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:c25:700c:4000/116
First address
2c19:dd:d9:dd:c25:c25:700c:4000
Last address
2c19:dd:d9:dd:c25:c25:700c:4fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:700c:4000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
4.c.0.0.7.5.2.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/128
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2c19:dd:d9:dd:c25:c25:700c:4000/116 makes 4,096 subnets of /128; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:700c:4000/1282c19:dd:d9:dd:c25:c25:700c:4000
22c19:dd:d9:dd:c25:c25:700c:4001/1282c19:dd:d9:dd:c25:c25:700c:4001
32c19:dd:d9:dd:c25:c25:700c:4002/1282c19:dd:d9:dd:c25:c25:700c:4002
42c19:dd:d9:dd:c25:c25:700c:4003/1282c19:dd:d9:dd:c25:c25:700c:4003
52c19:dd:d9:dd:c25:c25:700c:4004/1282c19:dd:d9:dd:c25:c25:700c:4004
62c19:dd:d9:dd:c25:c25:700c:4005/1282c19:dd:d9:dd:c25:c25:700c:4005
72c19:dd:d9:dd:c25:c25:700c:4006/1282c19:dd:d9:dd:c25:c25:700c:4006
82c19:dd:d9:dd:c25:c25:700c:4007/1282c19:dd:d9:dd:c25:c25:700c:4007
92c19:dd:d9:dd:c25:c25:700c:4008/1282c19:dd:d9:dd:c25:c25:700c:4008
102c19:dd:d9:dd:c25:c25:700c:4009/1282c19:dd:d9:dd:c25:c25:700c:4009
112c19:dd:d9:dd:c25:c25:700c:400a/1282c19:dd:d9:dd:c25:c25:700c:400a
122c19:dd:d9:dd:c25:c25:700c:400b/1282c19:dd:d9:dd:c25:c25:700c:400b
132c19:dd:d9:dd:c25:c25:700c:400c/1282c19:dd:d9:dd:c25:c25:700c:400c
142c19:dd:d9:dd:c25:c25:700c:400d/1282c19:dd:d9:dd:c25:c25:700c:400d
152c19:dd:d9:dd:c25:c25:700c:400e/1282c19:dd:d9:dd:c25:c25:700c:400e
162c19:dd:d9:dd:c25:c25:700c:400f/1282c19:dd:d9:dd:c25:c25:700c:400f
172c19:dd:d9:dd:c25:c25:700c:4010/1282c19:dd:d9:dd:c25:c25:700c:4010
182c19:dd:d9:dd:c25:c25:700c:4011/1282c19:dd:d9:dd:c25:c25:700c:4011
192c19:dd:d9:dd:c25:c25:700c:4012/1282c19:dd:d9:dd:c25:c25:700c:4012
202c19:dd:d9:dd:c25:c25:700c:4013/1282c19:dd:d9:dd:c25:c25:700c:4013
212c19:dd:d9:dd:c25:c25:700c:4014/1282c19:dd:d9:dd:c25:c25:700c:4014
222c19:dd:d9:dd:c25:c25:700c:4015/1282c19:dd:d9:dd:c25:c25:700c:4015
232c19:dd:d9:dd:c25:c25:700c:4016/1282c19:dd:d9:dd:c25:c25:700c:4016
242c19:dd:d9:dd:c25:c25:700c:4017/1282c19:dd:d9:dd:c25:c25:700c:4017
252c19:dd:d9:dd:c25:c25:700c:4018/1282c19:dd:d9:dd:c25:c25:700c:4018
