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/116
Addresses4,096
/64 networksPart of one
Network
2c19:dd:d9:dd:c25:c25:600a:1000/116
First address
2c19:dd:d9:dd:c25:c25:600a:1000
Last address
2c19:dd:d9:dd:c25:c25:600a:1fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:600a:1000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
1.a.0.0.6.5.2.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/124
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2c19:dd:d9:dd:c25:c25:600a:1000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:600a:1000/1242c19:dd:d9:dd:c25:c25:600a:100f
22c19:dd:d9:dd:c25:c25:600a:1010/1242c19:dd:d9:dd:c25:c25:600a:101f
32c19:dd:d9:dd:c25:c25:600a:1020/1242c19:dd:d9:dd:c25:c25:600a:102f
42c19:dd:d9:dd:c25:c25:600a:1030/1242c19:dd:d9:dd:c25:c25:600a:103f
52c19:dd:d9:dd:c25:c25:600a:1040/1242c19:dd:d9:dd:c25:c25:600a:104f
62c19:dd:d9:dd:c25:c25:600a:1050/1242c19:dd:d9:dd:c25:c25:600a:105f
72c19:dd:d9:dd:c25:c25:600a:1060/1242c19:dd:d9:dd:c25:c25:600a:106f
82c19:dd:d9:dd:c25:c25:600a:1070/1242c19:dd:d9:dd:c25:c25:600a:107f
92c19:dd:d9:dd:c25:c25:600a:1080/1242c19:dd:d9:dd:c25:c25:600a:108f
102c19:dd:d9:dd:c25:c25:600a:1090/1242c19:dd:d9:dd:c25:c25:600a:109f
112c19:dd:d9:dd:c25:c25:600a:10a0/1242c19:dd:d9:dd:c25:c25:600a:10af
122c19:dd:d9:dd:c25:c25:600a:10b0/1242c19:dd:d9:dd:c25:c25:600a:10bf
132c19:dd:d9:dd:c25:c25:600a:10c0/1242c19:dd:d9:dd:c25:c25:600a:10cf
142c19:dd:d9:dd:c25:c25:600a:10d0/1242c19:dd:d9:dd:c25:c25:600a:10df
152c19:dd:d9:dd:c25:c25:600a:10e0/1242c19:dd:d9:dd:c25:c25:600a:10ef
162c19:dd:d9:dd:c25:c25:600a:10f0/1242c19:dd:d9:dd:c25:c25:600a:10ff
172c19:dd:d9:dd:c25:c25:600a:1100/1242c19:dd:d9:dd:c25:c25:600a:110f
182c19:dd:d9:dd:c25:c25:600a:1110/1242c19:dd:d9:dd:c25:c25:600a:111f
192c19:dd:d9:dd:c25:c25:600a:1120/1242c19:dd:d9:dd:c25:c25:600a:112f
202c19:dd:d9:dd:c25:c25:600a:1130/1242c19:dd:d9:dd:c25:c25:600a:113f
212c19:dd:d9:dd:c25:c25:600a:1140/1242c19:dd:d9:dd:c25:c25:600a:114f
222c19:dd:d9:dd:c25:c25:600a:1150/1242c19:dd:d9:dd:c25:c25:600a:115f
232c19:dd:d9:dd:c25:c25:600a:1160/1242c19:dd:d9:dd:c25:c25:600a:116f
242c19:dd:d9:dd:c25:c25:600a:1170/1242c19:dd:d9:dd:c25:c25:600a:117f
252c19:dd:d9:dd:c25:c25:600a:1180/1242c19:dd:d9:dd:c25:c25:600a:118f
262c19:dd:d9:dd:c25:c25:600a:1190/1242c19:dd:d9:dd:c25:c25:600a:119f
