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:f004:1000/116
First address
2c19:dd:d9:dd:c25:c25:f004:1000
Last address
2c19:dd:d9:dd:c25:c25:f004:1fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:f004:1000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
1.4.0.0.f.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:f004:1000/116 makes 2,048 subnets of /127; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:f004:1000/1272c19:dd:d9:dd:c25:c25:f004:1001
22c19:dd:d9:dd:c25:c25:f004:1002/1272c19:dd:d9:dd:c25:c25:f004:1003
32c19:dd:d9:dd:c25:c25:f004:1004/1272c19:dd:d9:dd:c25:c25:f004:1005
42c19:dd:d9:dd:c25:c25:f004:1006/1272c19:dd:d9:dd:c25:c25:f004:1007
52c19:dd:d9:dd:c25:c25:f004:1008/1272c19:dd:d9:dd:c25:c25:f004:1009
62c19:dd:d9:dd:c25:c25:f004:100a/1272c19:dd:d9:dd:c25:c25:f004:100b
72c19:dd:d9:dd:c25:c25:f004:100c/1272c19:dd:d9:dd:c25:c25:f004:100d
82c19:dd:d9:dd:c25:c25:f004:100e/1272c19:dd:d9:dd:c25:c25:f004:100f
92c19:dd:d9:dd:c25:c25:f004:1010/1272c19:dd:d9:dd:c25:c25:f004:1011
102c19:dd:d9:dd:c25:c25:f004:1012/1272c19:dd:d9:dd:c25:c25:f004:1013
112c19:dd:d9:dd:c25:c25:f004:1014/1272c19:dd:d9:dd:c25:c25:f004:1015
122c19:dd:d9:dd:c25:c25:f004:1016/1272c19:dd:d9:dd:c25:c25:f004:1017
132c19:dd:d9:dd:c25:c25:f004:1018/1272c19:dd:d9:dd:c25:c25:f004:1019
142c19:dd:d9:dd:c25:c25:f004:101a/1272c19:dd:d9:dd:c25:c25:f004:101b
152c19:dd:d9:dd:c25:c25:f004:101c/1272c19:dd:d9:dd:c25:c25:f004:101d
162c19:dd:d9:dd:c25:c25:f004:101e/1272c19:dd:d9:dd:c25:c25:f004:101f
172c19:dd:d9:dd:c25:c25:f004:1020/1272c19:dd:d9:dd:c25:c25:f004:1021
182c19:dd:d9:dd:c25:c25:f004:1022/1272c19:dd:d9:dd:c25:c25:f004:1023
192c19:dd:d9:dd:c25:c25:f004:1024/1272c19:dd:d9:dd:c25:c25:f004:1025
202c19:dd:d9:dd:c25:c25:f004:1026/1272c19:dd:d9:dd:c25:c25:f004:1027
212c19:dd:d9:dd:c25:c25:f004:1028/1272c19:dd:d9:dd:c25:c25:f004:1029
222c19:dd:d9:dd:c25:c25:f004:102a/1272c19:dd:d9:dd:c25:c25:f004:102b
232c19:dd:d9:dd:c25:c25:f004:102c/1272c19:dd:d9:dd:c25:c25:f004:102d
242c19:dd:d9:dd:c25:c25:f004:102e/1272c19:dd:d9:dd:c25:c25:f004:102f
252c19:dd:d9:dd:c25:c25:f004:1030/1272c19:dd:d9:dd:c25:c25:f004:1031
262c19:dd:d9:dd:c25:c25:f004:1032/1272c19:dd:d9:dd:c25:c25:f004:1033
272c19:dd:d9:dd:c25:c25:f004:1034/1272c19:dd:d9:dd:c25:c25:f004:1035
