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:dd74:5000/116
First address
2c19:dd:d9:dd:c25:c25:dd74:5000
Last address
2c19:dd:d9:dd:c25:c25:dd74:5fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:dd74:5000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
5.4.7.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/127
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2c19:dd:d9:dd:c25:c25:dd74:5000/116 makes 2,048 subnets of /127; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:dd74:5000/1272c19:dd:d9:dd:c25:c25:dd74:5001
22c19:dd:d9:dd:c25:c25:dd74:5002/1272c19:dd:d9:dd:c25:c25:dd74:5003
32c19:dd:d9:dd:c25:c25:dd74:5004/1272c19:dd:d9:dd:c25:c25:dd74:5005
42c19:dd:d9:dd:c25:c25:dd74:5006/1272c19:dd:d9:dd:c25:c25:dd74:5007
52c19:dd:d9:dd:c25:c25:dd74:5008/1272c19:dd:d9:dd:c25:c25:dd74:5009
62c19:dd:d9:dd:c25:c25:dd74:500a/1272c19:dd:d9:dd:c25:c25:dd74:500b
72c19:dd:d9:dd:c25:c25:dd74:500c/1272c19:dd:d9:dd:c25:c25:dd74:500d
82c19:dd:d9:dd:c25:c25:dd74:500e/1272c19:dd:d9:dd:c25:c25:dd74:500f
92c19:dd:d9:dd:c25:c25:dd74:5010/1272c19:dd:d9:dd:c25:c25:dd74:5011
102c19:dd:d9:dd:c25:c25:dd74:5012/1272c19:dd:d9:dd:c25:c25:dd74:5013
112c19:dd:d9:dd:c25:c25:dd74:5014/1272c19:dd:d9:dd:c25:c25:dd74:5015
122c19:dd:d9:dd:c25:c25:dd74:5016/1272c19:dd:d9:dd:c25:c25:dd74:5017
132c19:dd:d9:dd:c25:c25:dd74:5018/1272c19:dd:d9:dd:c25:c25:dd74:5019
142c19:dd:d9:dd:c25:c25:dd74:501a/1272c19:dd:d9:dd:c25:c25:dd74:501b
152c19:dd:d9:dd:c25:c25:dd74:501c/1272c19:dd:d9:dd:c25:c25:dd74:501d
162c19:dd:d9:dd:c25:c25:dd74:501e/1272c19:dd:d9:dd:c25:c25:dd74:501f
172c19:dd:d9:dd:c25:c25:dd74:5020/1272c19:dd:d9:dd:c25:c25:dd74:5021
182c19:dd:d9:dd:c25:c25:dd74:5022/1272c19:dd:d9:dd:c25:c25:dd74:5023
192c19:dd:d9:dd:c25:c25:dd74:5024/1272c19:dd:d9:dd:c25:c25:dd74:5025
202c19:dd:d9:dd:c25:c25:dd74:5026/1272c19:dd:d9:dd:c25:c25:dd74:5027
212c19:dd:d9:dd:c25:c25:dd74:5028/1272c19:dd:d9:dd:c25:c25:dd74:5029
222c19:dd:d9:dd:c25:c25:dd74:502a/1272c19:dd:d9:dd:c25:c25:dd74:502b
232c19:dd:d9:dd:c25:c25:dd74:502c/1272c19:dd:d9:dd:c25:c25:dd74:502d
242c19:dd:d9:dd:c25:c25:dd74:502e/1272c19:dd:d9:dd:c25:c25:dd74:502f
252c19:dd:d9:dd:c25:c25:dd74:5030/1272c19:dd:d9:dd:c25:c25:dd74:5031
262c19:dd:d9:dd:c25:c25:dd74:5032/1272c19:dd:d9:dd:c25:c25:dd74:5033
