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/112
Addresses65,536
/64 networksPart of one
Network
2c19:dd:d9:dd:c25:c25:e051:0/112
First address
2c19:dd:d9:dd:c25:c25:e051:0
Last address
2c19:dd:d9:dd:c25:c25:e051:ffff
Addresses
65,536
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:e051:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
1.5.0.e.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/127
/113 (2)/114 (4)/115 (8)/116 (16)/120 (256)/124 (4,096)/127 (32,768)/128 (65,536)

2c19:dd:d9:dd:c25:c25:e051:0/112 makes 32,768 subnets of /127; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:e051:0/1272c19:dd:d9:dd:c25:c25:e051:1
22c19:dd:d9:dd:c25:c25:e051:2/1272c19:dd:d9:dd:c25:c25:e051:3
32c19:dd:d9:dd:c25:c25:e051:4/1272c19:dd:d9:dd:c25:c25:e051:5
42c19:dd:d9:dd:c25:c25:e051:6/1272c19:dd:d9:dd:c25:c25:e051:7
52c19:dd:d9:dd:c25:c25:e051:8/1272c19:dd:d9:dd:c25:c25:e051:9
62c19:dd:d9:dd:c25:c25:e051:a/1272c19:dd:d9:dd:c25:c25:e051:b
72c19:dd:d9:dd:c25:c25:e051:c/1272c19:dd:d9:dd:c25:c25:e051:d
82c19:dd:d9:dd:c25:c25:e051:e/1272c19:dd:d9:dd:c25:c25:e051:f
92c19:dd:d9:dd:c25:c25:e051:10/1272c19:dd:d9:dd:c25:c25:e051:11
102c19:dd:d9:dd:c25:c25:e051:12/1272c19:dd:d9:dd:c25:c25:e051:13
112c19:dd:d9:dd:c25:c25:e051:14/1272c19:dd:d9:dd:c25:c25:e051:15
122c19:dd:d9:dd:c25:c25:e051:16/1272c19:dd:d9:dd:c25:c25:e051:17
132c19:dd:d9:dd:c25:c25:e051:18/1272c19:dd:d9:dd:c25:c25:e051:19
142c19:dd:d9:dd:c25:c25:e051:1a/1272c19:dd:d9:dd:c25:c25:e051:1b
152c19:dd:d9:dd:c25:c25:e051:1c/1272c19:dd:d9:dd:c25:c25:e051:1d
162c19:dd:d9:dd:c25:c25:e051:1e/1272c19:dd:d9:dd:c25:c25:e051:1f
172c19:dd:d9:dd:c25:c25:e051:20/1272c19:dd:d9:dd:c25:c25:e051:21
182c19:dd:d9:dd:c25:c25:e051:22/1272c19:dd:d9:dd:c25:c25:e051:23
192c19:dd:d9:dd:c25:c25:e051:24/1272c19:dd:d9:dd:c25:c25:e051:25
202c19:dd:d9:dd:c25:c25:e051:26/1272c19:dd:d9:dd:c25:c25:e051:27
212c19:dd:d9:dd:c25:c25:e051:28/1272c19:dd:d9:dd:c25:c25:e051:29
222c19:dd:d9:dd:c25:c25:e051:2a/1272c19:dd:d9:dd:c25:c25:e051:2b
232c19:dd:d9:dd:c25:c25:e051:2c/1272c19:dd:d9:dd:c25:c25:e051:2d
242c19:dd:d9:dd:c25:c25:e051:2e/1272c19:dd:d9:dd:c25:c25:e051:2f
252c19:dd:d9:dd:c25:c25:e051:30/1272c19:dd:d9:dd:c25:c25:e051:31