282c19:dd:d9:dd:c25:c25:f004:1036/1272c19:dd:d9:dd:c25:c25:f004:1037
292c19:dd:d9:dd:c25:c25:f004:1038/1272c19:dd:d9:dd:c25:c25:f004:1039
302c19:dd:d9:dd:c25:c25:f004:103a/1272c19:dd:d9:dd:c25:c25:f004:103b
312c19:dd:d9:dd:c25:c25:f004:103c/1272c19:dd:d9:dd:c25:c25:f004:103d
322c19:dd:d9:dd:c25:c25:f004:103e/1272c19:dd:d9:dd:c25:c25:f004:103f
332c19:dd:d9:dd:c25:c25:f004:1040/1272c19:dd:d9:dd:c25:c25:f004:1041
342c19:dd:d9:dd:c25:c25:f004:1042/1272c19:dd:d9:dd:c25:c25:f004:1043
352c19:dd:d9:dd:c25:c25:f004:1044/1272c19:dd:d9:dd:c25:c25:f004:1045
362c19:dd:d9:dd:c25:c25:f004:1046/1272c19:dd:d9:dd:c25:c25:f004:1047
372c19:dd:d9:dd:c25:c25:f004:1048/1272c19:dd:d9:dd:c25:c25:f004:1049
382c19:dd:d9:dd:c25:c25:f004:104a/1272c19:dd:d9:dd:c25:c25:f004:104b
392c19:dd:d9:dd:c25:c25:f004:104c/1272c19:dd:d9:dd:c25:c25:f004:104d
402c19:dd:d9:dd:c25:c25:f004:104e/1272c19:dd:d9:dd:c25:c25:f004:104f
412c19:dd:d9:dd:c25:c25:f004:1050/1272c19:dd:d9:dd:c25:c25:f004:1051
422c19:dd:d9:dd:c25:c25:f004:1052/1272c19:dd:d9:dd:c25:c25:f004:1053
432c19:dd:d9:dd:c25:c25:f004:1054/1272c19:dd:d9:dd:c25:c25:f004:1055
442c19:dd:d9:dd:c25:c25:f004:1056/1272c19:dd:d9:dd:c25:c25:f004:1057
452c19:dd:d9:dd:c25:c25:f004:1058/1272c19:dd:d9:dd:c25:c25:f004:1059
462c19:dd:d9:dd:c25:c25:f004:105a/1272c19:dd:d9:dd:c25:c25:f004:105b
472c19:dd:d9:dd:c25:c25:f004:105c/1272c19:dd:d9:dd:c25:c25:f004:105d
482c19:dd:d9:dd:c25:c25:f004:105e/1272c19:dd:d9:dd:c25:c25:f004:105f
492c19:dd:d9:dd:c25:c25:f004:1060/1272c19:dd:d9:dd:c25:c25:f004:1061
502c19:dd:d9:dd:c25:c25:f004:1062/1272c19:dd:d9:dd:c25:c25:f004:1063
512c19:dd:d9:dd:c25:c25:f004:1064/1272c19:dd:d9:dd:c25:c25:f004:1065
522c19:dd:d9:dd:c25:c25:f004:1066/1272c19:dd:d9:dd:c25:c25:f004:1067
532c19:dd:d9:dd:c25:c25:f004:1068/1272c19:dd:d9:dd:c25:c25:f004:1069
542c19:dd:d9:dd:c25:c25:f004:106a/1272c19:dd:d9:dd:c25:c25:f004:106b
552c19:dd:d9:dd:c25:c25:f004:106c/1272c19:dd:d9:dd:c25:c25:f004:106d
562c19:dd:d9:dd:c25:c25:f004:106e/1272c19:dd:d9:dd:c25:c25:f004:106f
572c19:dd:d9:dd:c25:c25:f004:1070/1272c19:dd:d9:dd:c25:c25:f004:1071
582c19:dd:d9:dd:c25:c25:f004:1072/1272c19:dd:d9:dd:c25:c25:f004:1073
592c19:dd:d9:dd:c25:c25:f004:1074/1272c19:dd:d9:dd:c25:c25:f004:1075
602c19:dd:d9:dd:c25:c25:f004:1076/1272c19:dd:d9:dd:c25:c25:f004:1077
