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:ec00:c25:c25e:dd:dddb:2500/120
First address
2c19:dd:ec00:c25:c25e:dd:dddb:2500
Last address
2c19:dd:ec00:c25:c25e:dd:dddb:25ff
Addresses
256
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:ec00:0c25:c25e:00dd:dddb:2500
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
5.2.b.d.d.d.d.d.0.0.e.5.2.c.5.2.c.0.0.0.c.e.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:ec00:c25:c25e:dd:dddb:2500/120 makes 256 subnets of /128.

Subnets
#SubnetLast address
12c19:dd:ec00:c25:c25e:dd:dddb:2500/1282c19:dd:ec00:c25:c25e:dd:dddb:2500
22c19:dd:ec00:c25:c25e:dd:dddb:2501/1282c19:dd:ec00:c25:c25e:dd:dddb:2501
32c19:dd:ec00:c25:c25e:dd:dddb:2502/1282c19:dd:ec00:c25:c25e:dd:dddb:2502
42c19:dd:ec00:c25:c25e:dd:dddb:2503/1282c19:dd:ec00:c25:c25e:dd:dddb:2503
52c19:dd:ec00:c25:c25e:dd:dddb:2504/1282c19:dd:ec00:c25:c25e:dd:dddb:2504
62c19:dd:ec00:c25:c25e:dd:dddb:2505/1282c19:dd:ec00:c25:c25e:dd:dddb:2505
72c19:dd:ec00:c25:c25e:dd:dddb:2506/1282c19:dd:ec00:c25:c25e:dd:dddb:2506
82c19:dd:ec00:c25:c25e:dd:dddb:2507/1282c19:dd:ec00:c25:c25e:dd:dddb:2507
92c19:dd:ec00:c25:c25e:dd:dddb:2508/1282c19:dd:ec00:c25:c25e:dd:dddb:2508
102c19:dd:ec00:c25:c25e:dd:dddb:2509/1282c19:dd:ec00:c25:c25e:dd:dddb:2509
112c19:dd:ec00:c25:c25e:dd:dddb:250a/1282c19:dd:ec00:c25:c25e:dd:dddb:250a
122c19:dd:ec00:c25:c25e:dd:dddb:250b/1282c19:dd:ec00:c25:c25e:dd:dddb:250b
132c19:dd:ec00:c25:c25e:dd:dddb:250c/1282c19:dd:ec00:c25:c25e:dd:dddb:250c
142c19:dd:ec00:c25:c25e:dd:dddb:250d/1282c19:dd:ec00:c25:c25e:dd:dddb:250d
152c19:dd:ec00:c25:c25e:dd:dddb:250e/1282c19:dd:ec00:c25:c25e:dd:dddb:250e
162c19:dd:ec00:c25:c25e:dd:dddb:250f/1282c19:dd:ec00:c25:c25e:dd:dddb:250f
172c19:dd:ec00:c25:c25e:dd:dddb:2510/1282c19:dd:ec00:c25:c25e:dd:dddb:2510
182c19:dd:ec00:c25:c25e:dd:dddb:2511/1282c19:dd:ec00:c25:c25e:dd:dddb:2511
192c19:dd:ec00:c25:c25e:dd:dddb:2512/1282c19:dd:ec00:c25:c25e:dd:dddb:2512
202c19:dd:ec00:c25:c25e:dd:dddb:2513/1282c19:dd:ec00:c25:c25e:dd:dddb:2513
212c19:dd:ec00:c25:c25e:dd:dddb:2514/1282c19:dd:ec00:c25:c25e:dd:dddb:2514
222c19:dd:ec00:c25:c25e:dd:dddb:2515/1282c19:dd:ec00:c25:c25e:dd:dddb:2515
232c19:dd:ec00:c25:c25e:dd:dddb:2516/1282c19:dd:ec00:c25:c25e:dd:dddb:2516
242c19:dd:ec00:c25:c25e:dd:dddb:2517/1282c19:dd:ec00:c25:c25e:dd:dddb:2517
252c19:dd:ec00:c25:c25e:dd:dddb:2518/1282c19:dd:ec00:c25:c25e:dd:dddb:2518
262c19:dd:ec00:c25:c25e:dd:dddb:2519/1282c19:dd:ec00:c25:c25e:dd:dddb:2519
