:dd:dd:1503/1282c19:dd:c25:c25f:dd4e:dd:dd:1503
52c19:dd:c25:c25f:dd4e:dd:dd:1504/1282c19:dd:c25:c25f:dd4e:dd:dd:1504
62c19:dd:c25:c25f:dd4e:dd:dd:1505/1282c19:dd:c25:c25f:dd4e:dd:dd:1505
72c19:dd:c25:c25f:dd4e:dd:dd:1506/1282c19:dd:c25:c25f:dd4e:dd:dd:1506
82c19:dd:c25:c25f:dd4e:dd:dd:1507/1282c19:dd:c25:c25f:dd4e:dd:dd:1507
92c19:dd:c25:c25f:dd4e:dd:dd:1508/1282c19:dd:c25:c25f:dd4e:dd:dd:1508
102c19:dd:c25:c25f:dd4e:dd:dd:1509/1282c19:dd:c25:c25f:dd4e:dd:dd:1509
112c19:dd:c25:c25f:dd4e:dd:dd:150a/1282c19:dd:c25:c25f:dd4e:dd:dd:150a
122c19:dd:c25:c25f:dd4e:dd:dd:150b/1282c19:dd:c25:c25f:dd4e:dd:dd:150b
132c19:dd:c25:c25f:dd4e:dd:dd:150c/1282c19:dd:c25:c25f:dd4e:dd:dd:150c
142c19:dd:c25:c25f:dd4e:dd:dd:150d/1282c19:dd:c25:c25f:dd4e:dd:dd:150d
152c19:dd:c25:c25f:dd4e:dd:dd:150e/1282c19:dd:c25:c25f:dd4e:dd:dd:150e
162c19:dd:c25:c25f:dd4e:dd:dd:150f/1282c19:dd:c25:c25f:dd4e:dd:dd:150f
172c19:dd:c25:c25f:dd4e:dd:dd:1510/1282c19:dd:c25:c25f:dd4e:dd:dd:1510
182c19:dd:c25:c25f:dd4e:dd:dd:1511/1282c19:dd:c25:c25f:dd4e:dd:dd:1511
192c19:dd:c25:c25f:dd4e:dd:dd:1512/1282c19:dd:c25:c25f:dd4e:dd:dd:1512
202c19:dd:c25:c25f:dd4e:dd:dd:1513/1282c19:dd:c25:c25f:dd4e:dd:dd:1513
212c19:dd:c25:c25f:dd4e:dd:dd:1514/1282c19:dd:c25:c25f:dd4e:dd:dd:1514
222c19:dd:c25:c25f:dd4e:dd:dd:1515/1282c19:dd:c25:c25f:dd4e:dd:dd:1515
232c19:dd:c25:c25f:dd4e:dd:dd:1516/1282c19:dd:c25:c25f:dd4e:dd:dd:1516
242c19:dd:c25:c25f:dd4e:dd:dd:1517/1282c19:dd:c25:c25f:dd4e:dd:dd:1517
252c19:dd:c25:c25f:dd4e:dd:dd:1518/1282c19:dd:c25:c25f:dd4e:dd:dd:1518
262c19:dd:c25:c25f:dd4e:dd:dd:1519/1282c19:dd:c25:c25f:dd4e:dd:dd:1519
272c19:dd:c25:c25f:dd4e:dd:dd:151a/1282c19:dd:c25:c25f:dd4e:dd:dd:151a
282c19:dd:c25:c25f:dd4e:dd:dd:151b/1282c19:dd:c25:c25f:dd4e:dd:dd:151b
292c19:dd:c25:c25f:dd4e:dd:dd:151c/1282c19:dd:c25:c25f:dd4e:dd:dd:151c
302c19:dd:c25:c25f:dd4e:dd:dd:151d/1282c19:dd:c25:c25f:dd4e:dd:dd:151d
312c19:dd:c25:c25f:dd4e:dd:dd:151e/1282c19:dd:c25:c25f:dd4e:dd:dd:151e
322c19:dd:c25:c25f:dd4e:dd:dd:151f/1282c19:dd:c25:c25f:dd4e:dd:dd:151f
332c19:dd:c25:c25f:dd4e:dd:dd:1520/1282c19:dd:c25:c25f:dd4e:dd:dd:1520
342c19:dd:c25:c25f:dd4e:dd:dd:1521/1282c19:dd:c25:c25f:dd4e:dd:dd:1521
352c19:dd:c25:c25f:dd4e:dd:dd:1522/1282c19:dd:c25:c25f:dd4e:dd:dd:1522