612c19:dd:d9:dd:c25:c25:f004:1078/1272c19:dd:d9:dd:c25:c25:f004:1079
622c19:dd:d9:dd:c25:c25:f004:107a/1272c19:dd:d9:dd:c25:c25:f004:107b
632c19:dd:d9:dd:c25:c25:f004:107c/1272c19:dd:d9:dd:c25:c25:f004:107d
642c19:dd:d9:dd:c25:c25:f004:107e/1272c19:dd:d9:dd:c25:c25:f004:107f
652c19:dd:d9:dd:c25:c25:f004:1080/1272c19:dd:d9:dd:c25:c25:f004:1081
662c19:dd:d9:dd:c25:c25:f004:1082/1272c19:dd:d9:dd:c25:c25:f004:1083
672c19:dd:d9:dd:c25:c25:f004:1084/1272c19:dd:d9:dd:c25:c25:f004:1085
682c19:dd:d9:dd:c25:c25:f004:1086/1272c19:dd:d9:dd:c25:c25:f004:1087
692c19:dd:d9:dd:c25:c25:f004:1088/1272c19:dd:d9:dd:c25:c25:f004:1089
702c19:dd:d9:dd:c25:c25:f004:108a/1272c19:dd:d9:dd:c25:c25:f004:108b
712c19:dd:d9:dd:c25:c25:f004:108c/1272c19:dd:d9:dd:c25:c25:f004:108d
722c19:dd:d9:dd:c25:c25:f004:108e/1272c19:dd:d9:dd:c25:c25:f004:108f
732c19:dd:d9:dd:c25:c25:f004:1090/1272c19:dd:d9:dd:c25:c25:f004:1091
742c19:dd:d9:dd:c25:c25:f004:1092/1272c19:dd:d9:dd:c25:c25:f004:1093
752c19:dd:d9:dd:c25:c25:f004:1094/1272c19:dd:d9:dd:c25:c25:f004:1095
762c19:dd:d9:dd:c25:c25:f004:1096/1272c19:dd:d9:dd:c25:c25:f004:1097
772c19:dd:d9:dd:c25:c25:f004:1098/1272c19:dd:d9:dd:c25:c25:f004:1099
782c19:dd:d9:dd:c25:c25:f004:109a/1272c19:dd:d9:dd:c25:c25:f004:109b
792c19:dd:d9:dd:c25:c25:f004:109c/1272c19:dd:d9:dd:c25:c25:f004:109d
802c19:dd:d9:dd:c25:c25:f004:109e/1272c19:dd:d9:dd:c25:c25:f004:109f
812c19:dd:d9:dd:c25:c25:f004:10a0/1272c19:dd:d9:dd:c25:c25:f004:10a1
822c19:dd:d9:dd:c25:c25:f004:10a2/1272c19:dd:d9:dd:c25:c25:f004:10a3
832c19:dd:d9:dd:c25:c25:f004:10a4/1272c19:dd:d9:dd:c25:c25:f004:10a5
842c19:dd:d9:dd:c25:c25:f004:10a6/1272c19:dd:d9:dd:c25:c25:f004:10a7
852c19:dd:d9:dd:c25:c25:f004:10a8/1272c19:dd:d9:dd:c25:c25:f004:10a9
862c19:dd:d9:dd:c25:c25:f004:10aa/1272c19:dd:d9:dd:c25:c25:f004:10ab
872c19:dd:d9:dd:c25:c25:f004:10ac/1272c19:dd:d9:dd:c25:c25:f004:10ad
882c19:dd:d9:dd:c25:c25:f004:10ae/1272c19:dd:d9:dd:c25:c25:f004:10af
892c19:dd:d9:dd:c25:c25:f004:10b0/1272c19:dd:d9:dd:c25:c25:f004:10b1
902c19:dd:d9:dd:c25:c25:f004:10b2/1272c19:dd:d9:dd:c25:c25:f004:10b3
912c19:dd:d9:dd:c25:c25:f004:10b4/1272c19:dd:d9:dd:c25:c25:f004:10b5
922c19:dd:d9:dd:c25:c25:f004:10b6/1272c19:dd:d9:dd:c25:c25:f004:10b7
932c19:dd:d9:dd:c25:c25:f004:10b8/1272c19:dd:d9:dd:c25:c25:f004:10b9
942c19:dd:d9:dd:c25:c25:f004:10ba/1272c19:dd:d9:dd:c25:c25:f004:10bb