262c19:dd:d9:dd:c25:c25:e051:32/1272c19:dd:d9:dd:c25:c25:e051:33
272c19:dd:d9:dd:c25:c25:e051:34/1272c19:dd:d9:dd:c25:c25:e051:35
282c19:dd:d9:dd:c25:c25:e051:36/1272c19:dd:d9:dd:c25:c25:e051:37
292c19:dd:d9:dd:c25:c25:e051:38/1272c19:dd:d9:dd:c25:c25:e051:39
302c19:dd:d9:dd:c25:c25:e051:3a/1272c19:dd:d9:dd:c25:c25:e051:3b
312c19:dd:d9:dd:c25:c25:e051:3c/1272c19:dd:d9:dd:c25:c25:e051:3d
322c19:dd:d9:dd:c25:c25:e051:3e/1272c19:dd:d9:dd:c25:c25:e051:3f
332c19:dd:d9:dd:c25:c25:e051:40/1272c19:dd:d9:dd:c25:c25:e051:41
342c19:dd:d9:dd:c25:c25:e051:42/1272c19:dd:d9:dd:c25:c25:e051:43
352c19:dd:d9:dd:c25:c25:e051:44/1272c19:dd:d9:dd:c25:c25:e051:45
362c19:dd:d9:dd:c25:c25:e051:46/1272c19:dd:d9:dd:c25:c25:e051:47
372c19:dd:d9:dd:c25:c25:e051:48/1272c19:dd:d9:dd:c25:c25:e051:49
382c19:dd:d9:dd:c25:c25:e051:4a/1272c19:dd:d9:dd:c25:c25:e051:4b
392c19:dd:d9:dd:c25:c25:e051:4c/1272c19:dd:d9:dd:c25:c25:e051:4d
402c19:dd:d9:dd:c25:c25:e051:4e/1272c19:dd:d9:dd:c25:c25:e051:4f
412c19:dd:d9:dd:c25:c25:e051:50/1272c19:dd:d9:dd:c25:c25:e051:51
422c19:dd:d9:dd:c25:c25:e051:52/1272c19:dd:d9:dd:c25:c25:e051:53
432c19:dd:d9:dd:c25:c25:e051:54/1272c19:dd:d9:dd:c25:c25:e051:55
442c19:dd:d9:dd:c25:c25:e051:56/1272c19:dd:d9:dd:c25:c25:e051:57
452c19:dd:d9:dd:c25:c25:e051:58/1272c19:dd:d9:dd:c25:c25:e051:59
462c19:dd:d9:dd:c25:c25:e051:5a/1272c19:dd:d9:dd:c25:c25:e051:5b
472c19:dd:d9:dd:c25:c25:e051:5c/1272c19:dd:d9:dd:c25:c25:e051:5d
482c19:dd:d9:dd:c25:c25:e051:5e/1272c19:dd:d9:dd:c25:c25:e051:5f
492c19:dd:d9:dd:c25:c25:e051:60/1272c19:dd:d9:dd:c25:c25:e051:61
502c19:dd:d9:dd:c25:c25:e051:62/1272c19:dd:d9:dd:c25:c25:e051:63
512c19:dd:d9:dd:c25:c25:e051:64/1272c19:dd:d9:dd:c25:c25:e051:65
522c19:dd:d9:dd:c25:c25:e051:66/1272c19:dd:d9:dd:c25:c25:e051:67
532c19:dd:d9:dd:c25:c25:e051:68/1272c19:dd:d9:dd:c25:c25:e051:69
542c19:dd:d9:dd:c25:c25:e051:6a/1272c19:dd:d9:dd:c25:c25:e051:6b
552c19:dd:d9:dd:c25:c25:e051:6c/1272c19:dd:d9:dd:c25:c25:e051:6d
562c19:dd:d9:dd:c25:c25:e051:6e/1272c19:dd:d9:dd:c25:c25:e051:6f
572c19:dd:d9:dd:c25:c25:e051:70/1272c19:dd:d9:dd:c25:c25:e051:71
582c19:dd:d9:dd:c25:c25:e051:72/1272c19:dd:d9:dd:c25:c25:e051:73
592c19:dd:d9:dd:c25:c25:e051:74/1272c19:dd:d9:dd:c25:c25:e051:75
