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:c25:1:7000/116
First address
2c19:dd:d9:dd:c25:c25:1:7000
Last address
2c19:dd:d9:dd:c25:c25:1:7fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:0001:7000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
7.1.0.0.0.5.2.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:c25:1:7000/116 makes 2,048 subnets of /127; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:1:7000/1272c19:dd:d9:dd:c25:c25:1:7001
22c19:dd:d9:dd:c25:c25:1:7002/1272c19:dd:d9:dd:c25:c25:1:7003
32c19:dd:d9:dd:c25:c25:1:7004/1272c19:dd:d9:dd:c25:c25:1:7005
42c19:dd:d9:dd:c25:c25:1:7006/1272c19:dd:d9:dd:c25:c25:1:7007
52c19:dd:d9:dd:c25:c25:1:7008/1272c19:dd:d9:dd:c25:c25:1:7009
62c19:dd:d9:dd:c25:c25:1:700a/1272c19:dd:d9:dd:c25:c25:1:700b
72c19:dd:d9:dd:c25:c25:1:700c/1272c19:dd:d9:dd:c25:c25:1:700d
82c19:dd:d9:dd:c25:c25:1:700e/1272c19:dd:d9:dd:c25:c25:1:700f
92c19:dd:d9:dd:c25:c25:1:7010/1272c19:dd:d9:dd:c25:c25:1:7011
102c19:dd:d9:dd:c25:c25:1:7012/1272c19:dd:d9:dd:c25:c25:1:7013
112c19:dd:d9:dd:c25:c25:1:7014/1272c19:dd:d9:dd:c25:c25:1:7015
122c19:dd:d9:dd:c25:c25:1:7016/1272c19:dd:d9:dd:c25:c25:1:7017
132c19:dd:d9:dd:c25:c25:1:7018/1272c19:dd:d9:dd:c25:c25:1:7019
142c19:dd:d9:dd:c25:c25:1:701a/1272c19:dd:d9:dd:c25:c25:1:701b
152c19:dd:d9:dd:c25:c25:1:701c/1272c19:dd:d9:dd:c25:c25:1:701d
162c19:dd:d9:dd:c25:c25:1:701e/1272c19:dd:d9:dd:c25:c25:1:701f
172c19:dd:d9:dd:c25:c25:1:7020/1272c19:dd:d9:dd:c25:c25:1:7021
182c19:dd:d9:dd:c25:c25:1:7022/1272c19:dd:d9:dd:c25:c25:1:7023
192c19:dd:d9:dd:c25:c25:1:7024/1272c19:dd:d9:dd:c25:c25:1:7025
202c19:dd:d9:dd:c25:c25:1:7026/1272c19:dd:d9:dd:c25:c25:1:7027
212c19:dd:d9:dd:c25:c25:1:7028/1272c19:dd:d9:dd:c25:c25:1:7029
222c19:dd:d9:dd:c25:c25:1:702a/1272c19:dd:d9:dd:c25:c25:1:702b
232c19:dd:d9:dd:c25:c25:1:702c/1272c19:dd:d9:dd:c25:c25:1:702d
242c19:dd:d9:dd:c25:c25:1:702e/1272c19:dd:d9:dd:c25:c25:1:702f
252c19:dd:d9:dd:c25:c25:1:7030/1272c19:dd:d9:dd:c25:c25:1:7031
262c19:dd:d9:dd:c25:c25:1:7032/1272c19:dd:d9:dd:c25:c25:1:7033
272c19:dd:d9:dd:c25:c25:1:7034/1272c19:dd:d9:dd:c25:c25:1:7035