272c19:dd:d9:dd:c25:c25:dd74:5034/1272c19:dd:d9:dd:c25:c25:dd74:5035
282c19:dd:d9:dd:c25:c25:dd74:5036/1272c19:dd:d9:dd:c25:c25:dd74:5037
292c19:dd:d9:dd:c25:c25:dd74:5038/1272c19:dd:d9:dd:c25:c25:dd74:5039
302c19:dd:d9:dd:c25:c25:dd74:503a/1272c19:dd:d9:dd:c25:c25:dd74:503b
312c19:dd:d9:dd:c25:c25:dd74:503c/1272c19:dd:d9:dd:c25:c25:dd74:503d
322c19:dd:d9:dd:c25:c25:dd74:503e/1272c19:dd:d9:dd:c25:c25:dd74:503f
332c19:dd:d9:dd:c25:c25:dd74:5040/1272c19:dd:d9:dd:c25:c25:dd74:5041
342c19:dd:d9:dd:c25:c25:dd74:5042/1272c19:dd:d9:dd:c25:c25:dd74:5043
352c19:dd:d9:dd:c25:c25:dd74:5044/1272c19:dd:d9:dd:c25:c25:dd74:5045
362c19:dd:d9:dd:c25:c25:dd74:5046/1272c19:dd:d9:dd:c25:c25:dd74:5047
372c19:dd:d9:dd:c25:c25:dd74:5048/1272c19:dd:d9:dd:c25:c25:dd74:5049
382c19:dd:d9:dd:c25:c25:dd74:504a/1272c19:dd:d9:dd:c25:c25:dd74:504b
392c19:dd:d9:dd:c25:c25:dd74:504c/1272c19:dd:d9:dd:c25:c25:dd74:504d
402c19:dd:d9:dd:c25:c25:dd74:504e/1272c19:dd:d9:dd:c25:c25:dd74:504f
412c19:dd:d9:dd:c25:c25:dd74:5050/1272c19:dd:d9:dd:c25:c25:dd74:5051
422c19:dd:d9:dd:c25:c25:dd74:5052/1272c19:dd:d9:dd:c25:c25:dd74:5053
432c19:dd:d9:dd:c25:c25:dd74:5054/1272c19:dd:d9:dd:c25:c25:dd74:5055
442c19:dd:d9:dd:c25:c25:dd74:5056/1272c19:dd:d9:dd:c25:c25:dd74:5057
452c19:dd:d9:dd:c25:c25:dd74:5058/1272c19:dd:d9:dd:c25:c25:dd74:5059
462c19:dd:d9:dd:c25:c25:dd74:505a/1272c19:dd:d9:dd:c25:c25:dd74:505b
472c19:dd:d9:dd:c25:c25:dd74:505c/1272c19:dd:d9:dd:c25:c25:dd74:505d
482c19:dd:d9:dd:c25:c25:dd74:505e/1272c19:dd:d9:dd:c25:c25:dd74:505f
492c19:dd:d9:dd:c25:c25:dd74:5060/1272c19:dd:d9:dd:c25:c25:dd74:5061
502c19:dd:d9:dd:c25:c25:dd74:5062/1272c19:dd:d9:dd:c25:c25:dd74:5063
512c19:dd:d9:dd:c25:c25:dd74:5064/1272c19:dd:d9:dd:c25:c25:dd74:5065
522c19:dd:d9:dd:c25:c25:dd74:5066/1272c19:dd:d9:dd:c25:c25:dd74:5067
532c19:dd:d9:dd:c25:c25:dd74:5068/1272c19:dd:d9:dd:c25:c25:dd74:5069
542c19:dd:d9:dd:c25:c25:dd74:506a/1272c19:dd:d9:dd:c25:c25:dd74:506b
552c19:dd:d9:dd:c25:c25:dd74:506c/1272c19:dd:d9:dd:c25:c25:dd74:506d
562c19:dd:d9:dd:c25:c25:dd74:506e/1272c19:dd:d9:dd:c25:c25:dd74:506f
572c19:dd:d9:dd:c25:c25:dd74:5070/1272c19:dd:d9:dd:c25:c25:dd74:5071
582c19:dd:d9:dd:c25:c25:dd74:5072/1272c19:dd:d9:dd:c25:c25:dd74:5073
592c19:dd:d9:dd:c25:c25:dd74:5074/1272c19:dd:d9:dd:c25:c25:dd74:5075
602c19:dd:d9:dd:c25:c25:dd74:5076/1272c19:dd:d9:dd:c25:c25:dd74:5077