602c19:dd:d9:dd:c25:c25:e051:76/1272c19:dd:d9:dd:c25:c25:e051:77
612c19:dd:d9:dd:c25:c25:e051:78/1272c19:dd:d9:dd:c25:c25:e051:79
622c19:dd:d9:dd:c25:c25:e051:7a/1272c19:dd:d9:dd:c25:c25:e051:7b
632c19:dd:d9:dd:c25:c25:e051:7c/1272c19:dd:d9:dd:c25:c25:e051:7d
642c19:dd:d9:dd:c25:c25:e051:7e/1272c19:dd:d9:dd:c25:c25:e051:7f
652c19:dd:d9:dd:c25:c25:e051:80/1272c19:dd:d9:dd:c25:c25:e051:81
662c19:dd:d9:dd:c25:c25:e051:82/1272c19:dd:d9:dd:c25:c25:e051:83
672c19:dd:d9:dd:c25:c25:e051:84/1272c19:dd:d9:dd:c25:c25:e051:85
682c19:dd:d9:dd:c25:c25:e051:86/1272c19:dd:d9:dd:c25:c25:e051:87
692c19:dd:d9:dd:c25:c25:e051:88/1272c19:dd:d9:dd:c25:c25:e051:89
702c19:dd:d9:dd:c25:c25:e051:8a/1272c19:dd:d9:dd:c25:c25:e051:8b
712c19:dd:d9:dd:c25:c25:e051:8c/1272c19:dd:d9:dd:c25:c25:e051:8d
722c19:dd:d9:dd:c25:c25:e051:8e/1272c19:dd:d9:dd:c25:c25:e051:8f
732c19:dd:d9:dd:c25:c25:e051:90/1272c19:dd:d9:dd:c25:c25:e051:91
742c19:dd:d9:dd:c25:c25:e051:92/1272c19:dd:d9:dd:c25:c25:e051:93
752c19:dd:d9:dd:c25:c25:e051:94/1272c19:dd:d9:dd:c25:c25:e051:95
762c19:dd:d9:dd:c25:c25:e051:96/1272c19:dd:d9:dd:c25:c25:e051:97
772c19:dd:d9:dd:c25:c25:e051:98/1272c19:dd:d9:dd:c25:c25:e051:99
782c19:dd:d9:dd:c25:c25:e051:9a/1272c19:dd:d9:dd:c25:c25:e051:9b
792c19:dd:d9:dd:c25:c25:e051:9c/1272c19:dd:d9:dd:c25:c25:e051:9d
802c19:dd:d9:dd:c25:c25:e051:9e/1272c19:dd:d9:dd:c25:c25:e051:9f
812c19:dd:d9:dd:c25:c25:e051:a0/1272c19:dd:d9:dd:c25:c25:e051:a1
822c19:dd:d9:dd:c25:c25:e051:a2/1272c19:dd:d9:dd:c25:c25:e051:a3
832c19:dd:d9:dd:c25:c25:e051:a4/1272c19:dd:d9:dd:c25:c25:e051:a5
842c19:dd:d9:dd:c25:c25:e051:a6/1272c19:dd:d9:dd:c25:c25:e051:a7
852c19:dd:d9:dd:c25:c25:e051:a8/1272c19:dd:d9:dd:c25:c25:e051:a9
862c19:dd:d9:dd:c25:c25:e051:aa/1272c19:dd:d9:dd:c25:c25:e051:ab
872c19:dd:d9:dd:c25:c25:e051:ac/1272c19:dd:d9:dd:c25:c25:e051:ad
882c19:dd:d9:dd:c25:c25:e051:ae/1272c19:dd:d9:dd:c25:c25:e051:af
892c19:dd:d9:dd:c25:c25:e051:b0/1272c19:dd:d9:dd:c25:c25:e051:b1
902c19:dd:d9:dd:c25:c25:e051:b2/1272c19:dd:d9:dd:c25:c25:e051:b3
912c19:dd:d9:dd:c25:c25:e051:b4/1272c19:dd:d9:dd:c25:c25:e051:b5
922c19:dd:d9:dd:c25:c25:e051:b6/1272c19:dd:d9:dd:c25:c25:e051:b7
932c19:dd:d9:dd:c25:c25:e051:b8/1272c19:dd:d9:dd:c25:c25:e051:b9