272c19:dd:ec00:c25:c25e:dd:dddb:251a/1282c19:dd:ec00:c25:c25e:dd:dddb:251a
282c19:dd:ec00:c25:c25e:dd:dddb:251b/1282c19:dd:ec00:c25:c25e:dd:dddb:251b
292c19:dd:ec00:c25:c25e:dd:dddb:251c/1282c19:dd:ec00:c25:c25e:dd:dddb:251c
302c19:dd:ec00:c25:c25e:dd:dddb:251d/1282c19:dd:ec00:c25:c25e:dd:dddb:251d
312c19:dd:ec00:c25:c25e:dd:dddb:251e/1282c19:dd:ec00:c25:c25e:dd:dddb:251e
322c19:dd:ec00:c25:c25e:dd:dddb:251f/1282c19:dd:ec00:c25:c25e:dd:dddb:251f
332c19:dd:ec00:c25:c25e:dd:dddb:2520/1282c19:dd:ec00:c25:c25e:dd:dddb:2520
342c19:dd:ec00:c25:c25e:dd:dddb:2521/1282c19:dd:ec00:c25:c25e:dd:dddb:2521
352c19:dd:ec00:c25:c25e:dd:dddb:2522/1282c19:dd:ec00:c25:c25e:dd:dddb:2522
362c19:dd:ec00:c25:c25e:dd:dddb:2523/1282c19:dd:ec00:c25:c25e:dd:dddb:2523
372c19:dd:ec00:c25:c25e:dd:dddb:2524/1282c19:dd:ec00:c25:c25e:dd:dddb:2524
382c19:dd:ec00:c25:c25e:dd:dddb:2525/1282c19:dd:ec00:c25:c25e:dd:dddb:2525
392c19:dd:ec00:c25:c25e:dd:dddb:2526/1282c19:dd:ec00:c25:c25e:dd:dddb:2526
402c19:dd:ec00:c25:c25e:dd:dddb:2527/1282c19:dd:ec00:c25:c25e:dd:dddb:2527
412c19:dd:ec00:c25:c25e:dd:dddb:2528/1282c19:dd:ec00:c25:c25e:dd:dddb:2528
422c19:dd:ec00:c25:c25e:dd:dddb:2529/1282c19:dd:ec00:c25:c25e:dd:dddb:2529
432c19:dd:ec00:c25:c25e:dd:dddb:252a/1282c19:dd:ec00:c25:c25e:dd:dddb:252a
442c19:dd:ec00:c25:c25e:dd:dddb:252b/1282c19:dd:ec00:c25:c25e:dd:dddb:252b
452c19:dd:ec00:c25:c25e:dd:dddb:252c/1282c19:dd:ec00:c25:c25e:dd:dddb:252c
462c19:dd:ec00:c25:c25e:dd:dddb:252d/1282c19:dd:ec00:c25:c25e:dd:dddb:252d
472c19:dd:ec00:c25:c25e:dd:dddb:252e/1282c19:dd:ec00:c25:c25e:dd:dddb:252e
482c19:dd:ec00:c25:c25e:dd:dddb:252f/1282c19:dd:ec00:c25:c25e:dd:dddb:252f
492c19:dd:ec00:c25:c25e:dd:dddb:2530/1282c19:dd:ec00:c25:c25e:dd:dddb:2530
502c19:dd:ec00:c25:c25e:dd:dddb:2531/1282c19:dd:ec00:c25:c25e:dd:dddb:2531
512c19:dd:ec00:c25:c25e:dd:dddb:2532/1282c19:dd:ec00:c25:c25e:dd:dddb:2532
522c19:dd:ec00:c25:c25e:dd:dddb:2533/1282c19:dd:ec00:c25:c25e:dd:dddb:2533
532c19:dd:ec00:c25:c25e:dd:dddb:2534/1282c19:dd:ec00:c25:c25e:dd:dddb:2534
542c19:dd:ec00:c25:c25e:dd:dddb:2535/1282c19:dd:ec00:c25:c25e:dd:dddb:2535
552c19:dd:ec00:c25:c25e:dd:dddb:2536/1282c19:dd:ec00:c25:c25e:dd:dddb:2536
562c19:dd:ec00:c25:c25e:dd:dddb:2537/1282c19:dd:ec00:c25:c25e:dd:dddb:2537
572c19:dd:ec00:c25:c25e:dd:dddb:2538/1282c19:dd:ec00:c25:c25e:dd:dddb:2538
582c19:dd:ec00:c25:c25e:dd:dddb:2539/1282c19:dd:ec00:c25:c25e:dd:dddb:2539
592c19:dd:ec00:c25:c25e:dd:dddb:253a/1282c19:dd:ec00:c25:c25e:dd:dddb:253a
602c19:dd:ec00:c25:c25e:dd:dddb:253b/1282c19:dd:ec00:c25:c25e:dd:dddb:253b