272c19:dd:d9:dd:c25:c25:600a:11a0/1242c19:dd:d9:dd:c25:c25:600a:11af
282c19:dd:d9:dd:c25:c25:600a:11b0/1242c19:dd:d9:dd:c25:c25:600a:11bf
292c19:dd:d9:dd:c25:c25:600a:11c0/1242c19:dd:d9:dd:c25:c25:600a:11cf
302c19:dd:d9:dd:c25:c25:600a:11d0/1242c19:dd:d9:dd:c25:c25:600a:11df
312c19:dd:d9:dd:c25:c25:600a:11e0/1242c19:dd:d9:dd:c25:c25:600a:11ef
322c19:dd:d9:dd:c25:c25:600a:11f0/1242c19:dd:d9:dd:c25:c25:600a:11ff
332c19:dd:d9:dd:c25:c25:600a:1200/1242c19:dd:d9:dd:c25:c25:600a:120f
342c19:dd:d9:dd:c25:c25:600a:1210/1242c19:dd:d9:dd:c25:c25:600a:121f
352c19:dd:d9:dd:c25:c25:600a:1220/1242c19:dd:d9:dd:c25:c25:600a:122f
362c19:dd:d9:dd:c25:c25:600a:1230/1242c19:dd:d9:dd:c25:c25:600a:123f
372c19:dd:d9:dd:c25:c25:600a:1240/1242c19:dd:d9:dd:c25:c25:600a:124f
382c19:dd:d9:dd:c25:c25:600a:1250/1242c19:dd:d9:dd:c25:c25:600a:125f
392c19:dd:d9:dd:c25:c25:600a:1260/1242c19:dd:d9:dd:c25:c25:600a:126f
402c19:dd:d9:dd:c25:c25:600a:1270/1242c19:dd:d9:dd:c25:c25:600a:127f
412c19:dd:d9:dd:c25:c25:600a:1280/1242c19:dd:d9:dd:c25:c25:600a:128f
422c19:dd:d9:dd:c25:c25:600a:1290/1242c19:dd:d9:dd:c25:c25:600a:129f
432c19:dd:d9:dd:c25:c25:600a:12a0/1242c19:dd:d9:dd:c25:c25:600a:12af
442c19:dd:d9:dd:c25:c25:600a:12b0/1242c19:dd:d9:dd:c25:c25:600a:12bf
452c19:dd:d9:dd:c25:c25:600a:12c0/1242c19:dd:d9:dd:c25:c25:600a:12cf
462c19:dd:d9:dd:c25:c25:600a:12d0/1242c19:dd:d9:dd:c25:c25:600a:12df
472c19:dd:d9:dd:c25:c25:600a:12e0/1242c19:dd:d9:dd:c25:c25:600a:12ef
482c19:dd:d9:dd:c25:c25:600a:12f0/1242c19:dd:d9:dd:c25:c25:600a:12ff
492c19:dd:d9:dd:c25:c25:600a:1300/1242c19:dd:d9:dd:c25:c25:600a:130f
502c19:dd:d9:dd:c25:c25:600a:1310/1242c19:dd:d9:dd:c25:c25:600a:131f
512c19:dd:d9:dd:c25:c25:600a:1320/1242c19:dd:d9:dd:c25:c25:600a:132f
522c19:dd:d9:dd:c25:c25:600a:1330/1242c19:dd:d9:dd:c25:c25:600a:133f
532c19:dd:d9:dd:c25:c25:600a:1340/1242c19:dd:d9:dd:c25:c25:600a:134f
542c19:dd:d9:dd:c25:c25:600a:1350/1242c19:dd:d9:dd:c25:c25:600a:135f
552c19:dd:d9:dd:c25:c25:600a:1360/1242c19:dd:d9:dd:c25:c25:600a:136f
562c19:dd:d9:dd:c25:c25:600a:1370/1242c19:dd:d9:dd:c25:c25:600a:137f
572c19:dd:d9:dd:c25:c25:600a:1380/1242c19:dd:d9:dd:c25:c25:600a:138f
582c19:dd:d9:dd:c25:c25:600a:1390/1242c19:dd:d9:dd:c25:c25:600a:139f
592c19:dd:d9:dd:c25:c25:600a:13a0/1242c19:dd:d9:dd:c25:c25:600a:13af