952c19:dd:d9:dd:c25:c25:f004:10bc/1272c19:dd:d9:dd:c25:c25:f004:10bd
962c19:dd:d9:dd:c25:c25:f004:10be/1272c19:dd:d9:dd:c25:c25:f004:10bf
972c19:dd:d9:dd:c25:c25:f004:10c0/1272c19:dd:d9:dd:c25:c25:f004:10c1
982c19:dd:d9:dd:c25:c25:f004:10c2/1272c19:dd:d9:dd:c25:c25:f004:10c3
992c19:dd:d9:dd:c25:c25:f004:10c4/1272c19:dd:d9:dd:c25:c25:f004:10c5
1002c19:dd:d9:dd:c25:c25:f004:10c6/1272c19:dd:d9:dd:c25:c25:f004:10c7
1012c19:dd:d9:dd:c25:c25:f004:10c8/1272c19:dd:d9:dd:c25:c25:f004:10c9
1022c19:dd:d9:dd:c25:c25:f004:10ca/1272c19:dd:d9:dd:c25:c25:f004:10cb
1032c19:dd:d9:dd:c25:c25:f004:10cc/1272c19:dd:d9:dd:c25:c25:f004:10cd
1042c19:dd:d9:dd:c25:c25:f004:10ce/1272c19:dd:d9:dd:c25:c25:f004:10cf
1052c19:dd:d9:dd:c25:c25:f004:10d0/1272c19:dd:d9:dd:c25:c25:f004:10d1
1062c19:dd:d9:dd:c25:c25:f004:10d2/1272c19:dd:d9:dd:c25:c25:f004:10d3
1072c19:dd:d9:dd:c25:c25:f004:10d4/1272c19:dd:d9:dd:c25:c25:f004:10d5
1082c19:dd:d9:dd:c25:c25:f004:10d6/1272c19:dd:d9:dd:c25:c25:f004:10d7
1092c19:dd:d9:dd:c25:c25:f004:10d8/1272c19:dd:d9:dd:c25:c25:f004:10d9
1102c19:dd:d9:dd:c25:c25:f004:10da/1272c19:dd:d9:dd:c25:c25:f004:10db
1112c19:dd:d9:dd:c25:c25:f004:10dc/1272c19:dd:d9:dd:c25:c25:f004:10dd
1122c19:dd:d9:dd:c25:c25:f004:10de/1272c19:dd:d9:dd:c25:c25:f004:10df
1132c19:dd:d9:dd:c25:c25:f004:10e0/1272c19:dd:d9:dd:c25:c25:f004:10e1
1142c19:dd:d9:dd:c25:c25:f004:10e2/1272c19:dd:d9:dd:c25:c25:f004:10e3
1152c19:dd:d9:dd:c25:c25:f004:10e4/1272c19:dd:d9:dd:c25:c25:f004:10e5
1162c19:dd:d9:dd:c25:c25:f004:10e6/1272c19:dd:d9:dd:c25:c25:f004:10e7
1172c19:dd:d9:dd:c25:c25:f004:10e8/1272c19:dd:d9:dd:c25:c25:f004:10e9
1182c19:dd:d9:dd:c25:c25:f004:10ea/1272c19:dd:d9:dd:c25:c25:f004:10eb
1192c19:dd:d9:dd:c25:c25:f004:10ec/1272c19:dd:d9:dd:c25:c25:f004:10ed
1202c19:dd:d9:dd:c25:c25:f004:10ee/1272c19:dd:d9:dd:c25:c25:f004:10ef
1212c19:dd:d9:dd:c25:c25:f004:10f0/1272c19:dd:d9:dd:c25:c25:f004:10f1
1222c19:dd:d9:dd:c25:c25:f004:10f2/1272c19:dd:d9:dd:c25:c25:f004:10f3
1232c19:dd:d9:dd:c25:c25:f004:10f4/1272c19:dd:d9:dd:c25:c25:f004:10f5
1242c19:dd:d9:dd:c25:c25:f004:10f6/1272c19:dd:d9:dd:c25:c25:f004:10f7
1252c19:dd:d9:dd:c25:c25:f004:10f8/1272c19:dd:d9:dd:c25:c25:f004:10f9
1262c19:dd:d9:dd:c25:c25:f004:10fa/1272c19:dd:d9:dd:c25:c25:f004:10fb