612c19:dd:ec00:c25:c25e:dd:dddb:253c/1282c19:dd:ec00:c25:c25e:dd:dddb:253c
622c19:dd:ec00:c25:c25e:dd:dddb:253d/1282c19:dd:ec00:c25:c25e:dd:dddb:253d
632c19:dd:ec00:c25:c25e:dd:dddb:253e/1282c19:dd:ec00:c25:c25e:dd:dddb:253e
642c19:dd:ec00:c25:c25e:dd:dddb:253f/1282c19:dd:ec00:c25:c25e:dd:dddb:253f
652c19:dd:ec00:c25:c25e:dd:dddb:2540/1282c19:dd:ec00:c25:c25e:dd:dddb:2540
662c19:dd:ec00:c25:c25e:dd:dddb:2541/1282c19:dd:ec00:c25:c25e:dd:dddb:2541
672c19:dd:ec00:c25:c25e:dd:dddb:2542/1282c19:dd:ec00:c25:c25e:dd:dddb:2542
682c19:dd:ec00:c25:c25e:dd:dddb:2543/1282c19:dd:ec00:c25:c25e:dd:dddb:2543
692c19:dd:ec00:c25:c25e:dd:dddb:2544/1282c19:dd:ec00:c25:c25e:dd:dddb:2544
702c19:dd:ec00:c25:c25e:dd:dddb:2545/1282c19:dd:ec00:c25:c25e:dd:dddb:2545
712c19:dd:ec00:c25:c25e:dd:dddb:2546/1282c19:dd:ec00:c25:c25e:dd:dddb:2546
722c19:dd:ec00:c25:c25e:dd:dddb:2547/1282c19:dd:ec00:c25:c25e:dd:dddb:2547
732c19:dd:ec00:c25:c25e:dd:dddb:2548/1282c19:dd:ec00:c25:c25e:dd:dddb:2548
742c19:dd:ec00:c25:c25e:dd:dddb:2549/1282c19:dd:ec00:c25:c25e:dd:dddb:2549
752c19:dd:ec00:c25:c25e:dd:dddb:254a/1282c19:dd:ec00:c25:c25e:dd:dddb:254a
762c19:dd:ec00:c25:c25e:dd:dddb:254b/1282c19:dd:ec00:c25:c25e:dd:dddb:254b
772c19:dd:ec00:c25:c25e:dd:dddb:254c/1282c19:dd:ec00:c25:c25e:dd:dddb:254c
782c19:dd:ec00:c25:c25e:dd:dddb:254d/1282c19:dd:ec00:c25:c25e:dd:dddb:254d
792c19:dd:ec00:c25:c25e:dd:dddb:254e/1282c19:dd:ec00:c25:c25e:dd:dddb:254e
802c19:dd:ec00:c25:c25e:dd:dddb:254f/1282c19:dd:ec00:c25:c25e:dd:dddb:254f
812c19:dd:ec00:c25:c25e:dd:dddb:2550/1282c19:dd:ec00:c25:c25e:dd:dddb:2550
822c19:dd:ec00:c25:c25e:dd:dddb:2551/1282c19:dd:ec00:c25:c25e:dd:dddb:2551
832c19:dd:ec00:c25:c25e:dd:dddb:2552/1282c19:dd:ec00:c25:c25e:dd:dddb:2552
842c19:dd:ec00:c25:c25e:dd:dddb:2553/1282c19:dd:ec00:c25:c25e:dd:dddb:2553
852c19:dd:ec00:c25:c25e:dd:dddb:2554/1282c19:dd:ec00:c25:c25e:dd:dddb:2554
862c19:dd:ec00:c25:c25e:dd:dddb:2555/1282c19:dd:ec00:c25:c25e:dd:dddb:2555
872c19:dd:ec00:c25:c25e:dd:dddb:2556/1282c19:dd:ec00:c25:c25e:dd:dddb:2556
882c19:dd:ec00:c25:c25e:dd:dddb:2557/1282c19:dd:ec00:c25:c25e:dd:dddb:2557
892c19:dd:ec00:c25:c25e:dd:dddb:2558/1282c19:dd:ec00:c25:c25e:dd:dddb:2558
902c19:dd:ec00:c25:c25e:dd:dddb:2559/1282c19:dd:ec00:c25:c25e:dd:dddb:2559
912c19:dd:ec00:c25:c25e:dd:dddb:255a/1282c19:dd:ec00:c25:c25e:dd:dddb:255a
922c19:dd:ec00:c25:c25e:dd:dddb:255b/1282c19:dd:ec00:c25:c25e:dd:dddb:255b
932c19:dd:ec00:c25:c25e:dd:dddb:255c/1282c19:dd:ec00:c25:c25e:dd:dddb:255c