282c19:dd:d9:dd:c25:c25:1:7036/1272c19:dd:d9:dd:c25:c25:1:7037
292c19:dd:d9:dd:c25:c25:1:7038/1272c19:dd:d9:dd:c25:c25:1:7039
302c19:dd:d9:dd:c25:c25:1:703a/1272c19:dd:d9:dd:c25:c25:1:703b
312c19:dd:d9:dd:c25:c25:1:703c/1272c19:dd:d9:dd:c25:c25:1:703d
322c19:dd:d9:dd:c25:c25:1:703e/1272c19:dd:d9:dd:c25:c25:1:703f
332c19:dd:d9:dd:c25:c25:1:7040/1272c19:dd:d9:dd:c25:c25:1:7041
342c19:dd:d9:dd:c25:c25:1:7042/1272c19:dd:d9:dd:c25:c25:1:7043
352c19:dd:d9:dd:c25:c25:1:7044/1272c19:dd:d9:dd:c25:c25:1:7045
362c19:dd:d9:dd:c25:c25:1:7046/1272c19:dd:d9:dd:c25:c25:1:7047
372c19:dd:d9:dd:c25:c25:1:7048/1272c19:dd:d9:dd:c25:c25:1:7049
382c19:dd:d9:dd:c25:c25:1:704a/1272c19:dd:d9:dd:c25:c25:1:704b
392c19:dd:d9:dd:c25:c25:1:704c/1272c19:dd:d9:dd:c25:c25:1:704d
402c19:dd:d9:dd:c25:c25:1:704e/1272c19:dd:d9:dd:c25:c25:1:704f
412c19:dd:d9:dd:c25:c25:1:7050/1272c19:dd:d9:dd:c25:c25:1:7051
422c19:dd:d9:dd:c25:c25:1:7052/1272c19:dd:d9:dd:c25:c25:1:7053
432c19:dd:d9:dd:c25:c25:1:7054/1272c19:dd:d9:dd:c25:c25:1:7055
442c19:dd:d9:dd:c25:c25:1:7056/1272c19:dd:d9:dd:c25:c25:1:7057
452c19:dd:d9:dd:c25:c25:1:7058/1272c19:dd:d9:dd:c25:c25:1:7059
462c19:dd:d9:dd:c25:c25:1:705a/1272c19:dd:d9:dd:c25:c25:1:705b
472c19:dd:d9:dd:c25:c25:1:705c/1272c19:dd:d9:dd:c25:c25:1:705d
482c19:dd:d9:dd:c25:c25:1:705e/1272c19:dd:d9:dd:c25:c25:1:705f
492c19:dd:d9:dd:c25:c25:1:7060/1272c19:dd:d9:dd:c25:c25:1:7061
502c19:dd:d9:dd:c25:c25:1:7062/1272c19:dd:d9:dd:c25:c25:1:7063
512c19:dd:d9:dd:c25:c25:1:7064/1272c19:dd:d9:dd:c25:c25:1:7065
522c19:dd:d9:dd:c25:c25:1:7066/1272c19:dd:d9:dd:c25:c25:1:7067
532c19:dd:d9:dd:c25:c25:1:7068/1272c19:dd:d9:dd:c25:c25:1:7069
542c19:dd:d9:dd:c25:c25:1:706a/1272c19:dd:d9:dd:c25:c25:1:706b
552c19:dd:d9:dd:c25:c25:1:706c/1272c19:dd:d9:dd:c25:c25:1:706d
562c19:dd:d9:dd:c25:c25:1:706e/1272c19:dd:d9:dd:c25:c25:1:706f
572c19:dd:d9:dd:c25:c25:1:7070/1272c19:dd:d9:dd:c25:c25:1:7071
582c19:dd:d9:dd:c25:c25:1:7072/1272c19:dd:d9:dd:c25:c25:1:7073
592c19:dd:d9:dd:c25:c25:1:7074/1272c19:dd:d9:dd:c25:c25:1:7075
602c19:dd:d9:dd:c25:c25:1:7076/1272c19:dd:d9:dd:c25:c25:1:7077