1272c19:dd:d9:dd:c25:c25:f004:10fc/1272c19:dd:d9:dd:c25:c25:f004:10fd
1282c19:dd:d9:dd:c25:c25:f004:10fe/1272c19:dd:d9:dd:c25:c25:f004:10ff
1292c19:dd:d9:dd:c25:c25:f004:1100/1272c19:dd:d9:dd:c25:c25:f004:1101
1302c19:dd:d9:dd:c25:c25:f004:1102/1272c19:dd:d9:dd:c25:c25:f004:1103
1312c19:dd:d9:dd:c25:c25:f004:1104/1272c19:dd:d9:dd:c25:c25:f004:1105
1322c19:dd:d9:dd:c25:c25:f004:1106/1272c19:dd:d9:dd:c25:c25:f004:1107
1332c19:dd:d9:dd:c25:c25:f004:1108/1272c19:dd:d9:dd:c25:c25:f004:1109
1342c19:dd:d9:dd:c25:c25:f004:110a/1272c19:dd:d9:dd:c25:c25:f004:110b
1352c19:dd:d9:dd:c25:c25:f004:110c/1272c19:dd:d9:dd:c25:c25:f004:110d
1362c19:dd:d9:dd:c25:c25:f004:110e/1272c19:dd:d9:dd:c25:c25:f004:110f
1372c19:dd:d9:dd:c25:c25:f004:1110/1272c19:dd:d9:dd:c25:c25:f004:1111
1382c19:dd:d9:dd:c25:c25:f004:1112/1272c19:dd:d9:dd:c25:c25:f004:1113
1392c19:dd:d9:dd:c25:c25:f004:1114/1272c19:dd:d9:dd:c25:c25:f004:1115
1402c19:dd:d9:dd:c25:c25:f004:1116/1272c19:dd:d9:dd:c25:c25:f004:1117
1412c19:dd:d9:dd:c25:c25:f004:1118/1272c19:dd:d9:dd:c25:c25:f004:1119
1422c19:dd:d9:dd:c25:c25:f004:111a/1272c19:dd:d9:dd:c25:c25:f004:111b
1432c19:dd:d9:dd:c25:c25:f004:111c/1272c19:dd:d9:dd:c25:c25:f004:111d
1442c19:dd:d9:dd:c25:c25:f004:111e/1272c19:dd:d9:dd:c25:c25:f004:111f
1452c19:dd:d9:dd:c25:c25:f004:1120/1272c19:dd:d9:dd:c25:c25:f004:1121
1462c19:dd:d9:dd:c25:c25:f004:1122/1272c19:dd:d9:dd:c25:c25:f004:1123
1472c19:dd:d9:dd:c25:c25:f004:1124/1272c19:dd:d9:dd:c25:c25:f004:1125
1482c19:dd:d9:dd:c25:c25:f004:1126/1272c19:dd:d9:dd:c25:c25:f004:1127
1492c19:dd:d9:dd:c25:c25:f004:1128/1272c19:dd:d9:dd:c25:c25:f004:1129
1502c19:dd:d9:dd:c25:c25:f004:112a/1272c19:dd:d9:dd:c25:c25:f004:112b
1512c19:dd:d9:dd:c25:c25:f004:112c/1272c19:dd:d9:dd:c25:c25:f004:112d
1522c19:dd:d9:dd:c25:c25:f004:112e/1272c19:dd:d9:dd:c25:c25:f004:112f
1532c19:dd:d9:dd:c25:c25:f004:1130/1272c19:dd:d9:dd:c25:c25:f004:1131
1542c19:dd:d9:dd:c25:c25:f004:1132/1272c19:dd:d9:dd:c25:c25:f004:1133
1552c19:dd:d9:dd:c25:c25:f004:1134/1272c19:dd:d9:dd:c25:c25:f004:1135
1562c19:dd:d9:dd:c25:c25:f004:1136/1272c19:dd:d9:dd:c25:c25:f004:1137
1572c19:dd:d9:dd:c25:c25:f004:1138/1272c19:dd:d9:dd:c25:c25:f004:1139
1582c19:dd:d9:dd:c25:c25:f004:113a/1272c19:dd:d9:dd:c25:c25:f004:113b
1592c19:dd:d9:dd:c25:c25:f004:113c/1272c19:dd:d9:dd:c25:c25:f004:113d