362c19:dd:c25:c25f:dd4e:dd:dd:1523/1282c19:dd:c25:c25f:dd4e:dd:dd:1523
372c19:dd:c25:c25f:dd4e:dd:dd:1524/1282c19:dd:c25:c25f:dd4e:dd:dd:1524
382c19:dd:c25:c25f:dd4e:dd:dd:1525/1282c19:dd:c25:c25f:dd4e:dd:dd:1525
392c19:dd:c25:c25f:dd4e:dd:dd:1526/1282c19:dd:c25:c25f:dd4e:dd:dd:1526
402c19:dd:c25:c25f:dd4e:dd:dd:1527/1282c19:dd:c25:c25f:dd4e:dd:dd:1527
412c19:dd:c25:c25f:dd4e:dd:dd:1528/1282c19:dd:c25:c25f:dd4e:dd:dd:1528
422c19:dd:c25:c25f:dd4e:dd:dd:1529/1282c19:dd:c25:c25f:dd4e:dd:dd:1529
432c19:dd:c25:c25f:dd4e:dd:dd:152a/1282c19:dd:c25:c25f:dd4e:dd:dd:152a
442c19:dd:c25:c25f:dd4e:dd:dd:152b/1282c19:dd:c25:c25f:dd4e:dd:dd:152b
452c19:dd:c25:c25f:dd4e:dd:dd:152c/1282c19:dd:c25:c25f:dd4e:dd:dd:152c
462c19:dd:c25:c25f:dd4e:dd:dd:152d/1282c19:dd:c25:c25f:dd4e:dd:dd:152d
472c19:dd:c25:c25f:dd4e:dd:dd:152e/1282c19:dd:c25:c25f:dd4e:dd:dd:152e
482c19:dd:c25:c25f:dd4e:dd:dd:152f/1282c19:dd:c25:c25f:dd4e:dd:dd:152f
492c19:dd:c25:c25f:dd4e:dd:dd:1530/1282c19:dd:c25:c25f:dd4e:dd:dd:1530
502c19:dd:c25:c25f:dd4e:dd:dd:1531/1282c19:dd:c25:c25f:dd4e:dd:dd:1531
512c19:dd:c25:c25f:dd4e:dd:dd:1532/1282c19:dd:c25:c25f:dd4e:dd:dd:1532
522c19:dd:c25:c25f:dd4e:dd:dd:1533/1282c19:dd:c25:c25f:dd4e:dd:dd:1533
532c19:dd:c25:c25f:dd4e:dd:dd:1534/1282c19:dd:c25:c25f:dd4e:dd:dd:1534
542c19:dd:c25:c25f:dd4e:dd:dd:1535/1282c19:dd:c25:c25f:dd4e:dd:dd:1535
552c19:dd:c25:c25f:dd4e:dd:dd:1536/1282c19:dd:c25:c25f:dd4e:dd:dd:1536
562c19:dd:c25:c25f:dd4e:dd:dd:1537/1282c19:dd:c25:c25f:dd4e:dd:dd:1537
572c19:dd:c25:c25f:dd4e:dd:dd:1538/1282c19:dd:c25:c25f:dd4e:dd:dd:1538
582c19:dd:c25:c25f:dd4e:dd:dd:1539/1282c19:dd:c25:c25f:dd4e:dd:dd:1539
592c19:dd:c25:c25f:dd4e:dd:dd:153a/1282c19:dd:c25:c25f:dd4e:dd:dd:153a
602c19:dd:c25:c25f:dd4e:dd:dd:153b/1282c19:dd:c25:c25f:dd4e:dd:dd:153b
612c19:dd:c25:c25f:dd4e:dd:dd:153c/1282c19:dd:c25:c25f:dd4e:dd:dd:153c
622c19:dd:c25:c25f:dd4e:dd:dd:153d/1282c19:dd:c25:c25f:dd4e:dd:dd:153d
632c19:dd:c25:c25f:dd4e:dd:dd:153e/1282c19:dd:c25:c25f:dd4e:dd:dd:153e
642c19:dd:c25:c25f:dd4e:dd:dd:153f/1282c19:dd:c25:c25f:dd4e:dd:dd:153f
652c19:dd:c25:c25f:dd4e:dd:dd:1540/1282c19:dd:c25:c25f:dd4e:dd:dd:1540
662c19:dd:c25:c25f:dd4e:dd:dd:1541/1282c19:dd:c25:c25f:dd4e:dd:dd:1541
672c19:dd:c25:c25f:dd4e:dd:dd:1542/1282c19:dd:c25:c25f:dd4e:dd:dd:1542