602c19:dd:d9:dd:c25:c25:600a:13b0/1242c19:dd:d9:dd:c25:c25:600a:13bf
612c19:dd:d9:dd:c25:c25:600a:13c0/1242c19:dd:d9:dd:c25:c25:600a:13cf
622c19:dd:d9:dd:c25:c25:600a:13d0/1242c19:dd:d9:dd:c25:c25:600a:13df
632c19:dd:d9:dd:c25:c25:600a:13e0/1242c19:dd:d9:dd:c25:c25:600a:13ef
642c19:dd:d9:dd:c25:c25:600a:13f0/1242c19:dd:d9:dd:c25:c25:600a:13ff
652c19:dd:d9:dd:c25:c25:600a:1400/1242c19:dd:d9:dd:c25:c25:600a:140f
662c19:dd:d9:dd:c25:c25:600a:1410/1242c19:dd:d9:dd:c25:c25:600a:141f
672c19:dd:d9:dd:c25:c25:600a:1420/1242c19:dd:d9:dd:c25:c25:600a:142f
682c19:dd:d9:dd:c25:c25:600a:1430/1242c19:dd:d9:dd:c25:c25:600a:143f
692c19:dd:d9:dd:c25:c25:600a:1440/1242c19:dd:d9:dd:c25:c25:600a:144f
702c19:dd:d9:dd:c25:c25:600a:1450/1242c19:dd:d9:dd:c25:c25:600a:145f
712c19:dd:d9:dd:c25:c25:600a:1460/1242c19:dd:d9:dd:c25:c25:600a:146f
722c19:dd:d9:dd:c25:c25:600a:1470/1242c19:dd:d9:dd:c25:c25:600a:147f
732c19:dd:d9:dd:c25:c25:600a:1480/1242c19:dd:d9:dd:c25:c25:600a:148f
742c19:dd:d9:dd:c25:c25:600a:1490/1242c19:dd:d9:dd:c25:c25:600a:149f
752c19:dd:d9:dd:c25:c25:600a:14a0/1242c19:dd:d9:dd:c25:c25:600a:14af
762c19:dd:d9:dd:c25:c25:600a:14b0/1242c19:dd:d9:dd:c25:c25:600a:14bf
772c19:dd:d9:dd:c25:c25:600a:14c0/1242c19:dd:d9:dd:c25:c25:600a:14cf
782c19:dd:d9:dd:c25:c25:600a:14d0/1242c19:dd:d9:dd:c25:c25:600a:14df
792c19:dd:d9:dd:c25:c25:600a:14e0/1242c19:dd:d9:dd:c25:c25:600a:14ef
802c19:dd:d9:dd:c25:c25:600a:14f0/1242c19:dd:d9:dd:c25:c25:600a:14ff
812c19:dd:d9:dd:c25:c25:600a:1500/1242c19:dd:d9:dd:c25:c25:600a:150f
822c19:dd:d9:dd:c25:c25:600a:1510/1242c19:dd:d9:dd:c25:c25:600a:151f
832c19:dd:d9:dd:c25:c25:600a:1520/1242c19:dd:d9:dd:c25:c25:600a:152f
842c19:dd:d9:dd:c25:c25:600a:1530/1242c19:dd:d9:dd:c25:c25:600a:153f
852c19:dd:d9:dd:c25:c25:600a:1540/1242c19:dd:d9:dd:c25:c25:600a:154f
862c19:dd:d9:dd:c25:c25:600a:1550/1242c19:dd:d9:dd:c25:c25:600a:155f
872c19:dd:d9:dd:c25:c25:600a:1560/1242c19:dd:d9:dd:c25:c25:600a:156f
882c19:dd:d9:dd:c25:c25:600a:1570/1242c19:dd:d9:dd:c25:c25:600a:157f
892c19:dd:d9:dd:c25:c25:600a:1580/1242c19:dd:d9:dd:c25:c25:600a:158f
902c19:dd:d9:dd:c25:c25:600a:1590/1242c19:dd:d9:dd:c25:c25:600a:159f
912c19:dd:d9:dd:c25:c25:600a:15a0/1242c19:dd:d9:dd:c25:c25:600a:15af
922c19:dd:d9:dd:c25:c25:600a:15b0/1242c19:dd:d9:dd:c25:c25:600a:15bf