262c19:dd:d9:dd:c25:c25:700c:4019/1282c19:dd:d9:dd:c25:c25:700c:4019
272c19:dd:d9:dd:c25:c25:700c:401a/1282c19:dd:d9:dd:c25:c25:700c:401a
282c19:dd:d9:dd:c25:c25:700c:401b/1282c19:dd:d9:dd:c25:c25:700c:401b
292c19:dd:d9:dd:c25:c25:700c:401c/1282c19:dd:d9:dd:c25:c25:700c:401c
302c19:dd:d9:dd:c25:c25:700c:401d/1282c19:dd:d9:dd:c25:c25:700c:401d
312c19:dd:d9:dd:c25:c25:700c:401e/1282c19:dd:d9:dd:c25:c25:700c:401e
322c19:dd:d9:dd:c25:c25:700c:401f/1282c19:dd:d9:dd:c25:c25:700c:401f
332c19:dd:d9:dd:c25:c25:700c:4020/1282c19:dd:d9:dd:c25:c25:700c:4020
342c19:dd:d9:dd:c25:c25:700c:4021/1282c19:dd:d9:dd:c25:c25:700c:4021
352c19:dd:d9:dd:c25:c25:700c:4022/1282c19:dd:d9:dd:c25:c25:700c:4022
362c19:dd:d9:dd:c25:c25:700c:4023/1282c19:dd:d9:dd:c25:c25:700c:4023
372c19:dd:d9:dd:c25:c25:700c:4024/1282c19:dd:d9:dd:c25:c25:700c:4024
382c19:dd:d9:dd:c25:c25:700c:4025/1282c19:dd:d9:dd:c25:c25:700c:4025
392c19:dd:d9:dd:c25:c25:700c:4026/1282c19:dd:d9:dd:c25:c25:700c:4026
402c19:dd:d9:dd:c25:c25:700c:4027/1282c19:dd:d9:dd:c25:c25:700c:4027
412c19:dd:d9:dd:c25:c25:700c:4028/1282c19:dd:d9:dd:c25:c25:700c:4028
422c19:dd:d9:dd:c25:c25:700c:4029/1282c19:dd:d9:dd:c25:c25:700c:4029
432c19:dd:d9:dd:c25:c25:700c:402a/1282c19:dd:d9:dd:c25:c25:700c:402a
442c19:dd:d9:dd:c25:c25:700c:402b/1282c19:dd:d9:dd:c25:c25:700c:402b
452c19:dd:d9:dd:c25:c25:700c:402c/1282c19:dd:d9:dd:c25:c25:700c:402c
462c19:dd:d9:dd:c25:c25:700c:402d/1282c19:dd:d9:dd:c25:c25:700c:402d
472c19:dd:d9:dd:c25:c25:700c:402e/1282c19:dd:d9:dd:c25:c25:700c:402e
482c19:dd:d9:dd:c25:c25:700c:402f/1282c19:dd:d9:dd:c25:c25:700c:402f
492c19:dd:d9:dd:c25:c25:700c:4030/1282c19:dd:d9:dd:c25:c25:700c:4030
502c19:dd:d9:dd:c25:c25:700c:4031/1282c19:dd:d9:dd:c25:c25:700c:4031
512c19:dd:d9:dd:c25:c25:700c:4032/1282c19:dd:d9:dd:c25:c25:700c:4032
522c19:dd:d9:dd:c25:c25:700c:4033/1282c19:dd:d9:dd:c25:c25:700c:4033
532c19:dd:d9:dd:c25:c25:700c:4034/1282c19:dd:d9:dd:c25:c25:700c:4034
542c19:dd:d9:dd:c25:c25:700c:4035/1282c19:dd:d9:dd:c25:c25:700c:4035
552c19:dd:d9:dd:c25:c25:700c:4036/1282c19:dd:d9:dd:c25:c25:700c:4036
562c19:dd:d9:dd:c25:c25:700c:4037/1282c19:dd:d9:dd:c25:c25:700c:4037
572c19:dd:d9:dd:c25:c25:700c:4038/1282c19:dd:d9:dd:c25:c25:700c:4038