1602c19:dd:d9:dd:c25:c25:f004:113e/1272c19:dd:d9:dd:c25:c25:f004:113f
1612c19:dd:d9:dd:c25:c25:f004:1140/1272c19:dd:d9:dd:c25:c25:f004:1141
1622c19:dd:d9:dd:c25:c25:f004:1142/1272c19:dd:d9:dd:c25:c25:f004:1143
1632c19:dd:d9:dd:c25:c25:f004:1144/1272c19:dd:d9:dd:c25:c25:f004:1145
1642c19:dd:d9:dd:c25:c25:f004:1146/1272c19:dd:d9:dd:c25:c25:f004:1147
1652c19:dd:d9:dd:c25:c25:f004:1148/1272c19:dd:d9:dd:c25:c25:f004:1149
1662c19:dd:d9:dd:c25:c25:f004:114a/1272c19:dd:d9:dd:c25:c25:f004:114b
1672c19:dd:d9:dd:c25:c25:f004:114c/1272c19:dd:d9:dd:c25:c25:f004:114d
1682c19:dd:d9:dd:c25:c25:f004:114e/1272c19:dd:d9:dd:c25:c25:f004:114f
1692c19:dd:d9:dd:c25:c25:f004:1150/1272c19:dd:d9:dd:c25:c25:f004:1151
1702c19:dd:d9:dd:c25:c25:f004:1152/1272c19:dd:d9:dd:c25:c25:f004:1153
1712c19:dd:d9:dd:c25:c25:f004:1154/1272c19:dd:d9:dd:c25:c25:f004:1155
1722c19:dd:d9:dd:c25:c25:f004:1156/1272c19:dd:d9:dd:c25:c25:f004:1157
1732c19:dd:d9:dd:c25:c25:f004:1158/1272c19:dd:d9:dd:c25:c25:f004:1159
1742c19:dd:d9:dd:c25:c25:f004:115a/1272c19:dd:d9:dd:c25:c25:f004:115b
1752c19:dd:d9:dd:c25:c25:f004:115c/1272c19:dd:d9:dd:c25:c25:f004:115d
1762c19:dd:d9:dd:c25:c25:f004:115e/1272c19:dd:d9:dd:c25:c25:f004:115f
1772c19:dd:d9:dd:c25:c25:f004:1160/1272c19:dd:d9:dd:c25:c25:f004:1161
1782c19:dd:d9:dd:c25:c25:f004:1162/1272c19:dd:d9:dd:c25:c25:f004:1163
1792c19:dd:d9:dd:c25:c25:f004:1164/1272c19:dd:d9:dd:c25:c25:f004:1165
1802c19:dd:d9:dd:c25:c25:f004:1166/1272c19:dd:d9:dd:c25:c25:f004:1167
1812c19:dd:d9:dd:c25:c25:f004:1168/1272c19:dd:d9:dd:c25:c25:f004:1169
1822c19:dd:d9:dd:c25:c25:f004:116a/1272c19:dd:d9:dd:c25:c25:f004:116b
1832c19:dd:d9:dd:c25:c25:f004:116c/1272c19:dd:d9:dd:c25:c25:f004:116d
1842c19:dd:d9:dd:c25:c25:f004:116e/1272c19:dd:d9:dd:c25:c25:f004:116f
1852c19:dd:d9:dd:c25:c25:f004:1170/1272c19:dd:d9:dd:c25:c25:f004:1171
1862c19:dd:d9:dd:c25:c25:f004:1172/1272c19:dd:d9:dd:c25:c25:f004:1173
1872c19:dd:d9:dd:c25:c25:f004:1174/1272c19:dd:d9:dd:c25:c25:f004:1175
1882c19:dd:d9:dd:c25:c25:f004:1176/1272c19:dd:d9:dd:c25:c25:f004:1177
1892c19:dd:d9:dd:c25:c25:f004:1178/1272c19:dd:d9:dd:c25:c25:f004:1179
1902c19:dd:d9:dd:c25:c25:f004:117a/1272c19:dd:d9:dd:c25:c25:f004:117b
1912c19:dd:d9:dd:c25:c25:f004:117c/1272c19:dd:d9:dd:c25:c25:f004:117d
1922c19:dd:d9:dd:c25:c25:f004:117e/1272c19:dd:d9:dd:c25:c25:f004:117f