612c19:dd:d9:dd:c25:c25:dd74:5078/1272c19:dd:d9:dd:c25:c25:dd74:5079
622c19:dd:d9:dd:c25:c25:dd74:507a/1272c19:dd:d9:dd:c25:c25:dd74:507b
632c19:dd:d9:dd:c25:c25:dd74:507c/1272c19:dd:d9:dd:c25:c25:dd74:507d
642c19:dd:d9:dd:c25:c25:dd74:507e/1272c19:dd:d9:dd:c25:c25:dd74:507f
652c19:dd:d9:dd:c25:c25:dd74:5080/1272c19:dd:d9:dd:c25:c25:dd74:5081
662c19:dd:d9:dd:c25:c25:dd74:5082/1272c19:dd:d9:dd:c25:c25:dd74:5083
672c19:dd:d9:dd:c25:c25:dd74:5084/1272c19:dd:d9:dd:c25:c25:dd74:5085
682c19:dd:d9:dd:c25:c25:dd74:5086/1272c19:dd:d9:dd:c25:c25:dd74:5087
692c19:dd:d9:dd:c25:c25:dd74:5088/1272c19:dd:d9:dd:c25:c25:dd74:5089
702c19:dd:d9:dd:c25:c25:dd74:508a/1272c19:dd:d9:dd:c25:c25:dd74:508b
712c19:dd:d9:dd:c25:c25:dd74:508c/1272c19:dd:d9:dd:c25:c25:dd74:508d
722c19:dd:d9:dd:c25:c25:dd74:508e/1272c19:dd:d9:dd:c25:c25:dd74:508f
732c19:dd:d9:dd:c25:c25:dd74:5090/1272c19:dd:d9:dd:c25:c25:dd74:5091
742c19:dd:d9:dd:c25:c25:dd74:5092/1272c19:dd:d9:dd:c25:c25:dd74:5093
752c19:dd:d9:dd:c25:c25:dd74:5094/1272c19:dd:d9:dd:c25:c25:dd74:5095
762c19:dd:d9:dd:c25:c25:dd74:5096/1272c19:dd:d9:dd:c25:c25:dd74:5097
772c19:dd:d9:dd:c25:c25:dd74:5098/1272c19:dd:d9:dd:c25:c25:dd74:5099
782c19:dd:d9:dd:c25:c25:dd74:509a/1272c19:dd:d9:dd:c25:c25:dd74:509b
792c19:dd:d9:dd:c25:c25:dd74:509c/1272c19:dd:d9:dd:c25:c25:dd74:509d
802c19:dd:d9:dd:c25:c25:dd74:509e/1272c19:dd:d9:dd:c25:c25:dd74:509f
812c19:dd:d9:dd:c25:c25:dd74:50a0/1272c19:dd:d9:dd:c25:c25:dd74:50a1
822c19:dd:d9:dd:c25:c25:dd74:50a2/1272c19:dd:d9:dd:c25:c25:dd74:50a3
832c19:dd:d9:dd:c25:c25:dd74:50a4/1272c19:dd:d9:dd:c25:c25:dd74:50a5
842c19:dd:d9:dd:c25:c25:dd74:50a6/1272c19:dd:d9:dd:c25:c25:dd74:50a7
852c19:dd:d9:dd:c25:c25:dd74:50a8/1272c19:dd:d9:dd:c25:c25:dd74:50a9
862c19:dd:d9:dd:c25:c25:dd74:50aa/1272c19:dd:d9:dd:c25:c25:dd74:50ab
872c19:dd:d9:dd:c25:c25:dd74:50ac/1272c19:dd:d9:dd:c25:c25:dd74:50ad
882c19:dd:d9:dd:c25:c25:dd74:50ae/1272c19:dd:d9:dd:c25:c25:dd74:50af
892c19:dd:d9:dd:c25:c25:dd74:50b0/1272c19:dd:d9:dd:c25:c25:dd74:50b1
902c19:dd:d9:dd:c25:c25:dd74:50b2/1272c19:dd:d9:dd:c25:c25:dd74:50b3
912c19:dd:d9:dd:c25:c25:dd74:50b4/1272c19:dd:d9:dd:c25:c25:dd74:50b5
922c19:dd:d9:dd:c25:c25:dd74:50b6/1272c19:dd:d9:dd:c25:c25:dd74:50b7
932c19:dd:d9:dd:c25:c25:dd74:50b8/1272c19:dd:d9:dd:c25:c25:dd74:50b9