932c19:dd:d9:dd:c25:c25:600a:15c0/1242c19:dd:d9:dd:c25:c25:600a:15cf
942c19:dd:d9:dd:c25:c25:600a:15d0/1242c19:dd:d9:dd:c25:c25:600a:15df
952c19:dd:d9:dd:c25:c25:600a:15e0/1242c19:dd:d9:dd:c25:c25:600a:15ef
962c19:dd:d9:dd:c25:c25:600a:15f0/1242c19:dd:d9:dd:c25:c25:600a:15ff
972c19:dd:d9:dd:c25:c25:600a:1600/1242c19:dd:d9:dd:c25:c25:600a:160f
982c19:dd:d9:dd:c25:c25:600a:1610/1242c19:dd:d9:dd:c25:c25:600a:161f
992c19:dd:d9:dd:c25:c25:600a:1620/1242c19:dd:d9:dd:c25:c25:600a:162f
1002c19:dd:d9:dd:c25:c25:600a:1630/1242c19:dd:d9:dd:c25:c25:600a:163f
1012c19:dd:d9:dd:c25:c25:600a:1640/1242c19:dd:d9:dd:c25:c25:600a:164f
1022c19:dd:d9:dd:c25:c25:600a:1650/1242c19:dd:d9:dd:c25:c25:600a:165f
1032c19:dd:d9:dd:c25:c25:600a:1660/1242c19:dd:d9:dd:c25:c25:600a:166f
1042c19:dd:d9:dd:c25:c25:600a:1670/1242c19:dd:d9:dd:c25:c25:600a:167f
1052c19:dd:d9:dd:c25:c25:600a:1680/1242c19:dd:d9:dd:c25:c25:600a:168f
1062c19:dd:d9:dd:c25:c25:600a:1690/1242c19:dd:d9:dd:c25:c25:600a:169f
1072c19:dd:d9:dd:c25:c25:600a:16a0/1242c19:dd:d9:dd:c25:c25:600a:16af
1082c19:dd:d9:dd:c25:c25:600a:16b0/1242c19:dd:d9:dd:c25:c25:600a:16bf
1092c19:dd:d9:dd:c25:c25:600a:16c0/1242c19:dd:d9:dd:c25:c25:600a:16cf
1102c19:dd:d9:dd:c25:c25:600a:16d0/1242c19:dd:d9:dd:c25:c25:600a:16df
1112c19:dd:d9:dd:c25:c25:600a:16e0/1242c19:dd:d9:dd:c25:c25:600a:16ef
1122c19:dd:d9:dd:c25:c25:600a:16f0/1242c19:dd:d9:dd:c25:c25:600a:16ff
1132c19:dd:d9:dd:c25:c25:600a:1700/1242c19:dd:d9:dd:c25:c25:600a:170f
1142c19:dd:d9:dd:c25:c25:600a:1710/1242c19:dd:d9:dd:c25:c25:600a:171f
1152c19:dd:d9:dd:c25:c25:600a:1720/1242c19:dd:d9:dd:c25:c25:600a:172f
1162c19:dd:d9:dd:c25:c25:600a:1730/1242c19:dd:d9:dd:c25:c25:600a:173f
1172c19:dd:d9:dd:c25:c25:600a:1740/1242c19:dd:d9:dd:c25:c25:600a:174f
1182c19:dd:d9:dd:c25:c25:600a:1750/1242c19:dd:d9:dd:c25:c25:600a:175f
1192c19:dd:d9:dd:c25:c25:600a:1760/1242c19:dd:d9:dd:c25:c25:600a:176f
1202c19:dd:d9:dd:c25:c25:600a:1770/1242c19:dd:d9:dd:c25:c25:600a:177f
1212c19:dd:d9:dd:c25:c25:600a:1780/1242c19:dd:d9:dd:c25:c25:600a:178f
1222c19:dd:d9:dd:c25:c25:600a:1790/1242c19:dd:d9:dd:c25:c25:600a:179f
1232c19:dd:d9:dd:c25:c25:600a:17a0/1242c19:dd:d9:dd:c25:c25:600a:17af
1242c19:dd:d9:dd:c25:c25:600a:17b0/1242c19:dd:d9:dd:c25:c25:600a:17bf
1252c19:dd:d9:dd:c25:c25:600a:17c0/1242c19:dd:d9:dd:c25:c25:600a:17cf
