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:dde0:c500/120
First address
2c19:dd:d9:dd:c25:c25:dde0:c500
Last address
2c19:dd:d9:dd:c25:c25:dde0:c5ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:dde0:c500
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
5.c.0.e.d.d.5.2.c.0.5.2.c.0.d.d.0.0.9.d.0.0.d.d.0.0.9.1.c.2.ip6.arpa
Split into smaller subnets/128
/121 (2)/122 (4)/123 (8)/124 (16)/127 (128)/128 (256)

2c19:dd:d9:dd:c25:c25:dde0:c500/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:dde0:c500/1282c19:dd:d9:dd:c25:c25:dde0:c500
22c19:dd:d9:dd:c25:c25:dde0:c501/1282c19:dd:d9:dd:c25:c25:dde0:c501
32c19:dd:d9:dd:c25:c25:dde0:c502/1282c19:dd:d9:dd:c25:c25:dde0:c502
42c19:dd:d9:dd:c25:c25:dde0:c503/1282c19:dd:d9:dd:c25:c25:dde0:c503
52c19:dd:d9:dd:c25:c25:dde0:c504/1282c19:dd:d9:dd:c25:c25:dde0:c504
62c19:dd:d9:dd:c25:c25:dde0:c505/1282c19:dd:d9:dd:c25:c25:dde0:c505
72c19:dd:d9:dd:c25:c25:dde0:c506/1282c19:dd:d9:dd:c25:c25:dde0:c506
82c19:dd:d9:dd:c25:c25:dde0:c507/1282c19:dd:d9:dd:c25:c25:dde0:c507
92c19:dd:d9:dd:c25:c25:dde0:c508/1282c19:dd:d9:dd:c25:c25:dde0:c508
102c19:dd:d9:dd:c25:c25:dde0:c509/1282c19:dd:d9:dd:c25:c25:dde0:c509
112c19:dd:d9:dd:c25:c25:dde0:c50a/1282c19:dd:d9:dd:c25:c25:dde0:c50a
122c19:dd:d9:dd:c25:c25:dde0:c50b/1282c19:dd:d9:dd:c25:c25:dde0:c50b
132c19:dd:d9:dd:c25:c25:dde0:c50c/1282c19:dd:d9:dd:c25:c25:dde0:c50c
142c19:dd:d9:dd:c25:c25:dde0:c50d/1282c19:dd:d9:dd:c25:c25:dde0:c50d
152c19:dd:d9:dd:c25:c25:dde0:c50e/1282c19:dd:d9:dd:c25:c25:dde0:c50e
162c19:dd:d9:dd:c25:c25:dde0:c50f/1282c19:dd:d9:dd:c25:c25:dde0:c50f
172c19:dd:d9:dd:c25:c25:dde0:c510/1282c19:dd:d9:dd:c25:c25:dde0:c510
182c19:dd:d9:dd:c25:c25:dde0:c511/1282c19:dd:d9:dd:c25:c25:dde0:c511
192c19:dd:d9:dd:c25:c25:dde0:c512/1282c19:dd:d9:dd:c25:c25:dde0:c512
202c19:dd:d9:dd:c25:c25:dde0:c513/1282c19:dd:d9:dd:c25:c25:dde0:c513
212c19:dd:d9:dd:c25:c25:dde0:c514/1282c19:dd:d9:dd:c25:c25:dde0:c514
222c19:dd:d9:dd:c25:c25:dde0:c515/1282c19:dd:d9:dd:c25:c25:dde0:c515
232c19:dd:d9:dd:c25:c25:dde0:c516/1282c19:dd:d9:dd:c25:c25:dde0:c516
242c19:dd:d9:dd:c25:c25:dde0:c517/1282c19:dd:d9:dd:c25:c25:dde0:c517
252c19:dd:d9:dd:c25:c25:dde0:c518/1282c19:dd:d9:dd:c25:c25:dde0:c518
262c19:dd:d9:dd:c25:c25:dde0:c519/1282c19:dd:d9:dd:c25:c25:dde0:c519