942c19:dd:d9:dd:c25:c25:e051:ba/1272c19:dd:d9:dd:c25:c25:e051:bb
952c19:dd:d9:dd:c25:c25:e051:bc/1272c19:dd:d9:dd:c25:c25:e051:bd
962c19:dd:d9:dd:c25:c25:e051:be/1272c19:dd:d9:dd:c25:c25:e051:bf
972c19:dd:d9:dd:c25:c25:e051:c0/1272c19:dd:d9:dd:c25:c25:e051:c1
982c19:dd:d9:dd:c25:c25:e051:c2/1272c19:dd:d9:dd:c25:c25:e051:c3
992c19:dd:d9:dd:c25:c25:e051:c4/1272c19:dd:d9:dd:c25:c25:e051:c5
1002c19:dd:d9:dd:c25:c25:e051:c6/1272c19:dd:d9:dd:c25:c25:e051:c7
1012c19:dd:d9:dd:c25:c25:e051:c8/1272c19:dd:d9:dd:c25:c25:e051:c9
1022c19:dd:d9:dd:c25:c25:e051:ca/1272c19:dd:d9:dd:c25:c25:e051:cb
1032c19:dd:d9:dd:c25:c25:e051:cc/1272c19:dd:d9:dd:c25:c25:e051:cd
1042c19:dd:d9:dd:c25:c25:e051:ce/1272c19:dd:d9:dd:c25:c25:e051:cf
1052c19:dd:d9:dd:c25:c25:e051:d0/1272c19:dd:d9:dd:c25:c25:e051:d1
1062c19:dd:d9:dd:c25:c25:e051:d2/1272c19:dd:d9:dd:c25:c25:e051:d3
1072c19:dd:d9:dd:c25:c25:e051:d4/1272c19:dd:d9:dd:c25:c25:e051:d5
1082c19:dd:d9:dd:c25:c25:e051:d6/1272c19:dd:d9:dd:c25:c25:e051:d7
1092c19:dd:d9:dd:c25:c25:e051:d8/1272c19:dd:d9:dd:c25:c25:e051:d9
1102c19:dd:d9:dd:c25:c25:e051:da/1272c19:dd:d9:dd:c25:c25:e051:db
1112c19:dd:d9:dd:c25:c25:e051:dc/1272c19:dd:d9:dd:c25:c25:e051:dd
1122c19:dd:d9:dd:c25:c25:e051:de/1272c19:dd:d9:dd:c25:c25:e051:df
1132c19:dd:d9:dd:c25:c25:e051:e0/1272c19:dd:d9:dd:c25:c25:e051:e1
1142c19:dd:d9:dd:c25:c25:e051:e2/1272c19:dd:d9:dd:c25:c25:e051:e3
1152c19:dd:d9:dd:c25:c25:e051:e4/1272c19:dd:d9:dd:c25:c25:e051:e5
1162c19:dd:d9:dd:c25:c25:e051:e6/1272c19:dd:d9:dd:c25:c25:e051:e7
1172c19:dd:d9:dd:c25:c25:e051:e8/1272c19:dd:d9:dd:c25:c25:e051:e9
1182c19:dd:d9:dd:c25:c25:e051:ea/1272c19:dd:d9:dd:c25:c25:e051:eb
1192c19:dd:d9:dd:c25:c25:e051:ec/1272c19:dd:d9:dd:c25:c25:e051:ed
1202c19:dd:d9:dd:c25:c25:e051:ee/1272c19:dd:d9:dd:c25:c25:e051:ef
1212c19:dd:d9:dd:c25:c25:e051:f0/1272c19:dd:d9:dd:c25:c25:e051:f1
1222c19:dd:d9:dd:c25:c25:e051:f2/1272c19:dd:d9:dd:c25:c25:e051:f3
1232c19:dd:d9:dd:c25:c25:e051:f4/1272c19:dd:d9:dd:c25:c25:e051:f5
1242c19:dd:d9:dd:c25:c25:e051:f6/1272c19:dd:d9:dd:c25:c25:e051:f7
1252c19:dd:d9:dd:c25:c25:e051:f8/1272c19:dd:d9:dd:c25:c25:e051:f9
1262c19:dd:d9:dd:c25:c25:e051:fa/1272c19:dd:d9:dd:c25:c25:e051:fb
1272c19:dd:d9:dd:c25:c25:e051:fc/1272c19:dd:d9:dd:c25:c25:e051:fd