942c19:dd:ec00:c25:c25e:dd:dddb:255d/1282c19:dd:ec00:c25:c25e:dd:dddb:255d
952c19:dd:ec00:c25:c25e:dd:dddb:255e/1282c19:dd:ec00:c25:c25e:dd:dddb:255e
962c19:dd:ec00:c25:c25e:dd:dddb:255f/1282c19:dd:ec00:c25:c25e:dd:dddb:255f
972c19:dd:ec00:c25:c25e:dd:dddb:2560/1282c19:dd:ec00:c25:c25e:dd:dddb:2560
982c19:dd:ec00:c25:c25e:dd:dddb:2561/1282c19:dd:ec00:c25:c25e:dd:dddb:2561
992c19:dd:ec00:c25:c25e:dd:dddb:2562/1282c19:dd:ec00:c25:c25e:dd:dddb:2562
1002c19:dd:ec00:c25:c25e:dd:dddb:2563/1282c19:dd:ec00:c25:c25e:dd:dddb:2563
1012c19:dd:ec00:c25:c25e:dd:dddb:2564/1282c19:dd:ec00:c25:c25e:dd:dddb:2564
1022c19:dd:ec00:c25:c25e:dd:dddb:2565/1282c19:dd:ec00:c25:c25e:dd:dddb:2565
1032c19:dd:ec00:c25:c25e:dd:dddb:2566/1282c19:dd:ec00:c25:c25e:dd:dddb:2566
1042c19:dd:ec00:c25:c25e:dd:dddb:2567/1282c19:dd:ec00:c25:c25e:dd:dddb:2567
1052c19:dd:ec00:c25:c25e:dd:dddb:2568/1282c19:dd:ec00:c25:c25e:dd:dddb:2568
1062c19:dd:ec00:c25:c25e:dd:dddb:2569/1282c19:dd:ec00:c25:c25e:dd:dddb:2569
1072c19:dd:ec00:c25:c25e:dd:dddb:256a/1282c19:dd:ec00:c25:c25e:dd:dddb:256a
1082c19:dd:ec00:c25:c25e:dd:dddb:256b/1282c19:dd:ec00:c25:c25e:dd:dddb:256b
1092c19:dd:ec00:c25:c25e:dd:dddb:256c/1282c19:dd:ec00:c25:c25e:dd:dddb:256c
1102c19:dd:ec00:c25:c25e:dd:dddb:256d/1282c19:dd:ec00:c25:c25e:dd:dddb:256d
1112c19:dd:ec00:c25:c25e:dd:dddb:256e/1282c19:dd:ec00:c25:c25e:dd:dddb:256e
1122c19:dd:ec00:c25:c25e:dd:dddb:256f/1282c19:dd:ec00:c25:c25e:dd:dddb:256f
1132c19:dd:ec00:c25:c25e:dd:dddb:2570/1282c19:dd:ec00:c25:c25e:dd:dddb:2570
1142c19:dd:ec00:c25:c25e:dd:dddb:2571/1282c19:dd:ec00:c25:c25e:dd:dddb:2571
1152c19:dd:ec00:c25:c25e:dd:dddb:2572/1282c19:dd:ec00:c25:c25e:dd:dddb:2572
1162c19:dd:ec00:c25:c25e:dd:dddb:2573/1282c19:dd:ec00:c25:c25e:dd:dddb:2573
1172c19:dd:ec00:c25:c25e:dd:dddb:2574/1282c19:dd:ec00:c25:c25e:dd:dddb:2574
1182c19:dd:ec00:c25:c25e:dd:dddb:2575/1282c19:dd:ec00:c25:c25e:dd:dddb:2575
1192c19:dd:ec00:c25:c25e:dd:dddb:2576/1282c19:dd:ec00:c25:c25e:dd:dddb:2576
1202c19:dd:ec00:c25:c25e:dd:dddb:2577/1282c19:dd:ec00:c25:c25e:dd:dddb:2577
1212c19:dd:ec00:c25:c25e:dd:dddb:2578/1282c19:dd:ec00:c25:c25e:dd:dddb:2578
1222c19:dd:ec00:c25:c25e:dd:dddb:2579/1282c19:dd:ec00:c25:c25e:dd:dddb:2579
1232c19:dd:ec00:c25:c25e:dd:dddb:257a/1282c19:dd:ec00:c25:c25e:dd:dddb:257a
1242c19:dd:ec00:c25:c25e:dd:dddb:257b/1282c19:dd:ec00:c25:c25e:dd:dddb:257b
1252c19:dd:ec00:c25:c25e:dd:dddb:257c/1282c19:dd:ec00:c25:c25e:dd:dddb:257c
1262c19:dd:ec00:c25:c25e:dd:dddb:257d/1282c19:dd:ec00:c25:c25e:dd:dddb:257d