272c19:dd:d9:dd:c25:c25:dde0:c51a/1282c19:dd:d9:dd:c25:c25:dde0:c51a
282c19:dd:d9:dd:c25:c25:dde0:c51b/1282c19:dd:d9:dd:c25:c25:dde0:c51b
292c19:dd:d9:dd:c25:c25:dde0:c51c/1282c19:dd:d9:dd:c25:c25:dde0:c51c
302c19:dd:d9:dd:c25:c25:dde0:c51d/1282c19:dd:d9:dd:c25:c25:dde0:c51d
312c19:dd:d9:dd:c25:c25:dde0:c51e/1282c19:dd:d9:dd:c25:c25:dde0:c51e
322c19:dd:d9:dd:c25:c25:dde0:c51f/1282c19:dd:d9:dd:c25:c25:dde0:c51f
332c19:dd:d9:dd:c25:c25:dde0:c520/1282c19:dd:d9:dd:c25:c25:dde0:c520
342c19:dd:d9:dd:c25:c25:dde0:c521/1282c19:dd:d9:dd:c25:c25:dde0:c521
352c19:dd:d9:dd:c25:c25:dde0:c522/1282c19:dd:d9:dd:c25:c25:dde0:c522
362c19:dd:d9:dd:c25:c25:dde0:c523/1282c19:dd:d9:dd:c25:c25:dde0:c523
372c19:dd:d9:dd:c25:c25:dde0:c524/1282c19:dd:d9:dd:c25:c25:dde0:c524
382c19:dd:d9:dd:c25:c25:dde0:c525/1282c19:dd:d9:dd:c25:c25:dde0:c525
392c19:dd:d9:dd:c25:c25:dde0:c526/1282c19:dd:d9:dd:c25:c25:dde0:c526
402c19:dd:d9:dd:c25:c25:dde0:c527/1282c19:dd:d9:dd:c25:c25:dde0:c527
412c19:dd:d9:dd:c25:c25:dde0:c528/1282c19:dd:d9:dd:c25:c25:dde0:c528
422c19:dd:d9:dd:c25:c25:dde0:c529/1282c19:dd:d9:dd:c25:c25:dde0:c529
432c19:dd:d9:dd:c25:c25:dde0:c52a/1282c19:dd:d9:dd:c25:c25:dde0:c52a
442c19:dd:d9:dd:c25:c25:dde0:c52b/1282c19:dd:d9:dd:c25:c25:dde0:c52b
452c19:dd:d9:dd:c25:c25:dde0:c52c/1282c19:dd:d9:dd:c25:c25:dde0:c52c
462c19:dd:d9:dd:c25:c25:dde0:c52d/1282c19:dd:d9:dd:c25:c25:dde0:c52d
472c19:dd:d9:dd:c25:c25:dde0:c52e/1282c19:dd:d9:dd:c25:c25:dde0:c52e
482c19:dd:d9:dd:c25:c25:dde0:c52f/1282c19:dd:d9:dd:c25:c25:dde0:c52f
492c19:dd:d9:dd:c25:c25:dde0:c530/1282c19:dd:d9:dd:c25:c25:dde0:c530
502c19:dd:d9:dd:c25:c25:dde0:c531/1282c19:dd:d9:dd:c25:c25:dde0:c531
512c19:dd:d9:dd:c25:c25:dde0:c532/1282c19:dd:d9:dd:c25:c25:dde0:c532
522c19:dd:d9:dd:c25:c25:dde0:c533/1282c19:dd:d9:dd:c25:c25:dde0:c533
532c19:dd:d9:dd:c25:c25:dde0:c534/1282c19:dd:d9:dd:c25:c25:dde0:c534
542c19:dd:d9:dd:c25:c25:dde0:c535/1282c19:dd:d9:dd:c25:c25:dde0:c535
552c19:dd:d9:dd:c25:c25:dde0:c536/1282c19:dd:d9:dd:c25:c25:dde0:c536
562c19:dd:d9:dd:c25:c25:dde0:c537/1282c19:dd:d9:dd:c25:c25:dde0:c537
572c19:dd:d9:dd:c25:c25:dde0:c538/1282c19:dd:d9:dd:c25:c25:dde0:c538
582c19:dd:d9:dd:c25:c25:dde0:c539/1282c19:dd:d9:dd:c25:c25:dde0:c539
592c19:dd:d9:dd:c25:c25:dde0:c53a/1282c19:dd:d9:dd:c25:c25:dde0:c53a
602c19:dd:d9:dd:c25:c25:dde0:c53b/1282c19:dd:d9:dd:c25:c25:dde0:c53b