1932c19:dd:d9:dd:c25:c25:f004:1180/1272c19:dd:d9:dd:c25:c25:f004:1181
1942c19:dd:d9:dd:c25:c25:f004:1182/1272c19:dd:d9:dd:c25:c25:f004:1183
1952c19:dd:d9:dd:c25:c25:f004:1184/1272c19:dd:d9:dd:c25:c25:f004:1185
1962c19:dd:d9:dd:c25:c25:f004:1186/1272c19:dd:d9:dd:c25:c25:f004:1187
1972c19:dd:d9:dd:c25:c25:f004:1188/1272c19:dd:d9:dd:c25:c25:f004:1189
1982c19:dd:d9:dd:c25:c25:f004:118a/1272c19:dd:d9:dd:c25:c25:f004:118b
1992c19:dd:d9:dd:c25:c25:f004:118c/1272c19:dd:d9:dd:c25:c25:f004:118d
2002c19:dd:d9:dd:c25:c25:f004:118e/1272c19:dd:d9:dd:c25:c25:f004:118f
2012c19:dd:d9:dd:c25:c25:f004:1190/1272c19:dd:d9:dd:c25:c25:f004:1191
2022c19:dd:d9:dd:c25:c25:f004:1192/1272c19:dd:d9:dd:c25:c25:f004:1193
2032c19:dd:d9:dd:c25:c25:f004:1194/1272c19:dd:d9:dd:c25:c25:f004:1195
2042c19:dd:d9:dd:c25:c25:f004:1196/1272c19:dd:d9:dd:c25:c25:f004:1197
2052c19:dd:d9:dd:c25:c25:f004:1198/1272c19:dd:d9:dd:c25:c25:f004:1199
2062c19:dd:d9:dd:c25:c25:f004:119a/1272c19:dd:d9:dd:c25:c25:f004:119b
2072c19:dd:d9:dd:c25:c25:f004:119c/1272c19:dd:d9:dd:c25:c25:f004:119d
2082c19:dd:d9:dd:c25:c25:f004:119e/1272c19:dd:d9:dd:c25:c25:f004:119f
2092c19:dd:d9:dd:c25:c25:f004:11a0/1272c19:dd:d9:dd:c25:c25:f004:11a1
2102c19:dd:d9:dd:c25:c25:f004:11a2/1272c19:dd:d9:dd:c25:c25:f004:11a3
2112c19:dd:d9:dd:c25:c25:f004:11a4/1272c19:dd:d9:dd:c25:c25:f004:11a5
2122c19:dd:d9:dd:c25:c25:f004:11a6/1272c19:dd:d9:dd:c25:c25:f004:11a7
2132c19:dd:d9:dd:c25:c25:f004:11a8/1272c19:dd:d9:dd:c25:c25:f004:11a9
2142c19:dd:d9:dd:c25:c25:f004:11aa/1272c19:dd:d9:dd:c25:c25:f004:11ab
2152c19:dd:d9:dd:c25:c25:f004:11ac/1272c19:dd:d9:dd:c25:c25:f004:11ad
2162c19:dd:d9:dd:c25:c25:f004:11ae/1272c19:dd:d9:dd:c25:c25:f004:11af
2172c19:dd:d9:dd:c25:c25:f004:11b0/1272c19:dd:d9:dd:c25:c25:f004:11b1
2182c19:dd:d9:dd:c25:c25:f004:11b2/1272c19:dd:d9:dd:c25:c25:f004:11b3
2192c19:dd:d9:dd:c25:c25:f004:11b4/1272c19:dd:d9:dd:c25:c25:f004:11b5
2202c19:dd:d9:dd:c25:c25:f004:11b6/1272c19:dd:d9:dd:c25:c25:f004:11b7
2212c19:dd:d9:dd:c25:c25:f004:11b8/1272c19:dd:d9:dd:c25:c25:f004:11b9
2222c19:dd:d9:dd:c25:c25:f004:11ba/1272c19:dd:d9:dd:c25:c25:f004:11bb
2232c19:dd:d9:dd:c25:c25:f004:11bc/1272c19:dd:d9:dd:c25:c25:f004:11bd
2242c19:dd:d9:dd:c25:c25:f004:11be/1272c19:dd:d9:dd:c25:c25:f004:11bf