1272c19:dd:ec00:c25:c25e:dd:dddb:257e/1282c19:dd:ec00:c25:c25e:dd:dddb:257e
1282c19:dd:ec00:c25:c25e:dd:dddb:257f/1282c19:dd:ec00:c25:c25e:dd:dddb:257f
1292c19:dd:ec00:c25:c25e:dd:dddb:2580/1282c19:dd:ec00:c25:c25e:dd:dddb:2580
1302c19:dd:ec00:c25:c25e:dd:dddb:2581/1282c19:dd:ec00:c25:c25e:dd:dddb:2581
1312c19:dd:ec00:c25:c25e:dd:dddb:2582/1282c19:dd:ec00:c25:c25e:dd:dddb:2582
1322c19:dd:ec00:c25:c25e:dd:dddb:2583/1282c19:dd:ec00:c25:c25e:dd:dddb:2583
1332c19:dd:ec00:c25:c25e:dd:dddb:2584/1282c19:dd:ec00:c25:c25e:dd:dddb:2584
1342c19:dd:ec00:c25:c25e:dd:dddb:2585/1282c19:dd:ec00:c25:c25e:dd:dddb:2585
1352c19:dd:ec00:c25:c25e:dd:dddb:2586/1282c19:dd:ec00:c25:c25e:dd:dddb:2586
1362c19:dd:ec00:c25:c25e:dd:dddb:2587/1282c19:dd:ec00:c25:c25e:dd:dddb:2587
1372c19:dd:ec00:c25:c25e:dd:dddb:2588/1282c19:dd:ec00:c25:c25e:dd:dddb:2588
1382c19:dd:ec00:c25:c25e:dd:dddb:2589/1282c19:dd:ec00:c25:c25e:dd:dddb:2589
1392c19:dd:ec00:c25:c25e:dd:dddb:258a/1282c19:dd:ec00:c25:c25e:dd:dddb:258a
1402c19:dd:ec00:c25:c25e:dd:dddb:258b/1282c19:dd:ec00:c25:c25e:dd:dddb:258b
1412c19:dd:ec00:c25:c25e:dd:dddb:258c/1282c19:dd:ec00:c25:c25e:dd:dddb:258c
1422c19:dd:ec00:c25:c25e:dd:dddb:258d/1282c19:dd:ec00:c25:c25e:dd:dddb:258d
1432c19:dd:ec00:c25:c25e:dd:dddb:258e/1282c19:dd:ec00:c25:c25e:dd:dddb:258e
1442c19:dd:ec00:c25:c25e:dd:dddb:258f/1282c19:dd:ec00:c25:c25e:dd:dddb:258f
1452c19:dd:ec00:c25:c25e:dd:dddb:2590/1282c19:dd:ec00:c25:c25e:dd:dddb:2590
1462c19:dd:ec00:c25:c25e:dd:dddb:2591/1282c19:dd:ec00:c25:c25e:dd:dddb:2591
1472c19:dd:ec00:c25:c25e:dd:dddb:2592/1282c19:dd:ec00:c25:c25e:dd:dddb:2592
1482c19:dd:ec00:c25:c25e:dd:dddb:2593/1282c19:dd:ec00:c25:c25e:dd:dddb:2593
1492c19:dd:ec00:c25:c25e:dd:dddb:2594/1282c19:dd:ec00:c25:c25e:dd:dddb:2594
1502c19:dd:ec00:c25:c25e:dd:dddb:2595/1282c19:dd:ec00:c25:c25e:dd:dddb:2595
1512c19:dd:ec00:c25:c25e:dd:dddb:2596/1282c19:dd:ec00:c25:c25e:dd:dddb:2596
1522c19:dd:ec00:c25:c25e:dd:dddb:2597/1282c19:dd:ec00:c25:c25e:dd:dddb:2597
1532c19:dd:ec00:c25:c25e:dd:dddb:2598/1282c19:dd:ec00:c25:c25e:dd:dddb:2598
1542c19:dd:ec00:c25:c25e:dd:dddb:2599/1282c19:dd:ec00:c25:c25e:dd:dddb:2599
1552c19:dd:ec00:c25:c25e:dd:dddb:259a/1282c19:dd:ec00:c25:c25e:dd:dddb:259a
1562c19:dd:ec00:c25:c25e:dd:dddb:259b/1282c19:dd:ec00:c25:c25e:dd:dddb:259b
1572c19:dd:ec00:c25:c25e:dd:dddb:259c/1282c19:dd:ec00:c25:c25e:dd:dddb:259c
1582c19:dd:ec00:c25:c25e:dd:dddb:259d/1282c19:dd:ec00:c25:c25e:dd:dddb:259d