612c19:dd:d9:dd:c25:c25:dde0:c53c/1282c19:dd:d9:dd:c25:c25:dde0:c53c
622c19:dd:d9:dd:c25:c25:dde0:c53d/1282c19:dd:d9:dd:c25:c25:dde0:c53d
632c19:dd:d9:dd:c25:c25:dde0:c53e/1282c19:dd:d9:dd:c25:c25:dde0:c53e
642c19:dd:d9:dd:c25:c25:dde0:c53f/1282c19:dd:d9:dd:c25:c25:dde0:c53f
652c19:dd:d9:dd:c25:c25:dde0:c540/1282c19:dd:d9:dd:c25:c25:dde0:c540
662c19:dd:d9:dd:c25:c25:dde0:c541/1282c19:dd:d9:dd:c25:c25:dde0:c541
672c19:dd:d9:dd:c25:c25:dde0:c542/1282c19:dd:d9:dd:c25:c25:dde0:c542
682c19:dd:d9:dd:c25:c25:dde0:c543/1282c19:dd:d9:dd:c25:c25:dde0:c543
692c19:dd:d9:dd:c25:c25:dde0:c544/1282c19:dd:d9:dd:c25:c25:dde0:c544
702c19:dd:d9:dd:c25:c25:dde0:c545/1282c19:dd:d9:dd:c25:c25:dde0:c545
712c19:dd:d9:dd:c25:c25:dde0:c546/1282c19:dd:d9:dd:c25:c25:dde0:c546
722c19:dd:d9:dd:c25:c25:dde0:c547/1282c19:dd:d9:dd:c25:c25:dde0:c547
732c19:dd:d9:dd:c25:c25:dde0:c548/1282c19:dd:d9:dd:c25:c25:dde0:c548
742c19:dd:d9:dd:c25:c25:dde0:c549/1282c19:dd:d9:dd:c25:c25:dde0:c549
752c19:dd:d9:dd:c25:c25:dde0:c54a/1282c19:dd:d9:dd:c25:c25:dde0:c54a
762c19:dd:d9:dd:c25:c25:dde0:c54b/1282c19:dd:d9:dd:c25:c25:dde0:c54b
772c19:dd:d9:dd:c25:c25:dde0:c54c/1282c19:dd:d9:dd:c25:c25:dde0:c54c
782c19:dd:d9:dd:c25:c25:dde0:c54d/1282c19:dd:d9:dd:c25:c25:dde0:c54d
792c19:dd:d9:dd:c25:c25:dde0:c54e/1282c19:dd:d9:dd:c25:c25:dde0:c54e
802c19:dd:d9:dd:c25:c25:dde0:c54f/1282c19:dd:d9:dd:c25:c25:dde0:c54f
812c19:dd:d9:dd:c25:c25:dde0:c550/1282c19:dd:d9:dd:c25:c25:dde0:c550
822c19:dd:d9:dd:c25:c25:dde0:c551/1282c19:dd:d9:dd:c25:c25:dde0:c551
832c19:dd:d9:dd:c25:c25:dde0:c552/1282c19:dd:d9:dd:c25:c25:dde0:c552
842c19:dd:d9:dd:c25:c25:dde0:c553/1282c19:dd:d9:dd:c25:c25:dde0:c553
852c19:dd:d9:dd:c25:c25:dde0:c554/1282c19:dd:d9:dd:c25:c25:dde0:c554
862c19:dd:d9:dd:c25:c25:dde0:c555/1282c19:dd:d9:dd:c25:c25:dde0:c555
872c19:dd:d9:dd:c25:c25:dde0:c556/1282c19:dd:d9:dd:c25:c25:dde0:c556
882c19:dd:d9:dd:c25:c25:dde0:c557/1282c19:dd:d9:dd:c25:c25:dde0:c557
892c19:dd:d9:dd:c25:c25:dde0:c558/1282c19:dd:d9:dd:c25:c25:dde0:c558
902c19:dd:d9:dd:c25:c25:dde0:c559/1282c19:dd:d9:dd:c25:c25:dde0:c559
912c19:dd:d9:dd:c25:c25:dde0:c55a/1282c19:dd:d9:dd:c25:c25:dde0:c55a
922c19:dd:d9:dd:c25:c25:dde0:c55b/1282c19:dd:d9:dd:c25:c25:dde0:c55b
932c19:dd:d9:dd:c25:c25:dde0:c55c/1282c19:dd:d9:dd:c25:c25:dde0:c55c