612c19:dd:d9:dd:c25:c25:1:7078/1272c19:dd:d9:dd:c25:c25:1:7079
622c19:dd:d9:dd:c25:c25:1:707a/1272c19:dd:d9:dd:c25:c25:1:707b
632c19:dd:d9:dd:c25:c25:1:707c/1272c19:dd:d9:dd:c25:c25:1:707d
642c19:dd:d9:dd:c25:c25:1:707e/1272c19:dd:d9:dd:c25:c25:1:707f
652c19:dd:d9:dd:c25:c25:1:7080/1272c19:dd:d9:dd:c25:c25:1:7081
662c19:dd:d9:dd:c25:c25:1:7082/1272c19:dd:d9:dd:c25:c25:1:7083
672c19:dd:d9:dd:c25:c25:1:7084/1272c19:dd:d9:dd:c25:c25:1:7085
682c19:dd:d9:dd:c25:c25:1:7086/1272c19:dd:d9:dd:c25:c25:1:7087
692c19:dd:d9:dd:c25:c25:1:7088/1272c19:dd:d9:dd:c25:c25:1:7089
702c19:dd:d9:dd:c25:c25:1:708a/1272c19:dd:d9:dd:c25:c25:1:708b
712c19:dd:d9:dd:c25:c25:1:708c/1272c19:dd:d9:dd:c25:c25:1:708d
722c19:dd:d9:dd:c25:c25:1:708e/1272c19:dd:d9:dd:c25:c25:1:708f
732c19:dd:d9:dd:c25:c25:1:7090/1272c19:dd:d9:dd:c25:c25:1:7091
742c19:dd:d9:dd:c25:c25:1:7092/1272c19:dd:d9:dd:c25:c25:1:7093
752c19:dd:d9:dd:c25:c25:1:7094/1272c19:dd:d9:dd:c25:c25:1:7095
762c19:dd:d9:dd:c25:c25:1:7096/1272c19:dd:d9:dd:c25:c25:1:7097
772c19:dd:d9:dd:c25:c25:1:7098/1272c19:dd:d9:dd:c25:c25:1:7099
782c19:dd:d9:dd:c25:c25:1:709a/1272c19:dd:d9:dd:c25:c25:1:709b
792c19:dd:d9:dd:c25:c25:1:709c/1272c19:dd:d9:dd:c25:c25:1:709d
802c19:dd:d9:dd:c25:c25:1:709e/1272c19:dd:d9:dd:c25:c25:1:709f
812c19:dd:d9:dd:c25:c25:1:70a0/1272c19:dd:d9:dd:c25:c25:1:70a1
822c19:dd:d9:dd:c25:c25:1:70a2/1272c19:dd:d9:dd:c25:c25:1:70a3
832c19:dd:d9:dd:c25:c25:1:70a4/1272c19:dd:d9:dd:c25:c25:1:70a5
842c19:dd:d9:dd:c25:c25:1:70a6/1272c19:dd:d9:dd:c25:c25:1:70a7
852c19:dd:d9:dd:c25:c25:1:70a8/1272c19:dd:d9:dd:c25:c25:1:70a9
862c19:dd:d9:dd:c25:c25:1:70aa/1272c19:dd:d9:dd:c25:c25:1:70ab
872c19:dd:d9:dd:c25:c25:1:70ac/1272c19:dd:d9:dd:c25:c25:1:70ad
882c19:dd:d9:dd:c25:c25:1:70ae/1272c19:dd:d9:dd:c25:c25:1:70af
892c19:dd:d9:dd:c25:c25:1:70b0/1272c19:dd:d9:dd:c25:c25:1:70b1
902c19:dd:d9:dd:c25:c25:1:70b2/1272c19:dd:d9:dd:c25:c25:1:70b3
912c19:dd:d9:dd:c25:c25:1:70b4/1272c19:dd:d9:dd:c25:c25:1:70b5
922c19:dd:d9:dd:c25:c25:1:70b6/1272c19:dd:d9:dd:c25:c25:1:70b7
932c19:dd:d9:dd:c25:c25:1:70b8/1272c19:dd:d9:dd:c25:c25:1:70b9