582c19:dd:d9:dd:c25:c25:700c:4039/1282c19:dd:d9:dd:c25:c25:700c:4039
592c19:dd:d9:dd:c25:c25:700c:403a/1282c19:dd:d9:dd:c25:c25:700c:403a
602c19:dd:d9:dd:c25:c25:700c:403b/1282c19:dd:d9:dd:c25:c25:700c:403b
612c19:dd:d9:dd:c25:c25:700c:403c/1282c19:dd:d9:dd:c25:c25:700c:403c
622c19:dd:d9:dd:c25:c25:700c:403d/1282c19:dd:d9:dd:c25:c25:700c:403d
632c19:dd:d9:dd:c25:c25:700c:403e/1282c19:dd:d9:dd:c25:c25:700c:403e
642c19:dd:d9:dd:c25:c25:700c:403f/1282c19:dd:d9:dd:c25:c25:700c:403f
652c19:dd:d9:dd:c25:c25:700c:4040/1282c19:dd:d9:dd:c25:c25:700c:4040
662c19:dd:d9:dd:c25:c25:700c:4041/1282c19:dd:d9:dd:c25:c25:700c:4041
672c19:dd:d9:dd:c25:c25:700c:4042/1282c19:dd:d9:dd:c25:c25:700c:4042
682c19:dd:d9:dd:c25:c25:700c:4043/1282c19:dd:d9:dd:c25:c25:700c:4043
692c19:dd:d9:dd:c25:c25:700c:4044/1282c19:dd:d9:dd:c25:c25:700c:4044
702c19:dd:d9:dd:c25:c25:700c:4045/1282c19:dd:d9:dd:c25:c25:700c:4045
712c19:dd:d9:dd:c25:c25:700c:4046/1282c19:dd:d9:dd:c25:c25:700c:4046
722c19:dd:d9:dd:c25:c25:700c:4047/1282c19:dd:d9:dd:c25:c25:700c:4047
732c19:dd:d9:dd:c25:c25:700c:4048/1282c19:dd:d9:dd:c25:c25:700c:4048
742c19:dd:d9:dd:c25:c25:700c:4049/1282c19:dd:d9:dd:c25:c25:700c:4049
752c19:dd:d9:dd:c25:c25:700c:404a/1282c19:dd:d9:dd:c25:c25:700c:404a
762c19:dd:d9:dd:c25:c25:700c:404b/1282c19:dd:d9:dd:c25:c25:700c:404b
772c19:dd:d9:dd:c25:c25:700c:404c/1282c19:dd:d9:dd:c25:c25:700c:404c
782c19:dd:d9:dd:c25:c25:700c:404d/1282c19:dd:d9:dd:c25:c25:700c:404d
792c19:dd:d9:dd:c25:c25:700c:404e/1282c19:dd:d9:dd:c25:c25:700c:404e
802c19:dd:d9:dd:c25:c25:700c:404f/1282c19:dd:d9:dd:c25:c25:700c:404f
812c19:dd:d9:dd:c25:c25:700c:4050/1282c19:dd:d9:dd:c25:c25:700c:4050
822c19:dd:d9:dd:c25:c25:700c:4051/1282c19:dd:d9:dd:c25:c25:700c:4051
832c19:dd:d9:dd:c25:c25:700c:4052/1282c19:dd:d9:dd:c25:c25:700c:4052
842c19:dd:d9:dd:c25:c25:700c:4053/1282c19:dd:d9:dd:c25:c25:700c:4053
852c19:dd:d9:dd:c25:c25:700c:4054/1282c19:dd:d9:dd:c25:c25:700c:4054
862c19:dd:d9:dd:c25:c25:700c:4055/1282c19:dd:d9:dd:c25:c25:700c:4055
872c19:dd:d9:dd:c25:c25:700c:4056/1282c19:dd:d9:dd:c25:c25:700c:4056
882c19:dd:d9:dd:c25:c25:700c:4057/1282c19:dd:d9:dd:c25:c25:700c:4057
892c19:dd:d9:dd:c25:c25:700c:4058/1282c19:dd:d9:dd:c25:c25:700c:4058