1262c19:dd:d9:dd:c25:c25:600a:17d0/1242c19:dd:d9:dd:c25:c25:600a:17df
1272c19:dd:d9:dd:c25:c25:600a:17e0/1242c19:dd:d9:dd:c25:c25:600a:17ef
1282c19:dd:d9:dd:c25:c25:600a:17f0/1242c19:dd:d9:dd:c25:c25:600a:17ff
1292c19:dd:d9:dd:c25:c25:600a:1800/1242c19:dd:d9:dd:c25:c25:600a:180f
1302c19:dd:d9:dd:c25:c25:600a:1810/1242c19:dd:d9:dd:c25:c25:600a:181f
1312c19:dd:d9:dd:c25:c25:600a:1820/1242c19:dd:d9:dd:c25:c25:600a:182f
1322c19:dd:d9:dd:c25:c25:600a:1830/1242c19:dd:d9:dd:c25:c25:600a:183f
1332c19:dd:d9:dd:c25:c25:600a:1840/1242c19:dd:d9:dd:c25:c25:600a:184f
1342c19:dd:d9:dd:c25:c25:600a:1850/1242c19:dd:d9:dd:c25:c25:600a:185f
1352c19:dd:d9:dd:c25:c25:600a:1860/1242c19:dd:d9:dd:c25:c25:600a:186f
1362c19:dd:d9:dd:c25:c25:600a:1870/1242c19:dd:d9:dd:c25:c25:600a:187f
1372c19:dd:d9:dd:c25:c25:600a:1880/1242c19:dd:d9:dd:c25:c25:600a:188f
1382c19:dd:d9:dd:c25:c25:600a:1890/1242c19:dd:d9:dd:c25:c25:600a:189f
1392c19:dd:d9:dd:c25:c25:600a:18a0/1242c19:dd:d9:dd:c25:c25:600a:18af
1402c19:dd:d9:dd:c25:c25:600a:18b0/1242c19:dd:d9:dd:c25:c25:600a:18bf
1412c19:dd:d9:dd:c25:c25:600a:18c0/1242c19:dd:d9:dd:c25:c25:600a:18cf
1422c19:dd:d9:dd:c25:c25:600a:18d0/1242c19:dd:d9:dd:c25:c25:600a:18df
1432c19:dd:d9:dd:c25:c25:600a:18e0/1242c19:dd:d9:dd:c25:c25:600a:18ef
1442c19:dd:d9:dd:c25:c25:600a:18f0/1242c19:dd:d9:dd:c25:c25:600a:18ff
1452c19:dd:d9:dd:c25:c25:600a:1900/1242c19:dd:d9:dd:c25:c25:600a:190f
1462c19:dd:d9:dd:c25:c25:600a:1910/1242c19:dd:d9:dd:c25:c25:600a:191f
1472c19:dd:d9:dd:c25:c25:600a:1920/1242c19:dd:d9:dd:c25:c25:600a:192f
1482c19:dd:d9:dd:c25:c25:600a:1930/1242c19:dd:d9:dd:c25:c25:600a:193f
1492c19:dd:d9:dd:c25:c25:600a:1940/1242c19:dd:d9:dd:c25:c25:600a:194f
1502c19:dd:d9:dd:c25:c25:600a:1950/1242c19:dd:d9:dd:c25:c25:600a:195f
1512c19:dd:d9:dd:c25:c25:600a:1960/1242c19:dd:d9:dd:c25:c25:600a:196f
1522c19:dd:d9:dd:c25:c25:600a:1970/1242c19:dd:d9:dd:c25:c25:600a:197f
1532c19:dd:d9:dd:c25:c25:600a:1980/1242c19:dd:d9:dd:c25:c25:600a:198f
1542c19:dd:d9:dd:c25:c25:600a:1990/1242c19:dd:d9:dd:c25:c25:600a:199f
1552c19:dd:d9:dd:c25:c25:600a:19a0/1242c19:dd:d9:dd:c25:c25:600a:19af
1562c19:dd:d9:dd:c25:c25:600a:19b0/1242c19:dd:d9:dd:c25:c25:600a:19bf
1572c19:dd:d9:dd:c25:c25:600a:19c0/1242c19:dd:d9:dd:c25:c25:600a:19cf
1582c19:dd:d9:dd:c25:c25:600a:19d0/1242c19:dd:d9:dd:c25:c25:600a:19df