942c19:dd:d9:dd:c25:c25:1:70ba/1272c19:dd:d9:dd:c25:c25:1:70bb
952c19:dd:d9:dd:c25:c25:1:70bc/1272c19:dd:d9:dd:c25:c25:1:70bd
962c19:dd:d9:dd:c25:c25:1:70be/1272c19:dd:d9:dd:c25:c25:1:70bf
972c19:dd:d9:dd:c25:c25:1:70c0/1272c19:dd:d9:dd:c25:c25:1:70c1
982c19:dd:d9:dd:c25:c25:1:70c2/1272c19:dd:d9:dd:c25:c25:1:70c3
992c19:dd:d9:dd:c25:c25:1:70c4/1272c19:dd:d9:dd:c25:c25:1:70c5
1002c19:dd:d9:dd:c25:c25:1:70c6/1272c19:dd:d9:dd:c25:c25:1:70c7
1012c19:dd:d9:dd:c25:c25:1:70c8/1272c19:dd:d9:dd:c25:c25:1:70c9
1022c19:dd:d9:dd:c25:c25:1:70ca/1272c19:dd:d9:dd:c25:c25:1:70cb
1032c19:dd:d9:dd:c25:c25:1:70cc/1272c19:dd:d9:dd:c25:c25:1:70cd
1042c19:dd:d9:dd:c25:c25:1:70ce/1272c19:dd:d9:dd:c25:c25:1:70cf
1052c19:dd:d9:dd:c25:c25:1:70d0/1272c19:dd:d9:dd:c25:c25:1:70d1
1062c19:dd:d9:dd:c25:c25:1:70d2/1272c19:dd:d9:dd:c25:c25:1:70d3
1072c19:dd:d9:dd:c25:c25:1:70d4/1272c19:dd:d9:dd:c25:c25:1:70d5
1082c19:dd:d9:dd:c25:c25:1:70d6/1272c19:dd:d9:dd:c25:c25:1:70d7
1092c19:dd:d9:dd:c25:c25:1:70d8/1272c19:dd:d9:dd:c25:c25:1:70d9
1102c19:dd:d9:dd:c25:c25:1:70da/1272c19:dd:d9:dd:c25:c25:1:70db
1112c19:dd:d9:dd:c25:c25:1:70dc/1272c19:dd:d9:dd:c25:c25:1:70dd
1122c19:dd:d9:dd:c25:c25:1:70de/1272c19:dd:d9:dd:c25:c25:1:70df
1132c19:dd:d9:dd:c25:c25:1:70e0/1272c19:dd:d9:dd:c25:c25:1:70e1
1142c19:dd:d9:dd:c25:c25:1:70e2/1272c19:dd:d9:dd:c25:c25:1:70e3
1152c19:dd:d9:dd:c25:c25:1:70e4/1272c19:dd:d9:dd:c25:c25:1:70e5
1162c19:dd:d9:dd:c25:c25:1:70e6/1272c19:dd:d9:dd:c25:c25:1:70e7
1172c19:dd:d9:dd:c25:c25:1:70e8/1272c19:dd:d9:dd:c25:c25:1:70e9
1182c19:dd:d9:dd:c25:c25:1:70ea/1272c19:dd:d9:dd:c25:c25:1:70eb
1192c19:dd:d9:dd:c25:c25:1:70ec/1272c19:dd:d9:dd:c25:c25:1:70ed
1202c19:dd:d9:dd:c25:c25:1:70ee/1272c19:dd:d9:dd:c25:c25:1:70ef
1212c19:dd:d9:dd:c25:c25:1:70f0/1272c19:dd:d9:dd:c25:c25:1:70f1
1222c19:dd:d9:dd:c25:c25:1:70f2/1272c19:dd:d9:dd:c25:c25:1:70f3
1232c19:dd:d9:dd:c25:c25:1:70f4/1272c19:dd:d9:dd:c25:c25:1:70f5
1242c19:dd:d9:dd:c25:c25:1:70f6/1272c19:dd:d9:dd:c25:c25:1:70f7
1252c19:dd:d9:dd:c25:c25:1:70f8/1272c19:dd:d9:dd:c25:c25:1:70f9
1262c19:dd:d9:dd:c25:c25:1:70fa/1272c19:dd:d9:dd:c25:c25:1:70fb