902c19:dd:d9:dd:c25:c25:700c:4059/1282c19:dd:d9:dd:c25:c25:700c:4059
912c19:dd:d9:dd:c25:c25:700c:405a/1282c19:dd:d9:dd:c25:c25:700c:405a
922c19:dd:d9:dd:c25:c25:700c:405b/1282c19:dd:d9:dd:c25:c25:700c:405b
932c19:dd:d9:dd:c25:c25:700c:405c/1282c19:dd:d9:dd:c25:c25:700c:405c
942c19:dd:d9:dd:c25:c25:700c:405d/1282c19:dd:d9:dd:c25:c25:700c:405d
952c19:dd:d9:dd:c25:c25:700c:405e/1282c19:dd:d9:dd:c25:c25:700c:405e
962c19:dd:d9:dd:c25:c25:700c:405f/1282c19:dd:d9:dd:c25:c25:700c:405f
972c19:dd:d9:dd:c25:c25:700c:4060/1282c19:dd:d9:dd:c25:c25:700c:4060
982c19:dd:d9:dd:c25:c25:700c:4061/1282c19:dd:d9:dd:c25:c25:700c:4061
992c19:dd:d9:dd:c25:c25:700c:4062/1282c19:dd:d9:dd:c25:c25:700c:4062
1002c19:dd:d9:dd:c25:c25:700c:4063/1282c19:dd:d9:dd:c25:c25:700c:4063
1012c19:dd:d9:dd:c25:c25:700c:4064/1282c19:dd:d9:dd:c25:c25:700c:4064
1022c19:dd:d9:dd:c25:c25:700c:4065/1282c19:dd:d9:dd:c25:c25:700c:4065
1032c19:dd:d9:dd:c25:c25:700c:4066/1282c19:dd:d9:dd:c25:c25:700c:4066
1042c19:dd:d9:dd:c25:c25:700c:4067/1282c19:dd:d9:dd:c25:c25:700c:4067
1052c19:dd:d9:dd:c25:c25:700c:4068/1282c19:dd:d9:dd:c25:c25:700c:4068
1062c19:dd:d9:dd:c25:c25:700c:4069/1282c19:dd:d9:dd:c25:c25:700c:4069
1072c19:dd:d9:dd:c25:c25:700c:406a/1282c19:dd:d9:dd:c25:c25:700c:406a
1082c19:dd:d9:dd:c25:c25:700c:406b/1282c19:dd:d9:dd:c25:c25:700c:406b
1092c19:dd:d9:dd:c25:c25:700c:406c/1282c19:dd:d9:dd:c25:c25:700c:406c
1102c19:dd:d9:dd:c25:c25:700c:406d/1282c19:dd:d9:dd:c25:c25:700c:406d
1112c19:dd:d9:dd:c25:c25:700c:406e/1282c19:dd:d9:dd:c25:c25:700c:406e
1122c19:dd:d9:dd:c25:c25:700c:406f/1282c19:dd:d9:dd:c25:c25:700c:406f
1132c19:dd:d9:dd:c25:c25:700c:4070/1282c19:dd:d9:dd:c25:c25:700c:4070
1142c19:dd:d9:dd:c25:c25:700c:4071/1282c19:dd:d9:dd:c25:c25:700c:4071
1152c19:dd:d9:dd:c25:c25:700c:4072/1282c19:dd:d9:dd:c25:c25:700c:4072
1162c19:dd:d9:dd:c25:c25:700c:4073/1282c19:dd:d9:dd:c25:c25:700c:4073
1172c19:dd:d9:dd:c25:c25:700c:4074/1282c19:dd:d9:dd:c25:c25:700c:4074
1182c19:dd:d9:dd:c25:c25:700c:4075/1282c19:dd:d9:dd:c25:c25:700c:4075
1192c19:dd:d9:dd:c25:c25:700c:4076/1282c19:dd:d9:dd:c25:c25:700c:4076
1202c19:dd:d9:dd:c25:c25:700c:4077/1282c19:dd:d9:dd:c25:c25:700c:4077
1212c19:dd:d9:dd:c25:c25:700c:4078/1282c19:dd:d9:dd:c25:c25:700c:4078