682c19:dd:c25:c25f:dd4e:dd:dd:1543/1282c19:dd:c25:c25f:dd4e:dd:dd:1543
692c19:dd:c25:c25f:dd4e:dd:dd:1544/1282c19:dd:c25:c25f:dd4e:dd:dd:1544
702c19:dd:c25:c25f:dd4e:dd:dd:1545/1282c19:dd:c25:c25f:dd4e:dd:dd:1545
712c19:dd:c25:c25f:dd4e:dd:dd:1546/1282c19:dd:c25:c25f:dd4e:dd:dd:1546
722c19:dd:c25:c25f:dd4e:dd:dd:1547/1282c19:dd:c25:c25f:dd4e:dd:dd:1547
732c19:dd:c25:c25f:dd4e:dd:dd:1548/1282c19:dd:c25:c25f:dd4e:dd:dd:1548
742c19:dd:c25:c25f:dd4e:dd:dd:1549/1282c19:dd:c25:c25f:dd4e:dd:dd:1549
752c19:dd:c25:c25f:dd4e:dd:dd:154a/1282c19:dd:c25:c25f:dd4e:dd:dd:154a
762c19:dd:c25:c25f:dd4e:dd:dd:154b/1282c19:dd:c25:c25f:dd4e:dd:dd:154b
772c19:dd:c25:c25f:dd4e:dd:dd:154c/1282c19:dd:c25:c25f:dd4e:dd:dd:154c
782c19:dd:c25:c25f:dd4e:dd:dd:154d/1282c19:dd:c25:c25f:dd4e:dd:dd:154d
792c19:dd:c25:c25f:dd4e:dd:dd:154e/1282c19:dd:c25:c25f:dd4e:dd:dd:154e
802c19:dd:c25:c25f:dd4e:dd:dd:154f/1282c19:dd:c25:c25f:dd4e:dd:dd:154f
812c19:dd:c25:c25f:dd4e:dd:dd:1550/1282c19:dd:c25:c25f:dd4e:dd:dd:1550
822c19:dd:c25:c25f:dd4e:dd:dd:1551/1282c19:dd:c25:c25f:dd4e:dd:dd:1551
832c19:dd:c25:c25f:dd4e:dd:dd:1552/1282c19:dd:c25:c25f:dd4e:dd:dd:1552
842c19:dd:c25:c25f:dd4e:dd:dd:1553/1282c19:dd:c25:c25f:dd4e:dd:dd:1553
852c19:dd:c25:c25f:dd4e:dd:dd:1554/1282c19:dd:c25:c25f:dd4e:dd:dd:1554
862c19:dd:c25:c25f:dd4e:dd:dd:1555/1282c19:dd:c25:c25f:dd4e:dd:dd:1555
872c19:dd:c25:c25f:dd4e:dd:dd:1556/1282c19:dd:c25:c25f:dd4e:dd:dd:1556
882c19:dd:c25:c25f:dd4e:dd:dd:1557/1282c19:dd:c25:c25f:dd4e:dd:dd:1557
892c19:dd:c25:c25f:dd4e:dd:dd:1558/1282c19:dd:c25:c25f:dd4e:dd:dd:1558
902c19:dd:c25:c25f:dd4e:dd:dd:1559/1282c19:dd:c25:c25f:dd4e:dd:dd:1559
912c19:dd:c25:c25f:dd4e:dd:dd:155a/1282c19:dd:c25:c25f:dd4e:dd:dd:155a
922c19:dd:c25:c25f:dd4e:dd:dd:155b/1282c19:dd:c25:c25f:dd4e:dd:dd:155b
932c19:dd:c25:c25f:dd4e:dd:dd:155c/1282c19:dd:c25:c25f:dd4e:dd:dd:155c
942c19:dd:c25:c25f:dd4e:dd:dd:155d/1282c19:dd:c25:c25f:dd4e:dd:dd:155d
952c19:dd:c25:c25f:dd4e:dd:dd:155e/1282c19:dd:c25:c25f:dd4e:dd:dd:155e
962c19:dd:c25:c25f:dd4e:dd:dd:155f/1282c19:dd:c25:c25f:dd4e:dd:dd:155f
972c19:dd:c25:c25f:dd4e:dd:dd:1560/1282c19:dd:c25:c25f:dd4e:dd:dd:1560
982c19:dd:c25:c25f:dd4e:dd:dd:1561/1282c19:dd:c25:c25f:dd4e:dd:dd:1561
992c19:dd:c25:c25f:dd4e:dd:dd:1562/1282c19:dd:c25:c25f:dd4e:dd:dd:1562