1592c19:dd:ec00:c25:c25e:dd:dddb:259e/1282c19:dd:ec00:c25:c25e:dd:dddb:259e
1602c19:dd:ec00:c25:c25e:dd:dddb:259f/1282c19:dd:ec00:c25:c25e:dd:dddb:259f
1612c19:dd:ec00:c25:c25e:dd:dddb:25a0/1282c19:dd:ec00:c25:c25e:dd:dddb:25a0
1622c19:dd:ec00:c25:c25e:dd:dddb:25a1/1282c19:dd:ec00:c25:c25e:dd:dddb:25a1
1632c19:dd:ec00:c25:c25e:dd:dddb:25a2/1282c19:dd:ec00:c25:c25e:dd:dddb:25a2
1642c19:dd:ec00:c25:c25e:dd:dddb:25a3/1282c19:dd:ec00:c25:c25e:dd:dddb:25a3
1652c19:dd:ec00:c25:c25e:dd:dddb:25a4/1282c19:dd:ec00:c25:c25e:dd:dddb:25a4
1662c19:dd:ec00:c25:c25e:dd:dddb:25a5/1282c19:dd:ec00:c25:c25e:dd:dddb:25a5
1672c19:dd:ec00:c25:c25e:dd:dddb:25a6/1282c19:dd:ec00:c25:c25e:dd:dddb:25a6
1682c19:dd:ec00:c25:c25e:dd:dddb:25a7/1282c19:dd:ec00:c25:c25e:dd:dddb:25a7
1692c19:dd:ec00:c25:c25e:dd:dddb:25a8/1282c19:dd:ec00:c25:c25e:dd:dddb:25a8
1702c19:dd:ec00:c25:c25e:dd:dddb:25a9/1282c19:dd:ec00:c25:c25e:dd:dddb:25a9
1712c19:dd:ec00:c25:c25e:dd:dddb:25aa/1282c19:dd:ec00:c25:c25e:dd:dddb:25aa
1722c19:dd:ec00:c25:c25e:dd:dddb:25ab/1282c19:dd:ec00:c25:c25e:dd:dddb:25ab
1732c19:dd:ec00:c25:c25e:dd:dddb:25ac/1282c19:dd:ec00:c25:c25e:dd:dddb:25ac
1742c19:dd:ec00:c25:c25e:dd:dddb:25ad/1282c19:dd:ec00:c25:c25e:dd:dddb:25ad
1752c19:dd:ec00:c25:c25e:dd:dddb:25ae/1282c19:dd:ec00:c25:c25e:dd:dddb:25ae
1762c19:dd:ec00:c25:c25e:dd:dddb:25af/1282c19:dd:ec00:c25:c25e:dd:dddb:25af
1772c19:dd:ec00:c25:c25e:dd:dddb:25b0/1282c19:dd:ec00:c25:c25e:dd:dddb:25b0
1782c19:dd:ec00:c25:c25e:dd:dddb:25b1/1282c19:dd:ec00:c25:c25e:dd:dddb:25b1
1792c19:dd:ec00:c25:c25e:dd:dddb:25b2/1282c19:dd:ec00:c25:c25e:dd:dddb:25b2
1802c19:dd:ec00:c25:c25e:dd:dddb:25b3/1282c19:dd:ec00:c25:c25e:dd:dddb:25b3
1812c19:dd:ec00:c25:c25e:dd:dddb:25b4/1282c19:dd:ec00:c25:c25e:dd:dddb:25b4
1822c19:dd:ec00:c25:c25e:dd:dddb:25b5/1282c19:dd:ec00:c25:c25e:dd:dddb:25b5
1832c19:dd:ec00:c25:c25e:dd:dddb:25b6/1282c19:dd:ec00:c25:c25e:dd:dddb:25b6
1842c19:dd:ec00:c25:c25e:dd:dddb:25b7/1282c19:dd:ec00:c25:c25e:dd:dddb:25b7
1852c19:dd:ec00:c25:c25e:dd:dddb:25b8/1282c19:dd:ec00:c25:c25e:dd:dddb:25b8
1862c19:dd:ec00:c25:c25e:dd:dddb:25b9/1282c19:dd:ec00:c25:c25e:dd:dddb:25b9
1872c19:dd:ec00:c25:c25e:dd:dddb:25ba/1282c19:dd:ec00:c25:c25e:dd:dddb:25ba
1882c19:dd:ec00:c25:c25e:dd:dddb:25bb/1282c19:dd:ec00:c25:c25e:dd:dddb:25bb
1892c19:dd:ec00:c25:c25e:dd:dddb:25bc/1282c19:dd:ec00:c25:c25e:dd:dddb:25bc
1902c19:dd:ec00:c25:c25e:dd:dddb:25bd/1282c19:dd:ec00:c25:c25e:dd:dddb:25bd
1912c19:dd:ec00:c25:c25e:dd:dddb:25be/1282c19:dd:ec00:c25:c25e:dd:dddb:25be