1272c19:dd:d9:dd:c25:c25:1:70fc/1272c19:dd:d9:dd:c25:c25:1:70fd
1282c19:dd:d9:dd:c25:c25:1:70fe/1272c19:dd:d9:dd:c25:c25:1:70ff
1292c19:dd:d9:dd:c25:c25:1:7100/1272c19:dd:d9:dd:c25:c25:1:7101
1302c19:dd:d9:dd:c25:c25:1:7102/1272c19:dd:d9:dd:c25:c25:1:7103
1312c19:dd:d9:dd:c25:c25:1:7104/1272c19:dd:d9:dd:c25:c25:1:7105
1322c19:dd:d9:dd:c25:c25:1:7106/1272c19:dd:d9:dd:c25:c25:1:7107
1332c19:dd:d9:dd:c25:c25:1:7108/1272c19:dd:d9:dd:c25:c25:1:7109
1342c19:dd:d9:dd:c25:c25:1:710a/1272c19:dd:d9:dd:c25:c25:1:710b
1352c19:dd:d9:dd:c25:c25:1:710c/1272c19:dd:d9:dd:c25:c25:1:710d
1362c19:dd:d9:dd:c25:c25:1:710e/1272c19:dd:d9:dd:c25:c25:1:710f
1372c19:dd:d9:dd:c25:c25:1:7110/1272c19:dd:d9:dd:c25:c25:1:7111
1382c19:dd:d9:dd:c25:c25:1:7112/1272c19:dd:d9:dd:c25:c25:1:7113
1392c19:dd:d9:dd:c25:c25:1:7114/1272c19:dd:d9:dd:c25:c25:1:7115
1402c19:dd:d9:dd:c25:c25:1:7116/1272c19:dd:d9:dd:c25:c25:1:7117
1412c19:dd:d9:dd:c25:c25:1:7118/1272c19:dd:d9:dd:c25:c25:1:7119
1422c19:dd:d9:dd:c25:c25:1:711a/1272c19:dd:d9:dd:c25:c25:1:711b
1432c19:dd:d9:dd:c25:c25:1:711c/1272c19:dd:d9:dd:c25:c25:1:711d
1442c19:dd:d9:dd:c25:c25:1:711e/1272c19:dd:d9:dd:c25:c25:1:711f
1452c19:dd:d9:dd:c25:c25:1:7120/1272c19:dd:d9:dd:c25:c25:1:7121
1462c19:dd:d9:dd:c25:c25:1:7122/1272c19:dd:d9:dd:c25:c25:1:7123
1472c19:dd:d9:dd:c25:c25:1:7124/1272c19:dd:d9:dd:c25:c25:1:7125
1482c19:dd:d9:dd:c25:c25:1:7126/1272c19:dd:d9:dd:c25:c25:1:7127
1492c19:dd:d9:dd:c25:c25:1:7128/1272c19:dd:d9:dd:c25:c25:1:7129
1502c19:dd:d9:dd:c25:c25:1:712a/1272c19:dd:d9:dd:c25:c25:1:712b
1512c19:dd:d9:dd:c25:c25:1:712c/1272c19:dd:d9:dd:c25:c25:1:712d
1522c19:dd:d9:dd:c25:c25:1:712e/1272c19:dd:d9:dd:c25:c25:1:712f
1532c19:dd:d9:dd:c25:c25:1:7130/1272c19:dd:d9:dd:c25:c25:1:7131
1542c19:dd:d9:dd:c25:c25:1:7132/1272c19:dd:d9:dd:c25:c25:1:7133
1552c19:dd:d9:dd:c25:c25:1:7134/1272c19:dd:d9:dd:c25:c25:1:7135
1562c19:dd:d9:dd:c25:c25:1:7136/1272c19:dd:d9:dd:c25:c25:1:7137
1572c19:dd:d9:dd:c25:c25:1:7138/1272c19:dd:d9:dd:c25:c25:1:7139
1582c19:dd:d9:dd:c25:c25:1:713a/1272c19:dd:d9:dd:c25:c25:1:713b
1592c19:dd:d9:dd:c25:c25:1:713c/1272c19:dd:d9:dd:c25:c25:1:713d