942c19:dd:d9:dd:c25:c25:dd74:50ba/1272c19:dd:d9:dd:c25:c25:dd74:50bb
952c19:dd:d9:dd:c25:c25:dd74:50bc/1272c19:dd:d9:dd:c25:c25:dd74:50bd
962c19:dd:d9:dd:c25:c25:dd74:50be/1272c19:dd:d9:dd:c25:c25:dd74:50bf
972c19:dd:d9:dd:c25:c25:dd74:50c0/1272c19:dd:d9:dd:c25:c25:dd74:50c1
982c19:dd:d9:dd:c25:c25:dd74:50c2/1272c19:dd:d9:dd:c25:c25:dd74:50c3
992c19:dd:d9:dd:c25:c25:dd74:50c4/1272c19:dd:d9:dd:c25:c25:dd74:50c5
1002c19:dd:d9:dd:c25:c25:dd74:50c6/1272c19:dd:d9:dd:c25:c25:dd74:50c7
1012c19:dd:d9:dd:c25:c25:dd74:50c8/1272c19:dd:d9:dd:c25:c25:dd74:50c9
1022c19:dd:d9:dd:c25:c25:dd74:50ca/1272c19:dd:d9:dd:c25:c25:dd74:50cb
1032c19:dd:d9:dd:c25:c25:dd74:50cc/1272c19:dd:d9:dd:c25:c25:dd74:50cd
1042c19:dd:d9:dd:c25:c25:dd74:50ce/1272c19:dd:d9:dd:c25:c25:dd74:50cf
1052c19:dd:d9:dd:c25:c25:dd74:50d0/1272c19:dd:d9:dd:c25:c25:dd74:50d1
1062c19:dd:d9:dd:c25:c25:dd74:50d2/1272c19:dd:d9:dd:c25:c25:dd74:50d3
1072c19:dd:d9:dd:c25:c25:dd74:50d4/1272c19:dd:d9:dd:c25:c25:dd74:50d5
1082c19:dd:d9:dd:c25:c25:dd74:50d6/1272c19:dd:d9:dd:c25:c25:dd74:50d7
1092c19:dd:d9:dd:c25:c25:dd74:50d8/1272c19:dd:d9:dd:c25:c25:dd74:50d9
1102c19:dd:d9:dd:c25:c25:dd74:50da/1272c19:dd:d9:dd:c25:c25:dd74:50db
1112c19:dd:d9:dd:c25:c25:dd74:50dc/1272c19:dd:d9:dd:c25:c25:dd74:50dd
1122c19:dd:d9:dd:c25:c25:dd74:50de/1272c19:dd:d9:dd:c25:c25:dd74:50df
1132c19:dd:d9:dd:c25:c25:dd74:50e0/1272c19:dd:d9:dd:c25:c25:dd74:50e1
1142c19:dd:d9:dd:c25:c25:dd74:50e2/1272c19:dd:d9:dd:c25:c25:dd74:50e3
1152c19:dd:d9:dd:c25:c25:dd74:50e4/1272c19:dd:d9:dd:c25:c25:dd74:50e5
1162c19:dd:d9:dd:c25:c25:dd74:50e6/1272c19:dd:d9:dd:c25:c25:dd74:50e7
1172c19:dd:d9:dd:c25:c25:dd74:50e8/1272c19:dd:d9:dd:c25:c25:dd74:50e9
1182c19:dd:d9:dd:c25:c25:dd74:50ea/1272c19:dd:d9:dd:c25:c25:dd74:50eb
1192c19:dd:d9:dd:c25:c25:dd74:50ec/1272c19:dd:d9:dd:c25:c25:dd74:50ed
1202c19:dd:d9:dd:c25:c25:dd74:50ee/1272c19:dd:d9:dd:c25:c25:dd74:50ef
1212c19:dd:d9:dd:c25:c25:dd74:50f0/1272c19:dd:d9:dd:c25:c25:dd74:50f1
1222c19:dd:d9:dd:c25:c25:dd74:50f2/1272c19:dd:d9:dd:c25:c25:dd74:50f3
1232c19:dd:d9:dd:c25:c25:dd74:50f4/1272c19:dd:d9:dd:c25:c25:dd74:50f5
1242c19:dd:d9:dd:c25:c25:dd74:50f6/1272c19:dd:d9:dd:c25:c25:dd74:50f7
1252c19:dd:d9:dd:c25:c25:dd74:50f8/1272c19:dd:d9:dd:c25:c25:dd74:50f9
1262c19:dd:d9:dd:c25:c25:dd74:50fa/1272c19:dd:d9:dd:c25:c25:dd74:50fb