1282c19:dd:d9:dd:c25:c25:e051:fe/1272c19:dd:d9:dd:c25:c25:e051:ff
1292c19:dd:d9:dd:c25:c25:e051:100/1272c19:dd:d9:dd:c25:c25:e051:101
1302c19:dd:d9:dd:c25:c25:e051:102/1272c19:dd:d9:dd:c25:c25:e051:103
1312c19:dd:d9:dd:c25:c25:e051:104/1272c19:dd:d9:dd:c25:c25:e051:105
1322c19:dd:d9:dd:c25:c25:e051:106/1272c19:dd:d9:dd:c25:c25:e051:107
1332c19:dd:d9:dd:c25:c25:e051:108/1272c19:dd:d9:dd:c25:c25:e051:109
1342c19:dd:d9:dd:c25:c25:e051:10a/1272c19:dd:d9:dd:c25:c25:e051:10b
1352c19:dd:d9:dd:c25:c25:e051:10c/1272c19:dd:d9:dd:c25:c25:e051:10d
1362c19:dd:d9:dd:c25:c25:e051:10e/1272c19:dd:d9:dd:c25:c25:e051:10f
1372c19:dd:d9:dd:c25:c25:e051:110/1272c19:dd:d9:dd:c25:c25:e051:111
1382c19:dd:d9:dd:c25:c25:e051:112/1272c19:dd:d9:dd:c25:c25:e051:113
1392c19:dd:d9:dd:c25:c25:e051:114/1272c19:dd:d9:dd:c25:c25:e051:115
1402c19:dd:d9:dd:c25:c25:e051:116/1272c19:dd:d9:dd:c25:c25:e051:117
1412c19:dd:d9:dd:c25:c25:e051:118/1272c19:dd:d9:dd:c25:c25:e051:119
1422c19:dd:d9:dd:c25:c25:e051:11a/1272c19:dd:d9:dd:c25:c25:e051:11b
1432c19:dd:d9:dd:c25:c25:e051:11c/1272c19:dd:d9:dd:c25:c25:e051:11d
1442c19:dd:d9:dd:c25:c25:e051:11e/1272c19:dd:d9:dd:c25:c25:e051:11f
1452c19:dd:d9:dd:c25:c25:e051:120/1272c19:dd:d9:dd:c25:c25:e051:121
1462c19:dd:d9:dd:c25:c25:e051:122/1272c19:dd:d9:dd:c25:c25:e051:123
1472c19:dd:d9:dd:c25:c25:e051:124/1272c19:dd:d9:dd:c25:c25:e051:125
1482c19:dd:d9:dd:c25:c25:e051:126/1272c19:dd:d9:dd:c25:c25:e051:127
1492c19:dd:d9:dd:c25:c25:e051:128/1272c19:dd:d9:dd:c25:c25:e051:129
1502c19:dd:d9:dd:c25:c25:e051:12a/1272c19:dd:d9:dd:c25:c25:e051:12b
1512c19:dd:d9:dd:c25:c25:e051:12c/1272c19:dd:d9:dd:c25:c25:e051:12d
1522c19:dd:d9:dd:c25:c25:e051:12e/1272c19:dd:d9:dd:c25:c25:e051:12f
1532c19:dd:d9:dd:c25:c25:e051:130/1272c19:dd:d9:dd:c25:c25:e051:131
1542c19:dd:d9:dd:c25:c25:e051:132/1272c19:dd:d9:dd:c25:c25:e051:133
1552c19:dd:d9:dd:c25:c25:e051:134/1272c19:dd:d9:dd:c25:c25:e051:135
1562c19:dd:d9:dd:c25:c25:e051:136/1272c19:dd:d9:dd:c25:c25:e051:137
1572c19:dd:d9:dd:c25:c25:e051:138/1272c19:dd:d9:dd:c25:c25:e051:139
1582c19:dd:d9:dd:c25:c25:e051:13a/1272c19:dd:d9:dd:c25:c25:e051:13b
1592c19:dd:d9:dd:c25:c25:e051:13c/1272c19:dd:d9:dd:c25:c25:e051:13d