1592c19:dd:d9:dd:c25:c25:600a:19e0/1242c19:dd:d9:dd:c25:c25:600a:19ef
1602c19:dd:d9:dd:c25:c25:600a:19f0/1242c19:dd:d9:dd:c25:c25:600a:19ff
1612c19:dd:d9:dd:c25:c25:600a:1a00/1242c19:dd:d9:dd:c25:c25:600a:1a0f
1622c19:dd:d9:dd:c25:c25:600a:1a10/1242c19:dd:d9:dd:c25:c25:600a:1a1f
1632c19:dd:d9:dd:c25:c25:600a:1a20/1242c19:dd:d9:dd:c25:c25:600a:1a2f
1642c19:dd:d9:dd:c25:c25:600a:1a30/1242c19:dd:d9:dd:c25:c25:600a:1a3f
1652c19:dd:d9:dd:c25:c25:600a:1a40/1242c19:dd:d9:dd:c25:c25:600a:1a4f
1662c19:dd:d9:dd:c25:c25:600a:1a50/1242c19:dd:d9:dd:c25:c25:600a:1a5f
1672c19:dd:d9:dd:c25:c25:600a:1a60/1242c19:dd:d9:dd:c25:c25:600a:1a6f
1682c19:dd:d9:dd:c25:c25:600a:1a70/1242c19:dd:d9:dd:c25:c25:600a:1a7f
1692c19:dd:d9:dd:c25:c25:600a:1a80/1242c19:dd:d9:dd:c25:c25:600a:1a8f
1702c19:dd:d9:dd:c25:c25:600a:1a90/1242c19:dd:d9:dd:c25:c25:600a:1a9f
1712c19:dd:d9:dd:c25:c25:600a:1aa0/1242c19:dd:d9:dd:c25:c25:600a:1aaf
1722c19:dd:d9:dd:c25:c25:600a:1ab0/1242c19:dd:d9:dd:c25:c25:600a:1abf
1732c19:dd:d9:dd:c25:c25:600a:1ac0/1242c19:dd:d9:dd:c25:c25:600a:1acf
1742c19:dd:d9:dd:c25:c25:600a:1ad0/1242c19:dd:d9:dd:c25:c25:600a:1adf
1752c19:dd:d9:dd:c25:c25:600a:1ae0/1242c19:dd:d9:dd:c25:c25:600a:1aef
1762c19:dd:d9:dd:c25:c25:600a:1af0/1242c19:dd:d9:dd:c25:c25:600a:1aff
1772c19:dd:d9:dd:c25:c25:600a:1b00/1242c19:dd:d9:dd:c25:c25:600a:1b0f
1782c19:dd:d9:dd:c25:c25:600a:1b10/1242c19:dd:d9:dd:c25:c25:600a:1b1f
1792c19:dd:d9:dd:c25:c25:600a:1b20/1242c19:dd:d9:dd:c25:c25:600a:1b2f
1802c19:dd:d9:dd:c25:c25:600a:1b30/1242c19:dd:d9:dd:c25:c25:600a:1b3f
1812c19:dd:d9:dd:c25:c25:600a:1b40/1242c19:dd:d9:dd:c25:c25:600a:1b4f
1822c19:dd:d9:dd:c25:c25:600a:1b50/1242c19:dd:d9:dd:c25:c25:600a:1b5f
1832c19:dd:d9:dd:c25:c25:600a:1b60/1242c19:dd:d9:dd:c25:c25:600a:1b6f
1842c19:dd:d9:dd:c25:c25:600a:1b70/1242c19:dd:d9:dd:c25:c25:600a:1b7f
1852c19:dd:d9:dd:c25:c25:600a:1b80/1242c19:dd:d9:dd:c25:c25:600a:1b8f
1862c19:dd:d9:dd:c25:c25:600a:1b90/1242c19:dd:d9:dd:c25:c25:600a:1b9f
1872c19:dd:d9:dd:c25:c25:600a:1ba0/1242c19:dd:d9:dd:c25:c25:600a:1baf
1882c19:dd:d9:dd:c25:c25:600a:1bb0/1242c19:dd:d9:dd:c25:c25:600a:1bbf
1892c19:dd:d9:dd:c25:c25:600a:1bc0/1242c19:dd:d9:dd:c25:c25:600a:1bcf
1902c19:dd:d9:dd:c25:c25:600a:1bd0/1242c19:dd:d9:dd:c25:c25:600a:1bdf
1912c19:dd:d9:dd:c25:c25:600a:1be0/1242c19:dd:d9:dd:c25:c25:600a:1bef