1272c19:dd:d9:dd:c25:c25:dd74:50fc/1272c19:dd:d9:dd:c25:c25:dd74:50fd
1282c19:dd:d9:dd:c25:c25:dd74:50fe/1272c19:dd:d9:dd:c25:c25:dd74:50ff
1292c19:dd:d9:dd:c25:c25:dd74:5100/1272c19:dd:d9:dd:c25:c25:dd74:5101
1302c19:dd:d9:dd:c25:c25:dd74:5102/1272c19:dd:d9:dd:c25:c25:dd74:5103
1312c19:dd:d9:dd:c25:c25:dd74:5104/1272c19:dd:d9:dd:c25:c25:dd74:5105
1322c19:dd:d9:dd:c25:c25:dd74:5106/1272c19:dd:d9:dd:c25:c25:dd74:5107
1332c19:dd:d9:dd:c25:c25:dd74:5108/1272c19:dd:d9:dd:c25:c25:dd74:5109
1342c19:dd:d9:dd:c25:c25:dd74:510a/1272c19:dd:d9:dd:c25:c25:dd74:510b
1352c19:dd:d9:dd:c25:c25:dd74:510c/1272c19:dd:d9:dd:c25:c25:dd74:510d
1362c19:dd:d9:dd:c25:c25:dd74:510e/1272c19:dd:d9:dd:c25:c25:dd74:510f
1372c19:dd:d9:dd:c25:c25:dd74:5110/1272c19:dd:d9:dd:c25:c25:dd74:5111
1382c19:dd:d9:dd:c25:c25:dd74:5112/1272c19:dd:d9:dd:c25:c25:dd74:5113
1392c19:dd:d9:dd:c25:c25:dd74:5114/1272c19:dd:d9:dd:c25:c25:dd74:5115
1402c19:dd:d9:dd:c25:c25:dd74:5116/1272c19:dd:d9:dd:c25:c25:dd74:5117
1412c19:dd:d9:dd:c25:c25:dd74:5118/1272c19:dd:d9:dd:c25:c25:dd74:5119
1422c19:dd:d9:dd:c25:c25:dd74:511a/1272c19:dd:d9:dd:c25:c25:dd74:511b
1432c19:dd:d9:dd:c25:c25:dd74:511c/1272c19:dd:d9:dd:c25:c25:dd74:511d
1442c19:dd:d9:dd:c25:c25:dd74:511e/1272c19:dd:d9:dd:c25:c25:dd74:511f
1452c19:dd:d9:dd:c25:c25:dd74:5120/1272c19:dd:d9:dd:c25:c25:dd74:5121
1462c19:dd:d9:dd:c25:c25:dd74:5122/1272c19:dd:d9:dd:c25:c25:dd74:5123
1472c19:dd:d9:dd:c25:c25:dd74:5124/1272c19:dd:d9:dd:c25:c25:dd74:5125
1482c19:dd:d9:dd:c25:c25:dd74:5126/1272c19:dd:d9:dd:c25:c25:dd74:5127
1492c19:dd:d9:dd:c25:c25:dd74:5128/1272c19:dd:d9:dd:c25:c25:dd74:5129
1502c19:dd:d9:dd:c25:c25:dd74:512a/1272c19:dd:d9:dd:c25:c25:dd74:512b
1512c19:dd:d9:dd:c25:c25:dd74:512c/1272c19:dd:d9:dd:c25:c25:dd74:512d
1522c19:dd:d9:dd:c25:c25:dd74:512e/1272c19:dd:d9:dd:c25:c25:dd74:512f
1532c19:dd:d9:dd:c25:c25:dd74:5130/1272c19:dd:d9:dd:c25:c25:dd74:5131
1542c19:dd:d9:dd:c25:c25:dd74:5132/1272c19:dd:d9:dd:c25:c25:dd74:5133
1552c19:dd:d9:dd:c25:c25:dd74:5134/1272c19:dd:d9:dd:c25:c25:dd74:5135
1562c19:dd:d9:dd:c25:c25:dd74:5136/1272c19:dd:d9:dd:c25:c25:dd74:5137
1572c19:dd:d9:dd:c25:c25:dd74:5138/1272c19:dd:d9:dd:c25:c25:dd74:5139
1582c19:dd:d9:dd:c25:c25:dd74:513a/1272c19:dd:d9:dd:c25:c25:dd74:513b