1602c19:dd:d9:dd:c25:c25:e051:13e/1272c19:dd:d9:dd:c25:c25:e051:13f
1612c19:dd:d9:dd:c25:c25:e051:140/1272c19:dd:d9:dd:c25:c25:e051:141
1622c19:dd:d9:dd:c25:c25:e051:142/1272c19:dd:d9:dd:c25:c25:e051:143
1632c19:dd:d9:dd:c25:c25:e051:144/1272c19:dd:d9:dd:c25:c25:e051:145
1642c19:dd:d9:dd:c25:c25:e051:146/1272c19:dd:d9:dd:c25:c25:e051:147
1652c19:dd:d9:dd:c25:c25:e051:148/1272c19:dd:d9:dd:c25:c25:e051:149
1662c19:dd:d9:dd:c25:c25:e051:14a/1272c19:dd:d9:dd:c25:c25:e051:14b
1672c19:dd:d9:dd:c25:c25:e051:14c/1272c19:dd:d9:dd:c25:c25:e051:14d
1682c19:dd:d9:dd:c25:c25:e051:14e/1272c19:dd:d9:dd:c25:c25:e051:14f
1692c19:dd:d9:dd:c25:c25:e051:150/1272c19:dd:d9:dd:c25:c25:e051:151
1702c19:dd:d9:dd:c25:c25:e051:152/1272c19:dd:d9:dd:c25:c25:e051:153
1712c19:dd:d9:dd:c25:c25:e051:154/1272c19:dd:d9:dd:c25:c25:e051:155
1722c19:dd:d9:dd:c25:c25:e051:156/1272c19:dd:d9:dd:c25:c25:e051:157
1732c19:dd:d9:dd:c25:c25:e051:158/1272c19:dd:d9:dd:c25:c25:e051:159
1742c19:dd:d9:dd:c25:c25:e051:15a/1272c19:dd:d9:dd:c25:c25:e051:15b
1752c19:dd:d9:dd:c25:c25:e051:15c/1272c19:dd:d9:dd:c25:c25:e051:15d
1762c19:dd:d9:dd:c25:c25:e051:15e/1272c19:dd:d9:dd:c25:c25:e051:15f
1772c19:dd:d9:dd:c25:c25:e051:160/1272c19:dd:d9:dd:c25:c25:e051:161
1782c19:dd:d9:dd:c25:c25:e051:162/1272c19:dd:d9:dd:c25:c25:e051:163
1792c19:dd:d9:dd:c25:c25:e051:164/1272c19:dd:d9:dd:c25:c25:e051:165
1802c19:dd:d9:dd:c25:c25:e051:166/1272c19:dd:d9:dd:c25:c25:e051:167
1812c19:dd:d9:dd:c25:c25:e051:168/1272c19:dd:d9:dd:c25:c25:e051:169
1822c19:dd:d9:dd:c25:c25:e051:16a/1272c19:dd:d9:dd:c25:c25:e051:16b
1832c19:dd:d9:dd:c25:c25:e051:16c/1272c19:dd:d9:dd:c25:c25:e051:16d
1842c19:dd:d9:dd:c25:c25:e051:16e/1272c19:dd:d9:dd:c25:c25:e051:16f
1852c19:dd:d9:dd:c25:c25:e051:170/1272c19:dd:d9:dd:c25:c25:e051:171
1862c19:dd:d9:dd:c25:c25:e051:172/1272c19:dd:d9:dd:c25:c25:e051:173
1872c19:dd:d9:dd:c25:c25:e051:174/1272c19:dd:d9:dd:c25:c25:e051:175
1882c19:dd:d9:dd:c25:c25:e051:176/1272c19:dd:d9:dd:c25:c25:e051:177
1892c19:dd:d9:dd:c25:c25:e051:178/1272c19:dd:d9:dd:c25:c25:e051:179
1902c19:dd:d9:dd:c25:c25:e051:17a/1272c19:dd:d9:dd:c25:c25:e051:17b
1912c19:dd:d9:dd:c25:c25:e051:17c/1272c19:dd:d9:dd:c25:c25:e051:17d
1922c19:dd:d9:dd:c25:c25:e051:17e/1272c19:dd:d9:dd:c25:c25:e051:17f