1922c19:dd:ec00:c25:c25e:dd:dddb:25bf/1282c19:dd:ec00:c25:c25e:dd:dddb:25bf
1932c19:dd:ec00:c25:c25e:dd:dddb:25c0/1282c19:dd:ec00:c25:c25e:dd:dddb:25c0
1942c19:dd:ec00:c25:c25e:dd:dddb:25c1/1282c19:dd:ec00:c25:c25e:dd:dddb:25c1
1952c19:dd:ec00:c25:c25e:dd:dddb:25c2/1282c19:dd:ec00:c25:c25e:dd:dddb:25c2
1962c19:dd:ec00:c25:c25e:dd:dddb:25c3/1282c19:dd:ec00:c25:c25e:dd:dddb:25c3
1972c19:dd:ec00:c25:c25e:dd:dddb:25c4/1282c19:dd:ec00:c25:c25e:dd:dddb:25c4
1982c19:dd:ec00:c25:c25e:dd:dddb:25c5/1282c19:dd:ec00:c25:c25e:dd:dddb:25c5
1992c19:dd:ec00:c25:c25e:dd:dddb:25c6/1282c19:dd:ec00:c25:c25e:dd:dddb:25c6
2002c19:dd:ec00:c25:c25e:dd:dddb:25c7/1282c19:dd:ec00:c25:c25e:dd:dddb:25c7
2012c19:dd:ec00:c25:c25e:dd:dddb:25c8/1282c19:dd:ec00:c25:c25e:dd:dddb:25c8
2022c19:dd:ec00:c25:c25e:dd:dddb:25c9/1282c19:dd:ec00:c25:c25e:dd:dddb:25c9
2032c19:dd:ec00:c25:c25e:dd:dddb:25ca/1282c19:dd:ec00:c25:c25e:dd:dddb:25ca
2042c19:dd:ec00:c25:c25e:dd:dddb:25cb/1282c19:dd:ec00:c25:c25e:dd:dddb:25cb
2052c19:dd:ec00:c25:c25e:dd:dddb:25cc/1282c19:dd:ec00:c25:c25e:dd:dddb:25cc
2062c19:dd:ec00:c25:c25e:dd:dddb:25cd/1282c19:dd:ec00:c25:c25e:dd:dddb:25cd
2072c19:dd:ec00:c25:c25e:dd:dddb:25ce/1282c19:dd:ec00:c25:c25e:dd:dddb:25ce
2082c19:dd:ec00:c25:c25e:dd:dddb:25cf/1282c19:dd:ec00:c25:c25e:dd:dddb:25cf
2092c19:dd:ec00:c25:c25e:dd:dddb:25d0/1282c19:dd:ec00:c25:c25e:dd:dddb:25d0
2102c19:dd:ec00:c25:c25e:dd:dddb:25d1/1282c19:dd:ec00:c25:c25e:dd:dddb:25d1
2112c19:dd:ec00:c25:c25e:dd:dddb:25d2/1282c19:dd:ec00:c25:c25e:dd:dddb:25d2
2122c19:dd:ec00:c25:c25e:dd:dddb:25d3/1282c19:dd:ec00:c25:c25e:dd:dddb:25d3
2132c19:dd:ec00:c25:c25e:dd:dddb:25d4/1282c19:dd:ec00:c25:c25e:dd:dddb:25d4
2142c19:dd:ec00:c25:c25e:dd:dddb:25d5/1282c19:dd:ec00:c25:c25e:dd:dddb:25d5
2152c19:dd:ec00:c25:c25e:dd:dddb:25d6/1282c19:dd:ec00:c25:c25e:dd:dddb:25d6
2162c19:dd:ec00:c25:c25e:dd:dddb:25d7/1282c19:dd:ec00:c25:c25e:dd:dddb:25d7
2172c19:dd:ec00:c25:c25e:dd:dddb:25d8/1282c19:dd:ec00:c25:c25e:dd:dddb:25d8
2182c19:dd:ec00:c25:c25e:dd:dddb:25d9/1282c19:dd:ec00:c25:c25e:dd:dddb:25d9
2192c19:dd:ec00:c25:c25e:dd:dddb:25da/1282c19:dd:ec00:c25:c25e:dd:dddb:25da
2202c19:dd:ec00:c25:c25e:dd:dddb:25db/1282c19:dd:ec00:c25:c25e:dd:dddb:25db
2212c19:dd:ec00:c25:c25e:dd:dddb:25dc/1282c19:dd:ec00:c25:c25e:dd:dddb:25dc
2222c19:dd:ec00:c25:c25e:dd:dddb:25dd/1282c19:dd:ec00:c25:c25e:dd:dddb:25dd
2232c19:dd:ec00:c25:c25e:dd:dddb:25de/1282c19:dd:ec00:c25:c25e:dd:dddb:25de
2242c19:dd:ec00:c25:c25e:dd:dddb:25df/1282c19:dd:ec00:c25:c25e:dd:dddb:25df