1592c19:dd:d9:dd:c25:c25:dd74:513c/1272c19:dd:d9:dd:c25:c25:dd74:513d
1602c19:dd:d9:dd:c25:c25:dd74:513e/1272c19:dd:d9:dd:c25:c25:dd74:513f
1612c19:dd:d9:dd:c25:c25:dd74:5140/1272c19:dd:d9:dd:c25:c25:dd74:5141
1622c19:dd:d9:dd:c25:c25:dd74:5142/1272c19:dd:d9:dd:c25:c25:dd74:5143
1632c19:dd:d9:dd:c25:c25:dd74:5144/1272c19:dd:d9:dd:c25:c25:dd74:5145
1642c19:dd:d9:dd:c25:c25:dd74:5146/1272c19:dd:d9:dd:c25:c25:dd74:5147
1652c19:dd:d9:dd:c25:c25:dd74:5148/1272c19:dd:d9:dd:c25:c25:dd74:5149
1662c19:dd:d9:dd:c25:c25:dd74:514a/1272c19:dd:d9:dd:c25:c25:dd74:514b
1672c19:dd:d9:dd:c25:c25:dd74:514c/1272c19:dd:d9:dd:c25:c25:dd74:514d
1682c19:dd:d9:dd:c25:c25:dd74:514e/1272c19:dd:d9:dd:c25:c25:dd74:514f
1692c19:dd:d9:dd:c25:c25:dd74:5150/1272c19:dd:d9:dd:c25:c25:dd74:5151
1702c19:dd:d9:dd:c25:c25:dd74:5152/1272c19:dd:d9:dd:c25:c25:dd74:5153
1712c19:dd:d9:dd:c25:c25:dd74:5154/1272c19:dd:d9:dd:c25:c25:dd74:5155
1722c19:dd:d9:dd:c25:c25:dd74:5156/1272c19:dd:d9:dd:c25:c25:dd74:5157
1732c19:dd:d9:dd:c25:c25:dd74:5158/1272c19:dd:d9:dd:c25:c25:dd74:5159
1742c19:dd:d9:dd:c25:c25:dd74:515a/1272c19:dd:d9:dd:c25:c25:dd74:515b
1752c19:dd:d9:dd:c25:c25:dd74:515c/1272c19:dd:d9:dd:c25:c25:dd74:515d
1762c19:dd:d9:dd:c25:c25:dd74:515e/1272c19:dd:d9:dd:c25:c25:dd74:515f
1772c19:dd:d9:dd:c25:c25:dd74:5160/1272c19:dd:d9:dd:c25:c25:dd74:5161
1782c19:dd:d9:dd:c25:c25:dd74:5162/1272c19:dd:d9:dd:c25:c25:dd74:5163
1792c19:dd:d9:dd:c25:c25:dd74:5164/1272c19:dd:d9:dd:c25:c25:dd74:5165
1802c19:dd:d9:dd:c25:c25:dd74:5166/1272c19:dd:d9:dd:c25:c25:dd74:5167
1812c19:dd:d9:dd:c25:c25:dd74:5168/1272c19:dd:d9:dd:c25:c25:dd74:5169
1822c19:dd:d9:dd:c25:c25:dd74:516a/1272c19:dd:d9:dd:c25:c25:dd74:516b
1832c19:dd:d9:dd:c25:c25:dd74:516c/1272c19:dd:d9:dd:c25:c25:dd74:516d
1842c19:dd:d9:dd:c25:c25:dd74:516e/1272c19:dd:d9:dd:c25:c25:dd74:516f
1852c19:dd:d9:dd:c25:c25:dd74:5170/1272c19:dd:d9:dd:c25:c25:dd74:5171
1862c19:dd:d9:dd:c25:c25:dd74:5172/1272c19:dd:d9:dd:c25:c25:dd74:5173
1872c19:dd:d9:dd:c25:c25:dd74:5174/1272c19:dd:d9:dd:c25:c25:dd74:5175
1882c19:dd:d9:dd:c25:c25:dd74:5176/1272c19:dd:d9:dd:c25:c25:dd74:5177
1892c19:dd:d9:dd:c25:c25:dd74:5178/1272c19:dd:d9:dd:c25:c25:dd74:5179
1902c19:dd:d9:dd:c25:c25:dd74:517a/1272c19:dd:d9:dd:c25:c25:dd74:517b
1912c19:dd:d9:dd:c25:c25:dd74:517c/1272c19:dd:d9:dd:c25:c25:dd74:517d