1932c19:dd:d9:dd:c25:c25:e051:180/1272c19:dd:d9:dd:c25:c25:e051:181
1942c19:dd:d9:dd:c25:c25:e051:182/1272c19:dd:d9:dd:c25:c25:e051:183
1952c19:dd:d9:dd:c25:c25:e051:184/1272c19:dd:d9:dd:c25:c25:e051:185
1962c19:dd:d9:dd:c25:c25:e051:186/1272c19:dd:d9:dd:c25:c25:e051:187
1972c19:dd:d9:dd:c25:c25:e051:188/1272c19:dd:d9:dd:c25:c25:e051:189
1982c19:dd:d9:dd:c25:c25:e051:18a/1272c19:dd:d9:dd:c25:c25:e051:18b
1992c19:dd:d9:dd:c25:c25:e051:18c/1272c19:dd:d9:dd:c25:c25:e051:18d
2002c19:dd:d9:dd:c25:c25:e051:18e/1272c19:dd:d9:dd:c25:c25:e051:18f
2012c19:dd:d9:dd:c25:c25:e051:190/1272c19:dd:d9:dd:c25:c25:e051:191
2022c19:dd:d9:dd:c25:c25:e051:192/1272c19:dd:d9:dd:c25:c25:e051:193
2032c19:dd:d9:dd:c25:c25:e051:194/1272c19:dd:d9:dd:c25:c25:e051:195
2042c19:dd:d9:dd:c25:c25:e051:196/1272c19:dd:d9:dd:c25:c25:e051:197
2052c19:dd:d9:dd:c25:c25:e051:198/1272c19:dd:d9:dd:c25:c25:e051:199
2062c19:dd:d9:dd:c25:c25:e051:19a/1272c19:dd:d9:dd:c25:c25:e051:19b
2072c19:dd:d9:dd:c25:c25:e051:19c/1272c19:dd:d9:dd:c25:c25:e051:19d
2082c19:dd:d9:dd:c25:c25:e051:19e/1272c19:dd:d9:dd:c25:c25:e051:19f
2092c19:dd:d9:dd:c25:c25:e051:1a0/1272c19:dd:d9:dd:c25:c25:e051:1a1
2102c19:dd:d9:dd:c25:c25:e051:1a2/1272c19:dd:d9:dd:c25:c25:e051:1a3
2112c19:dd:d9:dd:c25:c25:e051:1a4/1272c19:dd:d9:dd:c25:c25:e051:1a5
2122c19:dd:d9:dd:c25:c25:e051:1a6/1272c19:dd:d9:dd:c25:c25:e051:1a7
2132c19:dd:d9:dd:c25:c25:e051:1a8/1272c19:dd:d9:dd:c25:c25:e051:1a9
2142c19:dd:d9:dd:c25:c25:e051:1aa/1272c19:dd:d9:dd:c25:c25:e051:1ab
2152c19:dd:d9:dd:c25:c25:e051:1ac/1272c19:dd:d9:dd:c25:c25:e051:1ad
2162c19:dd:d9:dd:c25:c25:e051:1ae/1272c19:dd:d9:dd:c25:c25:e051:1af
2172c19:dd:d9:dd:c25:c25:e051:1b0/1272c19:dd:d9:dd:c25:c25:e051:1b1
2182c19:dd:d9:dd:c25:c25:e051:1b2/1272c19:dd:d9:dd:c25:c25:e051:1b3
2192c19:dd:d9:dd:c25:c25:e051:1b4/1272c19:dd:d9:dd:c25:c25:e051:1b5
2202c19:dd:d9:dd:c25:c25:e051:1b6/1272c19:dd:d9:dd:c25:c25:e051:1b7
2212c19:dd:d9:dd:c25:c25:e051:1b8/1272c19:dd:d9:dd:c25:c25:e051:1b9
2222c19:dd:d9:dd:c25:c25:e051:1ba/1272c19:dd:d9:dd:c25:c25:e051:1bb
2232c19:dd:d9:dd:c25:c25:e051:1bc/1272c19:dd:d9:dd:c25:c25:e051:1bd
2242c19:dd:d9:dd:c25:c25:e051:1be/1272c19:dd:d9:dd:c25:c25:e051:1bf