2252c19:dd:d9:dd:c25:c25:f004:11c0/1272c19:dd:d9:dd:c25:c25:f004:11c1
2262c19:dd:d9:dd:c25:c25:f004:11c2/1272c19:dd:d9:dd:c25:c25:f004:11c3
2272c19:dd:d9:dd:c25:c25:f004:11c4/1272c19:dd:d9:dd:c25:c25:f004:11c5
2282c19:dd:d9:dd:c25:c25:f004:11c6/1272c19:dd:d9:dd:c25:c25:f004:11c7
2292c19:dd:d9:dd:c25:c25:f004:11c8/1272c19:dd:d9:dd:c25:c25:f004:11c9
2302c19:dd:d9:dd:c25:c25:f004:11ca/1272c19:dd:d9:dd:c25:c25:f004:11cb
2312c19:dd:d9:dd:c25:c25:f004:11cc/1272c19:dd:d9:dd:c25:c25:f004:11cd
2322c19:dd:d9:dd:c25:c25:f004:11ce/1272c19:dd:d9:dd:c25:c25:f004:11cf
2332c19:dd:d9:dd:c25:c25:f004:11d0/1272c19:dd:d9:dd:c25:c25:f004:11d1
2342c19:dd:d9:dd:c25:c25:f004:11d2/1272c19:dd:d9:dd:c25:c25:f004:11d3
2352c19:dd:d9:dd:c25:c25:f004:11d4/1272c19:dd:d9:dd:c25:c25:f004:11d5
2362c19:dd:d9:dd:c25:c25:f004:11d6/1272c19:dd:d9:dd:c25:c25:f004:11d7
2372c19:dd:d9:dd:c25:c25:f004:11d8/1272c19:dd:d9:dd:c25:c25:f004:11d9
2382c19:dd:d9:dd:c25:c25:f004:11da/1272c19:dd:d9:dd:c25:c25:f004:11db
2392c19:dd:d9:dd:c25:c25:f004:11dc/1272c19:dd:d9:dd:c25:c25:f004:11dd
2402c19:dd:d9:dd:c25:c25:f004:11de/1272c19:dd:d9:dd:c25:c25:f004:11df
2412c19:dd:d9:dd:c25:c25:f004:11e0/1272c19:dd:d9:dd:c25:c25:f004:11e1
2422c19:dd:d9:dd:c25:c25:f004:11e2/1272c19:dd:d9:dd:c25:c25:f004:11e3
2432c19:dd:d9:dd:c25:c25:f004:11e4/1272c19:dd:d9:dd:c25:c25:f004:11e5
2442c19:dd:d9:dd:c25:c25:f004:11e6/1272c19:dd:d9:dd:c25:c25:f004:11e7
2452c19:dd:d9:dd:c25:c25:f004:11e8/1272c19:dd:d9:dd:c25:c25:f004:11e9
2462c19:dd:d9:dd:c25:c25:f004:11ea/1272c19:dd:d9:dd:c25:c25:f004:11eb
2472c19:dd:d9:dd:c25:c25:f004:11ec/1272c19:dd:d9:dd:c25:c25:f004:11ed
2482c19:dd:d9:dd:c25:c25:f004:11ee/1272c19:dd:d9:dd:c25:c25:f004:11ef
2492c19:dd:d9:dd:c25:c25:f004:11f0/1272c19:dd:d9:dd:c25:c25:f004:11f1
2502c19:dd:d9:dd:c25:c25:f004:11f2/1272c19:dd:d9:dd:c25:c25:f004:11f3
2512c19:dd:d9:dd:c25:c25:f004:11f4/1272c19:dd:d9:dd:c25:c25:f004:11f5
2522c19:dd:d9:dd:c25:c25:f004:11f6/1272c19:dd:d9:dd:c25:c25:f004:11f7
2532c19:dd:d9:dd:c25:c25:f004:11f8/1272c19:dd:d9:dd:c25:c25:f004:11f9
2542c19:dd:d9:dd:c25:c25:f004:11fa/1272c19:dd:d9:dd:c25:c25:f004:11fb
2552c19:dd:d9:dd:c25:c25:f004:11fc/1272c19:dd:d9:dd:c25:c25:f004:11fd
2562c19:dd:d9:dd:c25:c25:f004:11fe/1272c19:dd:d9:dd:c25:c25:f004:11ff

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.