942c19:dd:d9:dd:c25:c25:dde0:c55d/1282c19:dd:d9:dd:c25:c25:dde0:c55d
952c19:dd:d9:dd:c25:c25:dde0:c55e/1282c19:dd:d9:dd:c25:c25:dde0:c55e
962c19:dd:d9:dd:c25:c25:dde0:c55f/1282c19:dd:d9:dd:c25:c25:dde0:c55f
972c19:dd:d9:dd:c25:c25:dde0:c560/1282c19:dd:d9:dd:c25:c25:dde0:c560
982c19:dd:d9:dd:c25:c25:dde0:c561/1282c19:dd:d9:dd:c25:c25:dde0:c561
992c19:dd:d9:dd:c25:c25:dde0:c562/1282c19:dd:d9:dd:c25:c25:dde0:c562
1002c19:dd:d9:dd:c25:c25:dde0:c563/1282c19:dd:d9:dd:c25:c25:dde0:c563
1012c19:dd:d9:dd:c25:c25:dde0:c564/1282c19:dd:d9:dd:c25:c25:dde0:c564
1022c19:dd:d9:dd:c25:c25:dde0:c565/1282c19:dd:d9:dd:c25:c25:dde0:c565
1032c19:dd:d9:dd:c25:c25:dde0:c566/1282c19:dd:d9:dd:c25:c25:dde0:c566
1042c19:dd:d9:dd:c25:c25:dde0:c567/1282c19:dd:d9:dd:c25:c25:dde0:c567
1052c19:dd:d9:dd:c25:c25:dde0:c568/1282c19:dd:d9:dd:c25:c25:dde0:c568
1062c19:dd:d9:dd:c25:c25:dde0:c569/1282c19:dd:d9:dd:c25:c25:dde0:c569
1072c19:dd:d9:dd:c25:c25:dde0:c56a/1282c19:dd:d9:dd:c25:c25:dde0:c56a
1082c19:dd:d9:dd:c25:c25:dde0:c56b/1282c19:dd:d9:dd:c25:c25:dde0:c56b
1092c19:dd:d9:dd:c25:c25:dde0:c56c/1282c19:dd:d9:dd:c25:c25:dde0:c56c
1102c19:dd:d9:dd:c25:c25:dde0:c56d/1282c19:dd:d9:dd:c25:c25:dde0:c56d
1112c19:dd:d9:dd:c25:c25:dde0:c56e/1282c19:dd:d9:dd:c25:c25:dde0:c56e
1122c19:dd:d9:dd:c25:c25:dde0:c56f/1282c19:dd:d9:dd:c25:c25:dde0:c56f
1132c19:dd:d9:dd:c25:c25:dde0:c570/1282c19:dd:d9:dd:c25:c25:dde0:c570
1142c19:dd:d9:dd:c25:c25:dde0:c571/1282c19:dd:d9:dd:c25:c25:dde0:c571
1152c19:dd:d9:dd:c25:c25:dde0:c572/1282c19:dd:d9:dd:c25:c25:dde0:c572
1162c19:dd:d9:dd:c25:c25:dde0:c573/1282c19:dd:d9:dd:c25:c25:dde0:c573
1172c19:dd:d9:dd:c25:c25:dde0:c574/1282c19:dd:d9:dd:c25:c25:dde0:c574
1182c19:dd:d9:dd:c25:c25:dde0:c575/1282c19:dd:d9:dd:c25:c25:dde0:c575
1192c19:dd:d9:dd:c25:c25:dde0:c576/1282c19:dd:d9:dd:c25:c25:dde0:c576
1202c19:dd:d9:dd:c25:c25:dde0:c577/1282c19:dd:d9:dd:c25:c25:dde0:c577
1212c19:dd:d9:dd:c25:c25:dde0:c578/1282c19:dd:d9:dd:c25:c25:dde0:c578
1222c19:dd:d9:dd:c25:c25:dde0:c579/1282c19:dd:d9:dd:c25:c25:dde0:c579
1232c19:dd:d9:dd:c25:c25:dde0:c57a/1282c19:dd:d9:dd:c25:c25:dde0:c57a
1242c19:dd:d9:dd:c25:c25:dde0:c57b/1282c19:dd:d9:dd:c25:c25:dde0:c57b
1252c19:dd:d9:dd:c25:c25:dde0:c57c/1282c19:dd:d9:dd:c25:c25:dde0:c57c
1262c19:dd:d9:dd:c25:c25:dde0:c57d/1282c19:dd:d9:dd:c25:c25:dde0:c57d