1002c19:dd:c25:c25f:dd4e:dd:dd:1563/1282c19:dd:c25:c25f:dd4e:dd:dd:1563
1012c19:dd:c25:c25f:dd4e:dd:dd:1564/1282c19:dd:c25:c25f:dd4e:dd:dd:1564
1022c19:dd:c25:c25f:dd4e:dd:dd:1565/1282c19:dd:c25:c25f:dd4e:dd:dd:1565
1032c19:dd:c25:c25f:dd4e:dd:dd:1566/1282c19:dd:c25:c25f:dd4e:dd:dd:1566
1042c19:dd:c25:c25f:dd4e:dd:dd:1567/1282c19:dd:c25:c25f:dd4e:dd:dd:1567
1052c19:dd:c25:c25f:dd4e:dd:dd:1568/1282c19:dd:c25:c25f:dd4e:dd:dd:1568
1062c19:dd:c25:c25f:dd4e:dd:dd:1569/1282c19:dd:c25:c25f:dd4e:dd:dd:1569
1072c19:dd:c25:c25f:dd4e:dd:dd:156a/1282c19:dd:c25:c25f:dd4e:dd:dd:156a
1082c19:dd:c25:c25f:dd4e:dd:dd:156b/1282c19:dd:c25:c25f:dd4e:dd:dd:156b
1092c19:dd:c25:c25f:dd4e:dd:dd:156c/1282c19:dd:c25:c25f:dd4e:dd:dd:156c
1102c19:dd:c25:c25f:dd4e:dd:dd:156d/1282c19:dd:c25:c25f:dd4e:dd:dd:156d
1112c19:dd:c25:c25f:dd4e:dd:dd:156e/1282c19:dd:c25:c25f:dd4e:dd:dd:156e
1122c19:dd:c25:c25f:dd4e:dd:dd:156f/1282c19:dd:c25:c25f:dd4e:dd:dd:156f
1132c19:dd:c25:c25f:dd4e:dd:dd:1570/1282c19:dd:c25:c25f:dd4e:dd:dd:1570
1142c19:dd:c25:c25f:dd4e:dd:dd:1571/1282c19:dd:c25:c25f:dd4e:dd:dd:1571
1152c19:dd:c25:c25f:dd4e:dd:dd:1572/1282c19:dd:c25:c25f:dd4e:dd:dd:1572
1162c19:dd:c25:c25f:dd4e:dd:dd:1573/1282c19:dd:c25:c25f:dd4e:dd:dd:1573
1172c19:dd:c25:c25f:dd4e:dd:dd:1574/1282c19:dd:c25:c25f:dd4e:dd:dd:1574
1182c19:dd:c25:c25f:dd4e:dd:dd:1575/1282c19:dd:c25:c25f:dd4e:dd:dd:1575
1192c19:dd:c25:c25f:dd4e:dd:dd:1576/1282c19:dd:c25:c25f:dd4e:dd:dd:1576
1202c19:dd:c25:c25f:dd4e:dd:dd:1577/1282c19:dd:c25:c25f:dd4e:dd:dd:1577
1212c19:dd:c25:c25f:dd4e:dd:dd:1578/1282c19:dd:c25:c25f:dd4e:dd:dd:1578
1222c19:dd:c25:c25f:dd4e:dd:dd:1579/1282c19:dd:c25:c25f:dd4e:dd:dd:1579
1232c19:dd:c25:c25f:dd4e:dd:dd:157a/1282c19:dd:c25:c25f:dd4e:dd:dd:157a
1242c19:dd:c25:c25f:dd4e:dd:dd:157b/1282c19:dd:c25:c25f:dd4e:dd:dd:157b
1252c19:dd:c25:c25f:dd4e:dd:dd:157c/1282c19:dd:c25:c25f:dd4e:dd:dd:157c
1262c19:dd:c25:c25f:dd4e:dd:dd:157d/1282c19:dd:c25:c25f:dd4e:dd:dd:157d
1272c19:dd:c25:c25f:dd4e:dd:dd:157e/1282c19:dd:c25:c25f:dd4e:dd:dd:157e
1282c19:dd:c25:c25f:dd4e:dd:dd:157f/1282c19:dd:c25:c25f:dd4e:dd:dd:157f
1292c19:dd:c25:c25f:dd4e:dd:dd:1580/1282c19:dd:c25:c25f:dd4e:dd:dd:1580
1302c19:dd:c25:c25f:dd4e:dd:dd:1581/1282c19:dd:c25:c25f:dd4e:dd:dd:1581
1312c19:dd:c25:c25f:dd4e:dd:dd:1582/1282c19:dd:c25:c25f:dd4e:dd:dd:1582