1922c19:dd:d9:dd:c25:c25:dd74:517e/1272c19:dd:d9:dd:c25:c25:dd74:517f
1932c19:dd:d9:dd:c25:c25:dd74:5180/1272c19:dd:d9:dd:c25:c25:dd74:5181
1942c19:dd:d9:dd:c25:c25:dd74:5182/1272c19:dd:d9:dd:c25:c25:dd74:5183
1952c19:dd:d9:dd:c25:c25:dd74:5184/1272c19:dd:d9:dd:c25:c25:dd74:5185
1962c19:dd:d9:dd:c25:c25:dd74:5186/1272c19:dd:d9:dd:c25:c25:dd74:5187
1972c19:dd:d9:dd:c25:c25:dd74:5188/1272c19:dd:d9:dd:c25:c25:dd74:5189
1982c19:dd:d9:dd:c25:c25:dd74:518a/1272c19:dd:d9:dd:c25:c25:dd74:518b
1992c19:dd:d9:dd:c25:c25:dd74:518c/1272c19:dd:d9:dd:c25:c25:dd74:518d
2002c19:dd:d9:dd:c25:c25:dd74:518e/1272c19:dd:d9:dd:c25:c25:dd74:518f
2012c19:dd:d9:dd:c25:c25:dd74:5190/1272c19:dd:d9:dd:c25:c25:dd74:5191
2022c19:dd:d9:dd:c25:c25:dd74:5192/1272c19:dd:d9:dd:c25:c25:dd74:5193
2032c19:dd:d9:dd:c25:c25:dd74:5194/1272c19:dd:d9:dd:c25:c25:dd74:5195
2042c19:dd:d9:dd:c25:c25:dd74:5196/1272c19:dd:d9:dd:c25:c25:dd74:5197
2052c19:dd:d9:dd:c25:c25:dd74:5198/1272c19:dd:d9:dd:c25:c25:dd74:5199
2062c19:dd:d9:dd:c25:c25:dd74:519a/1272c19:dd:d9:dd:c25:c25:dd74:519b
2072c19:dd:d9:dd:c25:c25:dd74:519c/1272c19:dd:d9:dd:c25:c25:dd74:519d
2082c19:dd:d9:dd:c25:c25:dd74:519e/1272c19:dd:d9:dd:c25:c25:dd74:519f
2092c19:dd:d9:dd:c25:c25:dd74:51a0/1272c19:dd:d9:dd:c25:c25:dd74:51a1
2102c19:dd:d9:dd:c25:c25:dd74:51a2/1272c19:dd:d9:dd:c25:c25:dd74:51a3
2112c19:dd:d9:dd:c25:c25:dd74:51a4/1272c19:dd:d9:dd:c25:c25:dd74:51a5
2122c19:dd:d9:dd:c25:c25:dd74:51a6/1272c19:dd:d9:dd:c25:c25:dd74:51a7
2132c19:dd:d9:dd:c25:c25:dd74:51a8/1272c19:dd:d9:dd:c25:c25:dd74:51a9
2142c19:dd:d9:dd:c25:c25:dd74:51aa/1272c19:dd:d9:dd:c25:c25:dd74:51ab
2152c19:dd:d9:dd:c25:c25:dd74:51ac/1272c19:dd:d9:dd:c25:c25:dd74:51ad
2162c19:dd:d9:dd:c25:c25:dd74:51ae/1272c19:dd:d9:dd:c25:c25:dd74:51af
2172c19:dd:d9:dd:c25:c25:dd74:51b0/1272c19:dd:d9:dd:c25:c25:dd74:51b1
2182c19:dd:d9:dd:c25:c25:dd74:51b2/1272c19:dd:d9:dd:c25:c25:dd74:51b3
2192c19:dd:d9:dd:c25:c25:dd74:51b4/1272c19:dd:d9:dd:c25:c25:dd74:51b5
2202c19:dd:d9:dd:c25:c25:dd74:51b6/1272c19:dd:d9:dd:c25:c25:dd74:51b7
2212c19:dd:d9:dd:c25:c25:dd74:51b8/1272c19:dd:d9:dd:c25:c25:dd74:51b9
2222c19:dd:d9:dd:c25:c25:dd74:51ba/1272c19:dd:d9:dd:c25:c25:dd74:51bb
2232c19:dd:d9:dd:c25:c25:dd74:51bc/1272c19:dd:d9:dd:c25:c25:dd74:51bd
2242c19:dd:d9:dd:c25:c25:dd74:51be/1272c19:dd:d9:dd:c25:c25:dd74:51bf