1272c19:dd:d9:dd:c25:c25:dde0:c57e/1282c19:dd:d9:dd:c25:c25:dde0:c57e
1282c19:dd:d9:dd:c25:c25:dde0:c57f/1282c19:dd:d9:dd:c25:c25:dde0:c57f
1292c19:dd:d9:dd:c25:c25:dde0:c580/1282c19:dd:d9:dd:c25:c25:dde0:c580
1302c19:dd:d9:dd:c25:c25:dde0:c581/1282c19:dd:d9:dd:c25:c25:dde0:c581
1312c19:dd:d9:dd:c25:c25:dde0:c582/1282c19:dd:d9:dd:c25:c25:dde0:c582
1322c19:dd:d9:dd:c25:c25:dde0:c583/1282c19:dd:d9:dd:c25:c25:dde0:c583
1332c19:dd:d9:dd:c25:c25:dde0:c584/1282c19:dd:d9:dd:c25:c25:dde0:c584
1342c19:dd:d9:dd:c25:c25:dde0:c585/1282c19:dd:d9:dd:c25:c25:dde0:c585
1352c19:dd:d9:dd:c25:c25:dde0:c586/1282c19:dd:d9:dd:c25:c25:dde0:c586
1362c19:dd:d9:dd:c25:c25:dde0:c587/1282c19:dd:d9:dd:c25:c25:dde0:c587
1372c19:dd:d9:dd:c25:c25:dde0:c588/1282c19:dd:d9:dd:c25:c25:dde0:c588
1382c19:dd:d9:dd:c25:c25:dde0:c589/1282c19:dd:d9:dd:c25:c25:dde0:c589
1392c19:dd:d9:dd:c25:c25:dde0:c58a/1282c19:dd:d9:dd:c25:c25:dde0:c58a
1402c19:dd:d9:dd:c25:c25:dde0:c58b/1282c19:dd:d9:dd:c25:c25:dde0:c58b
1412c19:dd:d9:dd:c25:c25:dde0:c58c/1282c19:dd:d9:dd:c25:c25:dde0:c58c
1422c19:dd:d9:dd:c25:c25:dde0:c58d/1282c19:dd:d9:dd:c25:c25:dde0:c58d
1432c19:dd:d9:dd:c25:c25:dde0:c58e/1282c19:dd:d9:dd:c25:c25:dde0:c58e
1442c19:dd:d9:dd:c25:c25:dde0:c58f/1282c19:dd:d9:dd:c25:c25:dde0:c58f
1452c19:dd:d9:dd:c25:c25:dde0:c590/1282c19:dd:d9:dd:c25:c25:dde0:c590
1462c19:dd:d9:dd:c25:c25:dde0:c591/1282c19:dd:d9:dd:c25:c25:dde0:c591
1472c19:dd:d9:dd:c25:c25:dde0:c592/1282c19:dd:d9:dd:c25:c25:dde0:c592
1482c19:dd:d9:dd:c25:c25:dde0:c593/1282c19:dd:d9:dd:c25:c25:dde0:c593
1492c19:dd:d9:dd:c25:c25:dde0:c594/1282c19:dd:d9:dd:c25:c25:dde0:c594
1502c19:dd:d9:dd:c25:c25:dde0:c595/1282c19:dd:d9:dd:c25:c25:dde0:c595
1512c19:dd:d9:dd:c25:c25:dde0:c596/1282c19:dd:d9:dd:c25:c25:dde0:c596
1522c19:dd:d9:dd:c25:c25:dde0:c597/1282c19:dd:d9:dd:c25:c25:dde0:c597
1532c19:dd:d9:dd:c25:c25:dde0:c598/1282c19:dd:d9:dd:c25:c25:dde0:c598
1542c19:dd:d9:dd:c25:c25:dde0:c599/1282c19:dd:d9:dd:c25:c25:dde0:c599
1552c19:dd:d9:dd:c25:c25:dde0:c59a/1282c19:dd:d9:dd:c25:c25:dde0:c59a
1562c19:dd:d9:dd:c25:c25:dde0:c59b/1282c19:dd:d9:dd:c25:c25:dde0:c59b
1572c19:dd:d9:dd:c25:c25:dde0:c59c/1282c19:dd:d9:dd:c25:c25:dde0:c59c
1582c19:dd:d9:dd:c25:c25:dde0:c59d/1282c19:dd:d9:dd:c25:c25:dde0:c59d