1322c19:dd:c25:c25f:dd4e:dd:dd:1583/1282c19:dd:c25:c25f:dd4e:dd:dd:1583
1332c19:dd:c25:c25f:dd4e:dd:dd:1584/1282c19:dd:c25:c25f:dd4e:dd:dd:1584
1342c19:dd:c25:c25f:dd4e:dd:dd:1585/1282c19:dd:c25:c25f:dd4e:dd:dd:1585
1352c19:dd:c25:c25f:dd4e:dd:dd:1586/1282c19:dd:c25:c25f:dd4e:dd:dd:1586
1362c19:dd:c25:c25f:dd4e:dd:dd:1587/1282c19:dd:c25:c25f:dd4e:dd:dd:1587
1372c19:dd:c25:c25f:dd4e:dd:dd:1588/1282c19:dd:c25:c25f:dd4e:dd:dd:1588
1382c19:dd:c25:c25f:dd4e:dd:dd:1589/1282c19:dd:c25:c25f:dd4e:dd:dd:1589
1392c19:dd:c25:c25f:dd4e:dd:dd:158a/1282c19:dd:c25:c25f:dd4e:dd:dd:158a
1402c19:dd:c25:c25f:dd4e:dd:dd:158b/1282c19:dd:c25:c25f:dd4e:dd:dd:158b
1412c19:dd:c25:c25f:dd4e:dd:dd:158c/1282c19:dd:c25:c25f:dd4e:dd:dd:158c
1422c19:dd:c25:c25f:dd4e:dd:dd:158d/1282c19:dd:c25:c25f:dd4e:dd:dd:158d
1432c19:dd:c25:c25f:dd4e:dd:dd:158e/1282c19:dd:c25:c25f:dd4e:dd:dd:158e
1442c19:dd:c25:c25f:dd4e:dd:dd:158f/1282c19:dd:c25:c25f:dd4e:dd:dd:158f
1452c19:dd:c25:c25f:dd4e:dd:dd:1590/1282c19:dd:c25:c25f:dd4e:dd:dd:1590
1462c19:dd:c25:c25f:dd4e:dd:dd:1591/1282c19:dd:c25:c25f:dd4e:dd:dd:1591
1472c19:dd:c25:c25f:dd4e:dd:dd:1592/1282c19:dd:c25:c25f:dd4e:dd:dd:1592
1482c19:dd:c25:c25f:dd4e:dd:dd:1593/1282c19:dd:c25:c25f:dd4e:dd:dd:1593
1492c19:dd:c25:c25f:dd4e:dd:dd:1594/1282c19:dd:c25:c25f:dd4e:dd:dd:1594
1502c19:dd:c25:c25f:dd4e:dd:dd:1595/1282c19:dd:c25:c25f:dd4e:dd:dd:1595
1512c19:dd:c25:c25f:dd4e:dd:dd:1596/1282c19:dd:c25:c25f:dd4e:dd:dd:1596
1522c19:dd:c25:c25f:dd4e:dd:dd:1597/1282c19:dd:c25:c25f:dd4e:dd:dd:1597
1532c19:dd:c25:c25f:dd4e:dd:dd:1598/1282c19:dd:c25:c25f:dd4e:dd:dd:1598
1542c19:dd:c25:c25f:dd4e:dd:dd:1599/1282c19:dd:c25:c25f:dd4e:dd:dd:1599
1552c19:dd:c25:c25f:dd4e:dd:dd:159a/1282c19:dd:c25:c25f:dd4e:dd:dd:159a
1562c19:dd:c25:c25f:dd4e:dd:dd:159b/1282c19:dd:c25:c25f:dd4e:dd:dd:159b
1572c19:dd:c25:c25f:dd4e:dd:dd:159c/1282c19:dd:c25:c25f:dd4e:dd:dd:159c
1582c19:dd:c25:c25f:dd4e:dd:dd:159d/1282c19:dd:c25:c25f:dd4e:dd:dd:159d
1592c19:dd:c25:c25f:dd4e:dd:dd:159e/1282c19:dd:c25:c25f:dd4e:dd:dd:159e
1602c19:dd:c25:c25f:dd4e:dd:dd:159f/1282c19:dd:c25:c25f:dd4e:dd:dd:159f
1612c19:dd:c25:c25f:dd4e:dd:dd:15a0/1282c19:dd:c25:c25f:dd4e:dd:dd:15a0
1622c19:dd:c25:c25f:dd4e:dd:dd:15a1/1282c19:dd:c25:c25f:dd4e:dd:dd:15a1