1602c19:dd:d9:dd:c25:c25:1:713e/1272c19:dd:d9:dd:c25:c25:1:713f
1612c19:dd:d9:dd:c25:c25:1:7140/1272c19:dd:d9:dd:c25:c25:1:7141
1622c19:dd:d9:dd:c25:c25:1:7142/1272c19:dd:d9:dd:c25:c25:1:7143
1632c19:dd:d9:dd:c25:c25:1:7144/1272c19:dd:d9:dd:c25:c25:1:7145
1642c19:dd:d9:dd:c25:c25:1:7146/1272c19:dd:d9:dd:c25:c25:1:7147
1652c19:dd:d9:dd:c25:c25:1:7148/1272c19:dd:d9:dd:c25:c25:1:7149
1662c19:dd:d9:dd:c25:c25:1:714a/1272c19:dd:d9:dd:c25:c25:1:714b
1672c19:dd:d9:dd:c25:c25:1:714c/1272c19:dd:d9:dd:c25:c25:1:714d
1682c19:dd:d9:dd:c25:c25:1:714e/1272c19:dd:d9:dd:c25:c25:1:714f
1692c19:dd:d9:dd:c25:c25:1:7150/1272c19:dd:d9:dd:c25:c25:1:7151
1702c19:dd:d9:dd:c25:c25:1:7152/1272c19:dd:d9:dd:c25:c25:1:7153
1712c19:dd:d9:dd:c25:c25:1:7154/1272c19:dd:d9:dd:c25:c25:1:7155
1722c19:dd:d9:dd:c25:c25:1:7156/1272c19:dd:d9:dd:c25:c25:1:7157
1732c19:dd:d9:dd:c25:c25:1:7158/1272c19:dd:d9:dd:c25:c25:1:7159
1742c19:dd:d9:dd:c25:c25:1:715a/1272c19:dd:d9:dd:c25:c25:1:715b
1752c19:dd:d9:dd:c25:c25:1:715c/1272c19:dd:d9:dd:c25:c25:1:715d
1762c19:dd:d9:dd:c25:c25:1:715e/1272c19:dd:d9:dd:c25:c25:1:715f
1772c19:dd:d9:dd:c25:c25:1:7160/1272c19:dd:d9:dd:c25:c25:1:7161
1782c19:dd:d9:dd:c25:c25:1:7162/1272c19:dd:d9:dd:c25:c25:1:7163
1792c19:dd:d9:dd:c25:c25:1:7164/1272c19:dd:d9:dd:c25:c25:1:7165
1802c19:dd:d9:dd:c25:c25:1:7166/1272c19:dd:d9:dd:c25:c25:1:7167
1812c19:dd:d9:dd:c25:c25:1:7168/1272c19:dd:d9:dd:c25:c25:1:7169
1822c19:dd:d9:dd:c25:c25:1:716a/1272c19:dd:d9:dd:c25:c25:1:716b
1832c19:dd:d9:dd:c25:c25:1:716c/1272c19:dd:d9:dd:c25:c25:1:716d
1842c19:dd:d9:dd:c25:c25:1:716e/1272c19:dd:d9:dd:c25:c25:1:716f
1852c19:dd:d9:dd:c25:c25:1:7170/1272c19:dd:d9:dd:c25:c25:1:7171
1862c19:dd:d9:dd:c25:c25:1:7172/1272c19:dd:d9:dd:c25:c25:1:7173
1872c19:dd:d9:dd:c25:c25:1:7174/1272c19:dd:d9:dd:c25:c25:1:7175
1882c19:dd:d9:dd:c25:c25:1:7176/1272c19:dd:d9:dd:c25:c25:1:7177
1892c19:dd:d9:dd:c25:c25:1:7178/1272c19:dd:d9:dd:c25:c25:1:7179
1902c19:dd:d9:dd:c25:c25:1:717a/1272c19:dd:d9:dd:c25:c25:1:717b
1912c19:dd:d9:dd:c25:c25:1:717c/1272c19:dd:d9:dd:c25:c25:1:717d