1922c19:dd:d9:dd:c25:c25:600a:1bf0/1242c19:dd:d9:dd:c25:c25:600a:1bff
1932c19:dd:d9:dd:c25:c25:600a:1c00/1242c19:dd:d9:dd:c25:c25:600a:1c0f
1942c19:dd:d9:dd:c25:c25:600a:1c10/1242c19:dd:d9:dd:c25:c25:600a:1c1f
1952c19:dd:d9:dd:c25:c25:600a:1c20/1242c19:dd:d9:dd:c25:c25:600a:1c2f
1962c19:dd:d9:dd:c25:c25:600a:1c30/1242c19:dd:d9:dd:c25:c25:600a:1c3f
1972c19:dd:d9:dd:c25:c25:600a:1c40/1242c19:dd:d9:dd:c25:c25:600a:1c4f
1982c19:dd:d9:dd:c25:c25:600a:1c50/1242c19:dd:d9:dd:c25:c25:600a:1c5f
1992c19:dd:d9:dd:c25:c25:600a:1c60/1242c19:dd:d9:dd:c25:c25:600a:1c6f
2002c19:dd:d9:dd:c25:c25:600a:1c70/1242c19:dd:d9:dd:c25:c25:600a:1c7f
2012c19:dd:d9:dd:c25:c25:600a:1c80/1242c19:dd:d9:dd:c25:c25:600a:1c8f
2022c19:dd:d9:dd:c25:c25:600a:1c90/1242c19:dd:d9:dd:c25:c25:600a:1c9f
2032c19:dd:d9:dd:c25:c25:600a:1ca0/1242c19:dd:d9:dd:c25:c25:600a:1caf
2042c19:dd:d9:dd:c25:c25:600a:1cb0/1242c19:dd:d9:dd:c25:c25:600a:1cbf
2052c19:dd:d9:dd:c25:c25:600a:1cc0/1242c19:dd:d9:dd:c25:c25:600a:1ccf
2062c19:dd:d9:dd:c25:c25:600a:1cd0/1242c19:dd:d9:dd:c25:c25:600a:1cdf
2072c19:dd:d9:dd:c25:c25:600a:1ce0/1242c19:dd:d9:dd:c25:c25:600a:1cef
2082c19:dd:d9:dd:c25:c25:600a:1cf0/1242c19:dd:d9:dd:c25:c25:600a:1cff
2092c19:dd:d9:dd:c25:c25:600a:1d00/1242c19:dd:d9:dd:c25:c25:600a:1d0f
2102c19:dd:d9:dd:c25:c25:600a:1d10/1242c19:dd:d9:dd:c25:c25:600a:1d1f
2112c19:dd:d9:dd:c25:c25:600a:1d20/1242c19:dd:d9:dd:c25:c25:600a:1d2f
2122c19:dd:d9:dd:c25:c25:600a:1d30/1242c19:dd:d9:dd:c25:c25:600a:1d3f
2132c19:dd:d9:dd:c25:c25:600a:1d40/1242c19:dd:d9:dd:c25:c25:600a:1d4f
2142c19:dd:d9:dd:c25:c25:600a:1d50/1242c19:dd:d9:dd:c25:c25:600a:1d5f
2152c19:dd:d9:dd:c25:c25:600a:1d60/1242c19:dd:d9:dd:c25:c25:600a:1d6f
2162c19:dd:d9:dd:c25:c25:600a:1d70/1242c19:dd:d9:dd:c25:c25:600a:1d7f
2172c19:dd:d9:dd:c25:c25:600a:1d80/1242c19:dd:d9:dd:c25:c25:600a:1d8f
2182c19:dd:d9:dd:c25:c25:600a:1d90/1242c19:dd:d9:dd:c25:c25:600a:1d9f
2192c19:dd:d9:dd:c25:c25:600a:1da0/1242c19:dd:d9:dd:c25:c25:600a:1daf
2202c19:dd:d9:dd:c25:c25:600a:1db0/1242c19:dd:d9:dd:c25:c25:600a:1dbf
2212c19:dd:d9:dd:c25:c25:600a:1dc0/1242c19:dd:d9:dd:c25:c25:600a:1dcf
2222c19:dd:d9:dd:c25:c25:600a:1dd0/1242c19:dd:d9:dd:c25:c25:600a:1ddf
2232c19:dd:d9:dd:c25:c25:600a:1de0/1242c19:dd:d9:dd:c25:c25:600a:1def
2242c19:dd:d9:dd:c25:c25:600a:1df0/1242c19:dd:d9:dd:c25:c25:600a:1dff