1632c19:dd:c25:c25f:dd4e:dd:dd:15a2/1282c19:dd:c25:c25f:dd4e:dd:dd:15a2
1642c19:dd:c25:c25f:dd4e:dd:dd:15a3/1282c19:dd:c25:c25f:dd4e:dd:dd:15a3
1652c19:dd:c25:c25f:dd4e:dd:dd:15a4/1282c19:dd:c25:c25f:dd4e:dd:dd:15a4
1662c19:dd:c25:c25f:dd4e:dd:dd:15a5/1282c19:dd:c25:c25f:dd4e:dd:dd:15a5
1672c19:dd:c25:c25f:dd4e:dd:dd:15a6/1282c19:dd:c25:c25f:dd4e:dd:dd:15a6
1682c19:dd:c25:c25f:dd4e:dd:dd:15a7/1282c19:dd:c25:c25f:dd4e:dd:dd:15a7
1692c19:dd:c25:c25f:dd4e:dd:dd:15a8/1282c19:dd:c25:c25f:dd4e:dd:dd:15a8
1702c19:dd:c25:c25f:dd4e:dd:dd:15a9/1282c19:dd:c25:c25f:dd4e:dd:dd:15a9
1712c19:dd:c25:c25f:dd4e:dd:dd:15aa/1282c19:dd:c25:c25f:dd4e:dd:dd:15aa
1722c19:dd:c25:c25f:dd4e:dd:dd:15ab/1282c19:dd:c25:c25f:dd4e:dd:dd:15ab
1732c19:dd:c25:c25f:dd4e:dd:dd:15ac/1282c19:dd:c25:c25f:dd4e:dd:dd:15ac
1742c19:dd:c25:c25f:dd4e:dd:dd:15ad/1282c19:dd:c25:c25f:dd4e:dd:dd:15ad
1752c19:dd:c25:c25f:dd4e:dd:dd:15ae/1282c19:dd:c25:c25f:dd4e:dd:dd:15ae
1762c19:dd:c25:c25f:dd4e:dd:dd:15af/1282c19:dd:c25:c25f:dd4e:dd:dd:15af
1772c19:dd:c25:c25f:dd4e:dd:dd:15b0/1282c19:dd:c25:c25f:dd4e:dd:dd:15b0
1782c19:dd:c25:c25f:dd4e:dd:dd:15b1/1282c19:dd:c25:c25f:dd4e:dd:dd:15b1
1792c19:dd:c25:c25f:dd4e:dd:dd:15b2/1282c19:dd:c25:c25f:dd4e:dd:dd:15b2
1802c19:dd:c25:c25f:dd4e:dd:dd:15b3/1282c19:dd:c25:c25f:dd4e:dd:dd:15b3
1812c19:dd:c25:c25f:dd4e:dd:dd:15b4/1282c19:dd:c25:c25f:dd4e:dd:dd:15b4
1822c19:dd:c25:c25f:dd4e:dd:dd:15b5/1282c19:dd:c25:c25f:dd4e:dd:dd:15b5
1832c19:dd:c25:c25f:dd4e:dd:dd:15b6/1282c19:dd:c25:c25f:dd4e:dd:dd:15b6
1842c19:dd:c25:c25f:dd4e:dd:dd:15b7/1282c19:dd:c25:c25f:dd4e:dd:dd:15b7
1852c19:dd:c25:c25f:dd4e:dd:dd:15b8/1282c19:dd:c25:c25f:dd4e:dd:dd:15b8
1862c19:dd:c25:c25f:dd4e:dd:dd:15b9/1282c19:dd:c25:c25f:dd4e:dd:dd:15b9
1872c19:dd:c25:c25f:dd4e:dd:dd:15ba/1282c19:dd:c25:c25f:dd4e:dd:dd:15ba
1882c19:dd:c25:c25f:dd4e:dd:dd:15bb/1282c19:dd:c25:c25f:dd4e:dd:dd:15bb
1892c19:dd:c25:c25f:dd4e:dd:dd:15bc/1282c19:dd:c25:c25f:dd4e:dd:dd:15bc
1902c19:dd:c25:c25f:dd4e:dd:dd:15bd/1282c19:dd:c25:c25f:dd4e:dd:dd:15bd
1912c19:dd:c25:c25f:dd4e:dd:dd:15be/1282c19:dd:c25:c25f:dd4e:dd:dd:15be
1922c19:dd:c25:c25f:dd4e:dd:dd:15bf/1282c19:dd:c25:c25f:dd4e:dd:dd:15bf
1932c19:dd:c25:c25f:dd4e:dd:dd:15c0/1282c19:dd:c25:c25f:dd4e:dd:dd:15c0
1942c19:dd:c25:c25f:dd4e:dd:dd:15c1/1282c19:dd:c25:c25f:dd4e:dd:dd:15c1