1592c19:dd:d9:dd:c25:c25:dde0:c59e/1282c19:dd:d9:dd:c25:c25:dde0:c59e
1602c19:dd:d9:dd:c25:c25:dde0:c59f/1282c19:dd:d9:dd:c25:c25:dde0:c59f
1612c19:dd:d9:dd:c25:c25:dde0:c5a0/1282c19:dd:d9:dd:c25:c25:dde0:c5a0
1622c19:dd:d9:dd:c25:c25:dde0:c5a1/1282c19:dd:d9:dd:c25:c25:dde0:c5a1
1632c19:dd:d9:dd:c25:c25:dde0:c5a2/1282c19:dd:d9:dd:c25:c25:dde0:c5a2
1642c19:dd:d9:dd:c25:c25:dde0:c5a3/1282c19:dd:d9:dd:c25:c25:dde0:c5a3
1652c19:dd:d9:dd:c25:c25:dde0:c5a4/1282c19:dd:d9:dd:c25:c25:dde0:c5a4
1662c19:dd:d9:dd:c25:c25:dde0:c5a5/1282c19:dd:d9:dd:c25:c25:dde0:c5a5
1672c19:dd:d9:dd:c25:c25:dde0:c5a6/1282c19:dd:d9:dd:c25:c25:dde0:c5a6
1682c19:dd:d9:dd:c25:c25:dde0:c5a7/1282c19:dd:d9:dd:c25:c25:dde0:c5a7
1692c19:dd:d9:dd:c25:c25:dde0:c5a8/1282c19:dd:d9:dd:c25:c25:dde0:c5a8
1702c19:dd:d9:dd:c25:c25:dde0:c5a9/1282c19:dd:d9:dd:c25:c25:dde0:c5a9
1712c19:dd:d9:dd:c25:c25:dde0:c5aa/1282c19:dd:d9:dd:c25:c25:dde0:c5aa
1722c19:dd:d9:dd:c25:c25:dde0:c5ab/1282c19:dd:d9:dd:c25:c25:dde0:c5ab
1732c19:dd:d9:dd:c25:c25:dde0:c5ac/1282c19:dd:d9:dd:c25:c25:dde0:c5ac
1742c19:dd:d9:dd:c25:c25:dde0:c5ad/1282c19:dd:d9:dd:c25:c25:dde0:c5ad
1752c19:dd:d9:dd:c25:c25:dde0:c5ae/1282c19:dd:d9:dd:c25:c25:dde0:c5ae
1762c19:dd:d9:dd:c25:c25:dde0:c5af/1282c19:dd:d9:dd:c25:c25:dde0:c5af
1772c19:dd:d9:dd:c25:c25:dde0:c5b0/1282c19:dd:d9:dd:c25:c25:dde0:c5b0
1782c19:dd:d9:dd:c25:c25:dde0:c5b1/1282c19:dd:d9:dd:c25:c25:dde0:c5b1
1792c19:dd:d9:dd:c25:c25:dde0:c5b2/1282c19:dd:d9:dd:c25:c25:dde0:c5b2
1802c19:dd:d9:dd:c25:c25:dde0:c5b3/1282c19:dd:d9:dd:c25:c25:dde0:c5b3
1812c19:dd:d9:dd:c25:c25:dde0:c5b4/1282c19:dd:d9:dd:c25:c25:dde0:c5b4
1822c19:dd:d9:dd:c25:c25:dde0:c5b5/1282c19:dd:d9:dd:c25:c25:dde0:c5b5
1832c19:dd:d9:dd:c25:c25:dde0:c5b6/1282c19:dd:d9:dd:c25:c25:dde0:c5b6
1842c19:dd:d9:dd:c25:c25:dde0:c5b7/1282c19:dd:d9:dd:c25:c25:dde0:c5b7
1852c19:dd:d9:dd:c25:c25:dde0:c5b8/1282c19:dd:d9:dd:c25:c25:dde0:c5b8
1862c19:dd:d9:dd:c25:c25:dde0:c5b9/1282c19:dd:d9:dd:c25:c25:dde0:c5b9
1872c19:dd:d9:dd:c25:c25:dde0:c5ba/1282c19:dd:d9:dd:c25:c25:dde0:c5ba
1882c19:dd:d9:dd:c25:c25:dde0:c5bb/1282c19:dd:d9:dd:c25:c25:dde0:c5bb
1892c19:dd:d9:dd:c25:c25:dde0:c5bc/1282c19:dd:d9:dd:c25:c25:dde0:c5bc
1902c19:dd:d9:dd:c25:c25:dde0:c5bd/1282c19:dd:d9:dd:c25:c25:dde0:c5bd
1912c19:dd:d9:dd:c25:c25:dde0:c5be/1282c19:dd:d9:dd:c25:c25:dde0:c5be