2252c19:dd:ec00:c25:c25e:dd:dddb:25e0/1282c19:dd:ec00:c25:c25e:dd:dddb:25e0
2262c19:dd:ec00:c25:c25e:dd:dddb:25e1/1282c19:dd:ec00:c25:c25e:dd:dddb:25e1
2272c19:dd:ec00:c25:c25e:dd:dddb:25e2/1282c19:dd:ec00:c25:c25e:dd:dddb:25e2
2282c19:dd:ec00:c25:c25e:dd:dddb:25e3/1282c19:dd:ec00:c25:c25e:dd:dddb:25e3
2292c19:dd:ec00:c25:c25e:dd:dddb:25e4/1282c19:dd:ec00:c25:c25e:dd:dddb:25e4
2302c19:dd:ec00:c25:c25e:dd:dddb:25e5/1282c19:dd:ec00:c25:c25e:dd:dddb:25e5
2312c19:dd:ec00:c25:c25e:dd:dddb:25e6/1282c19:dd:ec00:c25:c25e:dd:dddb:25e6
2322c19:dd:ec00:c25:c25e:dd:dddb:25e7/1282c19:dd:ec00:c25:c25e:dd:dddb:25e7
2332c19:dd:ec00:c25:c25e:dd:dddb:25e8/1282c19:dd:ec00:c25:c25e:dd:dddb:25e8
2342c19:dd:ec00:c25:c25e:dd:dddb:25e9/1282c19:dd:ec00:c25:c25e:dd:dddb:25e9
2352c19:dd:ec00:c25:c25e:dd:dddb:25ea/1282c19:dd:ec00:c25:c25e:dd:dddb:25ea
2362c19:dd:ec00:c25:c25e:dd:dddb:25eb/1282c19:dd:ec00:c25:c25e:dd:dddb:25eb
2372c19:dd:ec00:c25:c25e:dd:dddb:25ec/1282c19:dd:ec00:c25:c25e:dd:dddb:25ec
2382c19:dd:ec00:c25:c25e:dd:dddb:25ed/1282c19:dd:ec00:c25:c25e:dd:dddb:25ed
2392c19:dd:ec00:c25:c25e:dd:dddb:25ee/1282c19:dd:ec00:c25:c25e:dd:dddb:25ee
2402c19:dd:ec00:c25:c25e:dd:dddb:25ef/1282c19:dd:ec00:c25:c25e:dd:dddb:25ef
2412c19:dd:ec00:c25:c25e:dd:dddb:25f0/1282c19:dd:ec00:c25:c25e:dd:dddb:25f0
2422c19:dd:ec00:c25:c25e:dd:dddb:25f1/1282c19:dd:ec00:c25:c25e:dd:dddb:25f1
2432c19:dd:ec00:c25:c25e:dd:dddb:25f2/1282c19:dd:ec00:c25:c25e:dd:dddb:25f2
2442c19:dd:ec00:c25:c25e:dd:dddb:25f3/1282c19:dd:ec00:c25:c25e:dd:dddb:25f3
2452c19:dd:ec00:c25:c25e:dd:dddb:25f4/1282c19:dd:ec00:c25:c25e:dd:dddb:25f4
2462c19:dd:ec00:c25:c25e:dd:dddb:25f5/1282c19:dd:ec00:c25:c25e:dd:dddb:25f5
2472c19:dd:ec00:c25:c25e:dd:dddb:25f6/1282c19:dd:ec00:c25:c25e:dd:dddb:25f6
2482c19:dd:ec00:c25:c25e:dd:dddb:25f7/1282c19:dd:ec00:c25:c25e:dd:dddb:25f7
2492c19:dd:ec00:c25:c25e:dd:dddb:25f8/1282c19:dd:ec00:c25:c25e:dd:dddb:25f8
2502c19:dd:ec00:c25:c25e:dd:dddb:25f9/1282c19:dd:ec00:c25:c25e:dd:dddb:25f9
2512c19:dd:ec00:c25:c25e:dd:dddb:25fa/1282c19:dd:ec00:c25:c25e:dd:dddb:25fa
2522c19:dd:ec00:c25:c25e:dd:dddb:25fb/1282c19:dd:ec00:c25:c25e:dd:dddb:25fb
2532c19:dd:ec00:c25:c25e:dd:dddb:25fc/1282c19:dd:ec00:c25:c25e:dd:dddb:25fc
2542c19:dd:ec00:c25:c25e:dd:dddb:25fd/1282c19:dd:ec00:c25:c25e:dd:dddb:25fd
2552c19:dd:ec00:c25:c25e:dd:dddb:25fe/1282c19:dd:ec00:c25:c25e:dd:dddb:25fe
2562c19:dd:ec00:c25:c25e:dd:dddb:25ff/1282c19:dd:ec00:c25:c25e:dd:dddb:25ff

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.