1952c19:dd:c25:c25f:dd4e:dd:dd:15c2/1282c19:dd:c25:c25f:dd4e:dd:dd:15c2
1962c19:dd:c25:c25f:dd4e:dd:dd:15c3/1282c19:dd:c25:c25f:dd4e:dd:dd:15c3
1972c19:dd:c25:c25f:dd4e:dd:dd:15c4/1282c19:dd:c25:c25f:dd4e:dd:dd:15c4
1982c19:dd:c25:c25f:dd4e:dd:dd:15c5/1282c19:dd:c25:c25f:dd4e:dd:dd:15c5
1992c19:dd:c25:c25f:dd4e:dd:dd:15c6/1282c19:dd:c25:c25f:dd4e:dd:dd:15c6
2002c19:dd:c25:c25f:dd4e:dd:dd:15c7/1282c19:dd:c25:c25f:dd4e:dd:dd:15c7
2012c19:dd:c25:c25f:dd4e:dd:dd:15c8/1282c19:dd:c25:c25f:dd4e:dd:dd:15c8
2022c19:dd:c25:c25f:dd4e:dd:dd:15c9/1282c19:dd:c25:c25f:dd4e:dd:dd:15c9
2032c19:dd:c25:c25f:dd4e:dd:dd:15ca/1282c19:dd:c25:c25f:dd4e:dd:dd:15ca
2042c19:dd:c25:c25f:dd4e:dd:dd:15cb/1282c19:dd:c25:c25f:dd4e:dd:dd:15cb
2052c19:dd:c25:c25f:dd4e:dd:dd:15cc/1282c19:dd:c25:c25f:dd4e:dd:dd:15cc
2062c19:dd:c25:c25f:dd4e:dd:dd:15cd/1282c19:dd:c25:c25f:dd4e:dd:dd:15cd
2072c19:dd:c25:c25f:dd4e:dd:dd:15ce/1282c19:dd:c25:c25f:dd4e:dd:dd:15ce
2082c19:dd:c25:c25f:dd4e:dd:dd:15cf/1282c19:dd:c25:c25f:dd4e:dd:dd:15cf
2092c19:dd:c25:c25f:dd4e:dd:dd:15d0/1282c19:dd:c25:c25f:dd4e:dd:dd:15d0
2102c19:dd:c25:c25f:dd4e:dd:dd:15d1/1282c19:dd:c25:c25f:dd4e:dd:dd:15d1
2112c19:dd:c25:c25f:dd4e:dd:dd:15d2/1282c19:dd:c25:c25f:dd4e:dd:dd:15d2
2122c19:dd:c25:c25f:dd4e:dd:dd:15d3/1282c19:dd:c25:c25f:dd4e:dd:dd:15d3
2132c19:dd:c25:c25f:dd4e:dd:dd:15d4/1282c19:dd:c25:c25f:dd4e:dd:dd:15d4
2142c19:dd:c25:c25f:dd4e:dd:dd:15d5/1282c19:dd:c25:c25f:dd4e:dd:dd:15d5
2152c19:dd:c25:c25f:dd4e:dd:dd:15d6/1282c19:dd:c25:c25f:dd4e:dd:dd:15d6
2162c19:dd:c25:c25f:dd4e:dd:dd:15d7/1282c19:dd:c25:c25f:dd4e:dd:dd:15d7
2172c19:dd:c25:c25f:dd4e:dd:dd:15d8/1282c19:dd:c25:c25f:dd4e:dd:dd:15d8
2182c19:dd:c25:c25f:dd4e:dd:dd:15d9/1282c19:dd:c25:c25f:dd4e:dd:dd:15d9
2192c19:dd:c25:c25f:dd4e:dd:dd:15da/1282c19:dd:c25:c25f:dd4e:dd:dd:15da
2202c19:dd:c25:c25f:dd4e:dd:dd:15db/1282c19:dd:c25:c25f:dd4e:dd:dd:15db
2212c19:dd:c25:c25f:dd4e:dd:dd:15dc/1282c19:dd:c25:c25f:dd4e:dd:dd:15dc
2222c19:dd:c25:c25f:dd4e:dd:dd:15dd/1282c19:dd:c25:c25f:dd4e:dd:dd:15dd
2232c19:dd:c25:c25f:dd4e:dd:dd:15de/1282c19:dd:c25:c25f:dd4e:dd:dd:15de
2242c19:dd:c25:c25f:dd4e:dd:dd:15df/1282c19:dd:c25:c25f:dd4e:dd:dd:15df
2252c19:dd:c25:c25f:dd4e:dd:dd:15e0/1282c19:dd:c25:c25f:dd4e:dd:dd:15e0