1922c19:dd:d9:dd:c25:c25:dde0:c5bf/1282c19:dd:d9:dd:c25:c25:dde0:c5bf
1932c19:dd:d9:dd:c25:c25:dde0:c5c0/1282c19:dd:d9:dd:c25:c25:dde0:c5c0
1942c19:dd:d9:dd:c25:c25:dde0:c5c1/1282c19:dd:d9:dd:c25:c25:dde0:c5c1
1952c19:dd:d9:dd:c25:c25:dde0:c5c2/1282c19:dd:d9:dd:c25:c25:dde0:c5c2
1962c19:dd:d9:dd:c25:c25:dde0:c5c3/1282c19:dd:d9:dd:c25:c25:dde0:c5c3
1972c19:dd:d9:dd:c25:c25:dde0:c5c4/1282c19:dd:d9:dd:c25:c25:dde0:c5c4
1982c19:dd:d9:dd:c25:c25:dde0:c5c5/1282c19:dd:d9:dd:c25:c25:dde0:c5c5
1992c19:dd:d9:dd:c25:c25:dde0:c5c6/1282c19:dd:d9:dd:c25:c25:dde0:c5c6
2002c19:dd:d9:dd:c25:c25:dde0:c5c7/1282c19:dd:d9:dd:c25:c25:dde0:c5c7
2012c19:dd:d9:dd:c25:c25:dde0:c5c8/1282c19:dd:d9:dd:c25:c25:dde0:c5c8
2022c19:dd:d9:dd:c25:c25:dde0:c5c9/1282c19:dd:d9:dd:c25:c25:dde0:c5c9
2032c19:dd:d9:dd:c25:c25:dde0:c5ca/1282c19:dd:d9:dd:c25:c25:dde0:c5ca
2042c19:dd:d9:dd:c25:c25:dde0:c5cb/1282c19:dd:d9:dd:c25:c25:dde0:c5cb
2052c19:dd:d9:dd:c25:c25:dde0:c5cc/1282c19:dd:d9:dd:c25:c25:dde0:c5cc
2062c19:dd:d9:dd:c25:c25:dde0:c5cd/1282c19:dd:d9:dd:c25:c25:dde0:c5cd
2072c19:dd:d9:dd:c25:c25:dde0:c5ce/1282c19:dd:d9:dd:c25:c25:dde0:c5ce
2082c19:dd:d9:dd:c25:c25:dde0:c5cf/1282c19:dd:d9:dd:c25:c25:dde0:c5cf
2092c19:dd:d9:dd:c25:c25:dde0:c5d0/1282c19:dd:d9:dd:c25:c25:dde0:c5d0
2102c19:dd:d9:dd:c25:c25:dde0:c5d1/1282c19:dd:d9:dd:c25:c25:dde0:c5d1
2112c19:dd:d9:dd:c25:c25:dde0:c5d2/1282c19:dd:d9:dd:c25:c25:dde0:c5d2
2122c19:dd:d9:dd:c25:c25:dde0:c5d3/1282c19:dd:d9:dd:c25:c25:dde0:c5d3
2132c19:dd:d9:dd:c25:c25:dde0:c5d4/1282c19:dd:d9:dd:c25:c25:dde0:c5d4
2142c19:dd:d9:dd:c25:c25:dde0:c5d5/1282c19:dd:d9:dd:c25:c25:dde0:c5d5
2152c19:dd:d9:dd:c25:c25:dde0:c5d6/1282c19:dd:d9:dd:c25:c25:dde0:c5d6
2162c19:dd:d9:dd:c25:c25:dde0:c5d7/1282c19:dd:d9:dd:c25:c25:dde0:c5d7
2172c19:dd:d9:dd:c25:c25:dde0:c5d8/1282c19:dd:d9:dd:c25:c25:dde0:c5d8
2182c19:dd:d9:dd:c25:c25:dde0:c5d9/1282c19:dd:d9:dd:c25:c25:dde0:c5d9
2192c19:dd:d9:dd:c25:c25:dde0:c5da/1282c19:dd:d9:dd:c25:c25:dde0:c5da
2202c19:dd:d9:dd:c25:c25:dde0:c5db/1282c19:dd:d9:dd:c25:c25:dde0:c5db
2212c19:dd:d9:dd:c25:c25:dde0:c5dc/1282c19:dd:d9:dd:c25:c25:dde0:c5dc
2222c19:dd:d9:dd:c25:c25:dde0:c5dd/1282c19:dd:d9:dd:c25:c25:dde0:c5dd
2232c19:dd:d9:dd:c25:c25:dde0:c5de/1282c19:dd:d9:dd:c25:c25:dde0:c5de
2242c19:dd:d9:dd:c25:c25:dde0:c5df/1282c19:dd:d9:dd:c25:c25:dde0:c5df