2252c19:dd:d9:dd:c25:c25:e051:1c0/1272c19:dd:d9:dd:c25:c25:e051:1c1
2262c19:dd:d9:dd:c25:c25:e051:1c2/1272c19:dd:d9:dd:c25:c25:e051:1c3
2272c19:dd:d9:dd:c25:c25:e051:1c4/1272c19:dd:d9:dd:c25:c25:e051:1c5
2282c19:dd:d9:dd:c25:c25:e051:1c6/1272c19:dd:d9:dd:c25:c25:e051:1c7
2292c19:dd:d9:dd:c25:c25:e051:1c8/1272c19:dd:d9:dd:c25:c25:e051:1c9
2302c19:dd:d9:dd:c25:c25:e051:1ca/1272c19:dd:d9:dd:c25:c25:e051:1cb
2312c19:dd:d9:dd:c25:c25:e051:1cc/1272c19:dd:d9:dd:c25:c25:e051:1cd
2322c19:dd:d9:dd:c25:c25:e051:1ce/1272c19:dd:d9:dd:c25:c25:e051:1cf
2332c19:dd:d9:dd:c25:c25:e051:1d0/1272c19:dd:d9:dd:c25:c25:e051:1d1
2342c19:dd:d9:dd:c25:c25:e051:1d2/1272c19:dd:d9:dd:c25:c25:e051:1d3
2352c19:dd:d9:dd:c25:c25:e051:1d4/1272c19:dd:d9:dd:c25:c25:e051:1d5
2362c19:dd:d9:dd:c25:c25:e051:1d6/1272c19:dd:d9:dd:c25:c25:e051:1d7
2372c19:dd:d9:dd:c25:c25:e051:1d8/1272c19:dd:d9:dd:c25:c25:e051:1d9
2382c19:dd:d9:dd:c25:c25:e051:1da/1272c19:dd:d9:dd:c25:c25:e051:1db
2392c19:dd:d9:dd:c25:c25:e051:1dc/1272c19:dd:d9:dd:c25:c25:e051:1dd
2402c19:dd:d9:dd:c25:c25:e051:1de/1272c19:dd:d9:dd:c25:c25:e051:1df
2412c19:dd:d9:dd:c25:c25:e051:1e0/1272c19:dd:d9:dd:c25:c25:e051:1e1
2422c19:dd:d9:dd:c25:c25:e051:1e2/1272c19:dd:d9:dd:c25:c25:e051:1e3
2432c19:dd:d9:dd:c25:c25:e051:1e4/1272c19:dd:d9:dd:c25:c25:e051:1e5
2442c19:dd:d9:dd:c25:c25:e051:1e6/1272c19:dd:d9:dd:c25:c25:e051:1e7
2452c19:dd:d9:dd:c25:c25:e051:1e8/1272c19:dd:d9:dd:c25:c25:e051:1e9
2462c19:dd:d9:dd:c25:c25:e051:1ea/1272c19:dd:d9:dd:c25:c25:e051:1eb
2472c19:dd:d9:dd:c25:c25:e051:1ec/1272c19:dd:d9:dd:c25:c25:e051:1ed
2482c19:dd:d9:dd:c25:c25:e051:1ee/1272c19:dd:d9:dd:c25:c25:e051:1ef
2492c19:dd:d9:dd:c25:c25:e051:1f0/1272c19:dd:d9:dd:c25:c25:e051:1f1
2502c19:dd:d9:dd:c25:c25:e051:1f2/1272c19:dd:d9:dd:c25:c25:e051:1f3
2512c19:dd:d9:dd:c25:c25:e051:1f4/1272c19:dd:d9:dd:c25:c25:e051:1f5
2522c19:dd:d9:dd:c25:c25:e051:1f6/1272c19:dd:d9:dd:c25:c25:e051:1f7
2532c19:dd:d9:dd:c25:c25:e051:1f8/1272c19:dd:d9:dd:c25:c25:e051:1f9
2542c19:dd:d9:dd:c25:c25:e051:1fa/1272c19:dd:d9:dd:c25:c25:e051:1fb
2552c19:dd:d9:dd:c25:c25:e051:1fc/1272c19:dd:d9:dd:c25:c25:e051:1fd
2562c19:dd:d9:dd:c25:c25:e051:1fe/1272c19:dd:d9:dd:c25:c25:e051:1ff

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.