2262c19:dd:c25:c25f:dd4e:dd:dd:15e1/1282c19:dd:c25:c25f:dd4e:dd:dd:15e1
2272c19:dd:c25:c25f:dd4e:dd:dd:15e2/1282c19:dd:c25:c25f:dd4e:dd:dd:15e2
2282c19:dd:c25:c25f:dd4e:dd:dd:15e3/1282c19:dd:c25:c25f:dd4e:dd:dd:15e3
2292c19:dd:c25:c25f:dd4e:dd:dd:15e4/1282c19:dd:c25:c25f:dd4e:dd:dd:15e4
2302c19:dd:c25:c25f:dd4e:dd:dd:15e5/1282c19:dd:c25:c25f:dd4e:dd:dd:15e5
2312c19:dd:c25:c25f:dd4e:dd:dd:15e6/1282c19:dd:c25:c25f:dd4e:dd:dd:15e6
2322c19:dd:c25:c25f:dd4e:dd:dd:15e7/1282c19:dd:c25:c25f:dd4e:dd:dd:15e7
2332c19:dd:c25:c25f:dd4e:dd:dd:15e8/1282c19:dd:c25:c25f:dd4e:dd:dd:15e8
2342c19:dd:c25:c25f:dd4e:dd:dd:15e9/1282c19:dd:c25:c25f:dd4e:dd:dd:15e9
2352c19:dd:c25:c25f:dd4e:dd:dd:15ea/1282c19:dd:c25:c25f:dd4e:dd:dd:15ea
2362c19:dd:c25:c25f:dd4e:dd:dd:15eb/1282c19:dd:c25:c25f:dd4e:dd:dd:15eb
2372c19:dd:c25:c25f:dd4e:dd:dd:15ec/1282c19:dd:c25:c25f:dd4e:dd:dd:15ec
2382c19:dd:c25:c25f:dd4e:dd:dd:15ed/1282c19:dd:c25:c25f:dd4e:dd:dd:15ed
2392c19:dd:c25:c25f:dd4e:dd:dd:15ee/1282c19:dd:c25:c25f:dd4e:dd:dd:15ee
2402c19:dd:c25:c25f:dd4e:dd:dd:15ef/1282c19:dd:c25:c25f:dd4e:dd:dd:15ef
2412c19:dd:c25:c25f:dd4e:dd:dd:15f0/1282c19:dd:c25:c25f:dd4e:dd:dd:15f0
2422c19:dd:c25:c25f:dd4e:dd:dd:15f1/1282c19:dd:c25:c25f:dd4e:dd:dd:15f1
2432c19:dd:c25:c25f:dd4e:dd:dd:15f2/1282c19:dd:c25:c25f:dd4e:dd:dd:15f2
2442c19:dd:c25:c25f:dd4e:dd:dd:15f3/1282c19:dd:c25:c25f:dd4e:dd:dd:15f3
2452c19:dd:c25:c25f:dd4e:dd:dd:15f4/1282c19:dd:c25:c25f:dd4e:dd:dd:15f4
2462c19:dd:c25:c25f:dd4e:dd:dd:15f5/1282c19:dd:c25:c25f:dd4e:dd:dd:15f5
2472c19:dd:c25:c25f:dd4e:dd:dd:15f6/1282c19:dd:c25:c25f:dd4e:dd:dd:15f6
2482c19:dd:c25:c25f:dd4e:dd:dd:15f7/1282c19:dd:c25:c25f:dd4e:dd:dd:15f7
2492c19:dd:c25:c25f:dd4e:dd:dd:15f8/1282c19:dd:c25:c25f:dd4e:dd:dd:15f8
2502c19:dd:c25:c25f:dd4e:dd:dd:15f9/1282c19:dd:c25:c25f:dd4e:dd:dd:15f9
2512c19:dd:c25:c25f:dd4e:dd:dd:15fa/1282c19:dd:c25:c25f:dd4e:dd:dd:15fa
2522c19:dd:c25:c25f:dd4e:dd:dd:15fb/1282c19:dd:c25:c25f:dd4e:dd:dd:15fb
2532c19:dd:c25:c25f:dd4e:dd:dd:15fc/1282c19:dd:c25:c25f:dd4e:dd:dd:15fc
2542c19:dd:c25:c25f:dd4e:dd:dd:15fd/1282c19:dd:c25:c25f:dd4e:dd:dd:15fd
2552c19:dd:c25:c25f:dd4e:dd:dd:15fe/1282c19:dd:c25:c25f:dd4e:dd:dd:15fe
2562c19:dd:c25:c25f:dd4e:dd:dd:15ff/1282c19:dd:c25:c25f:dd4e:dd:dd:15ff

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.