1922c19:dd:d9:dd:c25:c25:1:717e/1272c19:dd:d9:dd:c25:c25:1:717f
1932c19:dd:d9:dd:c25:c25:1:7180/1272c19:dd:d9:dd:c25:c25:1:7181
1942c19:dd:d9:dd:c25:c25:1:7182/1272c19:dd:d9:dd:c25:c25:1:7183
1952c19:dd:d9:dd:c25:c25:1:7184/1272c19:dd:d9:dd:c25:c25:1:7185
1962c19:dd:d9:dd:c25:c25:1:7186/1272c19:dd:d9:dd:c25:c25:1:7187
1972c19:dd:d9:dd:c25:c25:1:7188/1272c19:dd:d9:dd:c25:c25:1:7189
1982c19:dd:d9:dd:c25:c25:1:718a/1272c19:dd:d9:dd:c25:c25:1:718b
1992c19:dd:d9:dd:c25:c25:1:718c/1272c19:dd:d9:dd:c25:c25:1:718d
2002c19:dd:d9:dd:c25:c25:1:718e/1272c19:dd:d9:dd:c25:c25:1:718f
2012c19:dd:d9:dd:c25:c25:1:7190/1272c19:dd:d9:dd:c25:c25:1:7191
2022c19:dd:d9:dd:c25:c25:1:7192/1272c19:dd:d9:dd:c25:c25:1:7193
2032c19:dd:d9:dd:c25:c25:1:7194/1272c19:dd:d9:dd:c25:c25:1:7195
2042c19:dd:d9:dd:c25:c25:1:7196/1272c19:dd:d9:dd:c25:c25:1:7197
2052c19:dd:d9:dd:c25:c25:1:7198/1272c19:dd:d9:dd:c25:c25:1:7199
2062c19:dd:d9:dd:c25:c25:1:719a/1272c19:dd:d9:dd:c25:c25:1:719b
2072c19:dd:d9:dd:c25:c25:1:719c/1272c19:dd:d9:dd:c25:c25:1:719d
2082c19:dd:d9:dd:c25:c25:1:719e/1272c19:dd:d9:dd:c25:c25:1:719f
2092c19:dd:d9:dd:c25:c25:1:71a0/1272c19:dd:d9:dd:c25:c25:1:71a1
2102c19:dd:d9:dd:c25:c25:1:71a2/1272c19:dd:d9:dd:c25:c25:1:71a3
2112c19:dd:d9:dd:c25:c25:1:71a4/1272c19:dd:d9:dd:c25:c25:1:71a5
2122c19:dd:d9:dd:c25:c25:1:71a6/1272c19:dd:d9:dd:c25:c25:1:71a7
2132c19:dd:d9:dd:c25:c25:1:71a8/1272c19:dd:d9:dd:c25:c25:1:71a9
2142c19:dd:d9:dd:c25:c25:1:71aa/1272c19:dd:d9:dd:c25:c25:1:71ab
2152c19:dd:d9:dd:c25:c25:1:71ac/1272c19:dd:d9:dd:c25:c25:1:71ad
2162c19:dd:d9:dd:c25:c25:1:71ae/1272c19:dd:d9:dd:c25:c25:1:71af
2172c19:dd:d9:dd:c25:c25:1:71b0/1272c19:dd:d9:dd:c25:c25:1:71b1
2182c19:dd:d9:dd:c25:c25:1:71b2/1272c19:dd:d9:dd:c25:c25:1:71b3
2192c19:dd:d9:dd:c25:c25:1:71b4/1272c19:dd:d9:dd:c25:c25:1:71b5
2202c19:dd:d9:dd:c25:c25:1:71b6/1272c19:dd:d9:dd:c25:c25:1:71b7
2212c19:dd:d9:dd:c25:c25:1:71b8/1272c19:dd:d9:dd:c25:c25:1:71b9
2222c19:dd:d9:dd:c25:c25:1:71ba/1272c19:dd:d9:dd:c25:c25:1:71bb
2232c19:dd:d9:dd:c25:c25:1:71bc/1272c19:dd:d9:dd:c25:c25:1:71bd
2242c19:dd:d9:dd:c25:c25:1:71be/1272c19:dd:d9:dd:c25:c25:1:71bf