2252c19:dd:d9:dd:c25:c25:dde0:c5e0/1282c19:dd:d9:dd:c25:c25:dde0:c5e0
2262c19:dd:d9:dd:c25:c25:dde0:c5e1/1282c19:dd:d9:dd:c25:c25:dde0:c5e1
2272c19:dd:d9:dd:c25:c25:dde0:c5e2/1282c19:dd:d9:dd:c25:c25:dde0:c5e2
2282c19:dd:d9:dd:c25:c25:dde0:c5e3/1282c19:dd:d9:dd:c25:c25:dde0:c5e3
2292c19:dd:d9:dd:c25:c25:dde0:c5e4/1282c19:dd:d9:dd:c25:c25:dde0:c5e4
2302c19:dd:d9:dd:c25:c25:dde0:c5e5/1282c19:dd:d9:dd:c25:c25:dde0:c5e5
2312c19:dd:d9:dd:c25:c25:dde0:c5e6/1282c19:dd:d9:dd:c25:c25:dde0:c5e6
2322c19:dd:d9:dd:c25:c25:dde0:c5e7/1282c19:dd:d9:dd:c25:c25:dde0:c5e7
2332c19:dd:d9:dd:c25:c25:dde0:c5e8/1282c19:dd:d9:dd:c25:c25:dde0:c5e8
2342c19:dd:d9:dd:c25:c25:dde0:c5e9/1282c19:dd:d9:dd:c25:c25:dde0:c5e9
2352c19:dd:d9:dd:c25:c25:dde0:c5ea/1282c19:dd:d9:dd:c25:c25:dde0:c5ea
2362c19:dd:d9:dd:c25:c25:dde0:c5eb/1282c19:dd:d9:dd:c25:c25:dde0:c5eb
2372c19:dd:d9:dd:c25:c25:dde0:c5ec/1282c19:dd:d9:dd:c25:c25:dde0:c5ec
2382c19:dd:d9:dd:c25:c25:dde0:c5ed/1282c19:dd:d9:dd:c25:c25:dde0:c5ed
2392c19:dd:d9:dd:c25:c25:dde0:c5ee/1282c19:dd:d9:dd:c25:c25:dde0:c5ee
2402c19:dd:d9:dd:c25:c25:dde0:c5ef/1282c19:dd:d9:dd:c25:c25:dde0:c5ef
2412c19:dd:d9:dd:c25:c25:dde0:c5f0/1282c19:dd:d9:dd:c25:c25:dde0:c5f0
2422c19:dd:d9:dd:c25:c25:dde0:c5f1/1282c19:dd:d9:dd:c25:c25:dde0:c5f1
2432c19:dd:d9:dd:c25:c25:dde0:c5f2/1282c19:dd:d9:dd:c25:c25:dde0:c5f2
2442c19:dd:d9:dd:c25:c25:dde0:c5f3/1282c19:dd:d9:dd:c25:c25:dde0:c5f3
2452c19:dd:d9:dd:c25:c25:dde0:c5f4/1282c19:dd:d9:dd:c25:c25:dde0:c5f4
2462c19:dd:d9:dd:c25:c25:dde0:c5f5/1282c19:dd:d9:dd:c25:c25:dde0:c5f5
2472c19:dd:d9:dd:c25:c25:dde0:c5f6/1282c19:dd:d9:dd:c25:c25:dde0:c5f6
2482c19:dd:d9:dd:c25:c25:dde0:c5f7/1282c19:dd:d9:dd:c25:c25:dde0:c5f7
2492c19:dd:d9:dd:c25:c25:dde0:c5f8/1282c19:dd:d9:dd:c25:c25:dde0:c5f8
2502c19:dd:d9:dd:c25:c25:dde0:c5f9/1282c19:dd:d9:dd:c25:c25:dde0:c5f9
2512c19:dd:d9:dd:c25:c25:dde0:c5fa/1282c19:dd:d9:dd:c25:c25:dde0:c5fa
2522c19:dd:d9:dd:c25:c25:dde0:c5fb/1282c19:dd:d9:dd:c25:c25:dde0:c5fb
2532c19:dd:d9:dd:c25:c25:dde0:c5fc/1282c19:dd:d9:dd:c25:c25:dde0:c5fc
2542c19:dd:d9:dd:c25:c25:dde0:c5fd/1282c19:dd:d9:dd:c25:c25:dde0:c5fd
2552c19:dd:d9:dd:c25:c25:dde0:c5fe/1282c19:dd:d9:dd:c25:c25:dde0:c5fe
2562c19:dd:d9:dd:c25:c25:dde0:c5ff/1282c19:dd:d9:dd:c25:c25:dde0:c5ff

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.