2252c19:dd:d9:dd:c25:c25:600a:1e00/1242c19:dd:d9:dd:c25:c25:600a:1e0f
2262c19:dd:d9:dd:c25:c25:600a:1e10/1242c19:dd:d9:dd:c25:c25:600a:1e1f
2272c19:dd:d9:dd:c25:c25:600a:1e20/1242c19:dd:d9:dd:c25:c25:600a:1e2f
2282c19:dd:d9:dd:c25:c25:600a:1e30/1242c19:dd:d9:dd:c25:c25:600a:1e3f
2292c19:dd:d9:dd:c25:c25:600a:1e40/1242c19:dd:d9:dd:c25:c25:600a:1e4f
2302c19:dd:d9:dd:c25:c25:600a:1e50/1242c19:dd:d9:dd:c25:c25:600a:1e5f
2312c19:dd:d9:dd:c25:c25:600a:1e60/1242c19:dd:d9:dd:c25:c25:600a:1e6f
2322c19:dd:d9:dd:c25:c25:600a:1e70/1242c19:dd:d9:dd:c25:c25:600a:1e7f
2332c19:dd:d9:dd:c25:c25:600a:1e80/1242c19:dd:d9:dd:c25:c25:600a:1e8f
2342c19:dd:d9:dd:c25:c25:600a:1e90/1242c19:dd:d9:dd:c25:c25:600a:1e9f
2352c19:dd:d9:dd:c25:c25:600a:1ea0/1242c19:dd:d9:dd:c25:c25:600a:1eaf
2362c19:dd:d9:dd:c25:c25:600a:1eb0/1242c19:dd:d9:dd:c25:c25:600a:1ebf
2372c19:dd:d9:dd:c25:c25:600a:1ec0/1242c19:dd:d9:dd:c25:c25:600a:1ecf
2382c19:dd:d9:dd:c25:c25:600a:1ed0/1242c19:dd:d9:dd:c25:c25:600a:1edf
2392c19:dd:d9:dd:c25:c25:600a:1ee0/1242c19:dd:d9:dd:c25:c25:600a:1eef
2402c19:dd:d9:dd:c25:c25:600a:1ef0/1242c19:dd:d9:dd:c25:c25:600a:1eff
2412c19:dd:d9:dd:c25:c25:600a:1f00/1242c19:dd:d9:dd:c25:c25:600a:1f0f
2422c19:dd:d9:dd:c25:c25:600a:1f10/1242c19:dd:d9:dd:c25:c25:600a:1f1f
2432c19:dd:d9:dd:c25:c25:600a:1f20/1242c19:dd:d9:dd:c25:c25:600a:1f2f
2442c19:dd:d9:dd:c25:c25:600a:1f30/1242c19:dd:d9:dd:c25:c25:600a:1f3f
2452c19:dd:d9:dd:c25:c25:600a:1f40/1242c19:dd:d9:dd:c25:c25:600a:1f4f
2462c19:dd:d9:dd:c25:c25:600a:1f50/1242c19:dd:d9:dd:c25:c25:600a:1f5f
2472c19:dd:d9:dd:c25:c25:600a:1f60/1242c19:dd:d9:dd:c25:c25:600a:1f6f
2482c19:dd:d9:dd:c25:c25:600a:1f70/1242c19:dd:d9:dd:c25:c25:600a:1f7f
2492c19:dd:d9:dd:c25:c25:600a:1f80/1242c19:dd:d9:dd:c25:c25:600a:1f8f
2502c19:dd:d9:dd:c25:c25:600a:1f90/1242c19:dd:d9:dd:c25:c25:600a:1f9f
2512c19:dd:d9:dd:c25:c25:600a:1fa0/1242c19:dd:d9:dd:c25:c25:600a:1faf
2522c19:dd:d9:dd:c25:c25:600a:1fb0/1242c19:dd:d9:dd:c25:c25:600a:1fbf
2532c19:dd:d9:dd:c25:c25:600a:1fc0/1242c19:dd:d9:dd:c25:c25:600a:1fcf
2542c19:dd:d9:dd:c25:c25:600a:1fd0/1242c19:dd:d9:dd:c25:c25:600a:1fdf
2552c19:dd:d9:dd:c25:c25:600a:1fe0/1242c19:dd:d9:dd:c25:c25:600a:1fef
2562c19:dd:d9:dd:c25:c25:600a:1ff0/1242c19:dd:d9:dd:c25:c25:600a:1fff

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.