2252c19:dd:d9:dd:c25:c25:1:71c0/1272c19:dd:d9:dd:c25:c25:1:71c1
2262c19:dd:d9:dd:c25:c25:1:71c2/1272c19:dd:d9:dd:c25:c25:1:71c3
2272c19:dd:d9:dd:c25:c25:1:71c4/1272c19:dd:d9:dd:c25:c25:1:71c5
2282c19:dd:d9:dd:c25:c25:1:71c6/1272c19:dd:d9:dd:c25:c25:1:71c7
2292c19:dd:d9:dd:c25:c25:1:71c8/1272c19:dd:d9:dd:c25:c25:1:71c9
2302c19:dd:d9:dd:c25:c25:1:71ca/1272c19:dd:d9:dd:c25:c25:1:71cb
2312c19:dd:d9:dd:c25:c25:1:71cc/1272c19:dd:d9:dd:c25:c25:1:71cd
2322c19:dd:d9:dd:c25:c25:1:71ce/1272c19:dd:d9:dd:c25:c25:1:71cf
2332c19:dd:d9:dd:c25:c25:1:71d0/1272c19:dd:d9:dd:c25:c25:1:71d1
2342c19:dd:d9:dd:c25:c25:1:71d2/1272c19:dd:d9:dd:c25:c25:1:71d3
2352c19:dd:d9:dd:c25:c25:1:71d4/1272c19:dd:d9:dd:c25:c25:1:71d5
2362c19:dd:d9:dd:c25:c25:1:71d6/1272c19:dd:d9:dd:c25:c25:1:71d7
2372c19:dd:d9:dd:c25:c25:1:71d8/1272c19:dd:d9:dd:c25:c25:1:71d9
2382c19:dd:d9:dd:c25:c25:1:71da/1272c19:dd:d9:dd:c25:c25:1:71db
2392c19:dd:d9:dd:c25:c25:1:71dc/1272c19:dd:d9:dd:c25:c25:1:71dd
2402c19:dd:d9:dd:c25:c25:1:71de/1272c19:dd:d9:dd:c25:c25:1:71df
2412c19:dd:d9:dd:c25:c25:1:71e0/1272c19:dd:d9:dd:c25:c25:1:71e1
2422c19:dd:d9:dd:c25:c25:1:71e2/1272c19:dd:d9:dd:c25:c25:1:71e3
2432c19:dd:d9:dd:c25:c25:1:71e4/1272c19:dd:d9:dd:c25:c25:1:71e5
2442c19:dd:d9:dd:c25:c25:1:71e6/1272c19:dd:d9:dd:c25:c25:1:71e7
2452c19:dd:d9:dd:c25:c25:1:71e8/1272c19:dd:d9:dd:c25:c25:1:71e9
2462c19:dd:d9:dd:c25:c25:1:71ea/1272c19:dd:d9:dd:c25:c25:1:71eb
2472c19:dd:d9:dd:c25:c25:1:71ec/1272c19:dd:d9:dd:c25:c25:1:71ed
2482c19:dd:d9:dd:c25:c25:1:71ee/1272c19:dd:d9:dd:c25:c25:1:71ef
2492c19:dd:d9:dd:c25:c25:1:71f0/1272c19:dd:d9:dd:c25:c25:1:71f1
2502c19:dd:d9:dd:c25:c25:1:71f2/1272c19:dd:d9:dd:c25:c25:1:71f3
2512c19:dd:d9:dd:c25:c25:1:71f4/1272c19:dd:d9:dd:c25:c25:1:71f5
2522c19:dd:d9:dd:c25:c25:1:71f6/1272c19:dd:d9:dd:c25:c25:1:71f7
2532c19:dd:d9:dd:c25:c25:1:71f8/1272c19:dd:d9:dd:c25:c25:1:71f9
2542c19:dd:d9:dd:c25:c25:1:71fa/1272c19:dd:d9:dd:c25:c25:1:71fb
2552c19:dd:d9:dd:c25:c25:1:71fc/1272c19:dd:d9:dd:c25:c25:1:71fd
2562c19:dd:d9:dd:c25:c25:1:71fe/1272c19:dd:d9:dd:c25:c25:1:71ff

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.