2252c19:dd:d9:dd:c25:c25:dd74:51c0/1272c19:dd:d9:dd:c25:c25:dd74:51c1
2262c19:dd:d9:dd:c25:c25:dd74:51c2/1272c19:dd:d9:dd:c25:c25:dd74:51c3
2272c19:dd:d9:dd:c25:c25:dd74:51c4/1272c19:dd:d9:dd:c25:c25:dd74:51c5
2282c19:dd:d9:dd:c25:c25:dd74:51c6/1272c19:dd:d9:dd:c25:c25:dd74:51c7
2292c19:dd:d9:dd:c25:c25:dd74:51c8/1272c19:dd:d9:dd:c25:c25:dd74:51c9
2302c19:dd:d9:dd:c25:c25:dd74:51ca/1272c19:dd:d9:dd:c25:c25:dd74:51cb
2312c19:dd:d9:dd:c25:c25:dd74:51cc/1272c19:dd:d9:dd:c25:c25:dd74:51cd
2322c19:dd:d9:dd:c25:c25:dd74:51ce/1272c19:dd:d9:dd:c25:c25:dd74:51cf
2332c19:dd:d9:dd:c25:c25:dd74:51d0/1272c19:dd:d9:dd:c25:c25:dd74:51d1
2342c19:dd:d9:dd:c25:c25:dd74:51d2/1272c19:dd:d9:dd:c25:c25:dd74:51d3
2352c19:dd:d9:dd:c25:c25:dd74:51d4/1272c19:dd:d9:dd:c25:c25:dd74:51d5
2362c19:dd:d9:dd:c25:c25:dd74:51d6/1272c19:dd:d9:dd:c25:c25:dd74:51d7
2372c19:dd:d9:dd:c25:c25:dd74:51d8/1272c19:dd:d9:dd:c25:c25:dd74:51d9
2382c19:dd:d9:dd:c25:c25:dd74:51da/1272c19:dd:d9:dd:c25:c25:dd74:51db
2392c19:dd:d9:dd:c25:c25:dd74:51dc/1272c19:dd:d9:dd:c25:c25:dd74:51dd
2402c19:dd:d9:dd:c25:c25:dd74:51de/1272c19:dd:d9:dd:c25:c25:dd74:51df
2412c19:dd:d9:dd:c25:c25:dd74:51e0/1272c19:dd:d9:dd:c25:c25:dd74:51e1
2422c19:dd:d9:dd:c25:c25:dd74:51e2/1272c19:dd:d9:dd:c25:c25:dd74:51e3
2432c19:dd:d9:dd:c25:c25:dd74:51e4/1272c19:dd:d9:dd:c25:c25:dd74:51e5
2442c19:dd:d9:dd:c25:c25:dd74:51e6/1272c19:dd:d9:dd:c25:c25:dd74:51e7
2452c19:dd:d9:dd:c25:c25:dd74:51e8/1272c19:dd:d9:dd:c25:c25:dd74:51e9
2462c19:dd:d9:dd:c25:c25:dd74:51ea/1272c19:dd:d9:dd:c25:c25:dd74:51eb
2472c19:dd:d9:dd:c25:c25:dd74:51ec/1272c19:dd:d9:dd:c25:c25:dd74:51ed
2482c19:dd:d9:dd:c25:c25:dd74:51ee/1272c19:dd:d9:dd:c25:c25:dd74:51ef
2492c19:dd:d9:dd:c25:c25:dd74:51f0/1272c19:dd:d9:dd:c25:c25:dd74:51f1
2502c19:dd:d9:dd:c25:c25:dd74:51f2/1272c19:dd:d9:dd:c25:c25:dd74:51f3
2512c19:dd:d9:dd:c25:c25:dd74:51f4/1272c19:dd:d9:dd:c25:c25:dd74:51f5
2522c19:dd:d9:dd:c25:c25:dd74:51f6/1272c19:dd:d9:dd:c25:c25:dd74:51f7
2532c19:dd:d9:dd:c25:c25:dd74:51f8/1272c19:dd:d9:dd:c25:c25:dd74:51f9
2542c19:dd:d9:dd:c25:c25:dd74:51fa/1272c19:dd:d9:dd:c25:c25:dd74:51fb
2552c19:dd:d9:dd:c25:c25:dd74:51fc/1272c19:dd:d9:dd:c25:c25:dd74:51fd
2562c19:dd:d9:dd:c25:c25:dd74:51fe/1272c19:dd:d9:dd:c25:c25:dd74:51ff

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.