1222c19:dd:d9:dd:c25:c25:700c:4079/1282c19:dd:d9:dd:c25:c25:700c:4079
1232c19:dd:d9:dd:c25:c25:700c:407a/1282c19:dd:d9:dd:c25:c25:700c:407a
1242c19:dd:d9:dd:c25:c25:700c:407b/1282c19:dd:d9:dd:c25:c25:700c:407b
1252c19:dd:d9:dd:c25:c25:700c:407c/1282c19:dd:d9:dd:c25:c25:700c:407c
1262c19:dd:d9:dd:c25:c25:700c:407d/1282c19:dd:d9:dd:c25:c25:700c:407d
1272c19:dd:d9:dd:c25:c25:700c:407e/1282c19:dd:d9:dd:c25:c25:700c:407e
1282c19:dd:d9:dd:c25:c25:700c:407f/1282c19:dd:d9:dd:c25:c25:700c:407f
1292c19:dd:d9:dd:c25:c25:700c:4080/1282c19:dd:d9:dd:c25:c25:700c:4080
1302c19:dd:d9:dd:c25:c25:700c:4081/1282c19:dd:d9:dd:c25:c25:700c:4081
1312c19:dd:d9:dd:c25:c25:700c:4082/1282c19:dd:d9:dd:c25:c25:700c:4082
1322c19:dd:d9:dd:c25:c25:700c:4083/1282c19:dd:d9:dd:c25:c25:700c:4083
1332c19:dd:d9:dd:c25:c25:700c:4084/1282c19:dd:d9:dd:c25:c25:700c:4084
1342c19:dd:d9:dd:c25:c25:700c:4085/1282c19:dd:d9:dd:c25:c25:700c:4085
1352c19:dd:d9:dd:c25:c25:700c:4086/1282c19:dd:d9:dd:c25:c25:700c:4086
1362c19:dd:d9:dd:c25:c25:700c:4087/1282c19:dd:d9:dd:c25:c25:700c:4087
1372c19:dd:d9:dd:c25:c25:700c:4088/1282c19:dd:d9:dd:c25:c25:700c:4088
1382c19:dd:d9:dd:c25:c25:700c:4089/1282c19:dd:d9:dd:c25:c25:700c:4089
1392c19:dd:d9:dd:c25:c25:700c:408a/1282c19:dd:d9:dd:c25:c25:700c:408a
1402c19:dd:d9:dd:c25:c25:700c:408b/1282c19:dd:d9:dd:c25:c25:700c:408b
1412c19:dd:d9:dd:c25:c25:700c:408c/1282c19:dd:d9:dd:c25:c25:700c:408c
1422c19:dd:d9:dd:c25:c25:700c:408d/1282c19:dd:d9:dd:c25:c25:700c:408d
1432c19:dd:d9:dd:c25:c25:700c:408e/1282c19:dd:d9:dd:c25:c25:700c:408e
1442c19:dd:d9:dd:c25:c25:700c:408f/1282c19:dd:d9:dd:c25:c25:700c:408f
1452c19:dd:d9:dd:c25:c25:700c:4090/1282c19:dd:d9:dd:c25:c25:700c:4090
1462c19:dd:d9:dd:c25:c25:700c:4091/1282c19:dd:d9:dd:c25:c25:700c:4091
1472c19:dd:d9:dd:c25:c25:700c:4092/1282c19:dd:d9:dd:c25:c25:700c:4092
1482c19:dd:d9:dd:c25:c25:700c:4093/1282c19:dd:d9:dd:c25:c25:700c:4093
1492c19:dd:d9:dd:c25:c25:700c:4094/1282c19:dd:d9:dd:c25:c25:700c:4094
1502c19:dd:d9:dd:c25:c25:700c:4095/1282c19:dd:d9:dd:c25:c25:700c:4095
1512c19:dd:d9:dd:c25:c25:700c:4096/1282c19:dd:d9:dd:c25:c25:700c:4096
1522c19:dd:d9:dd:c25:c25:700c:4097/1282c19:dd:d9:dd:c25:c25:700c:4097
1532c19:dd:d9:dd:c25:c25:700c:4098/1282c19:dd:d9:dd:c25:c25:700c:4098
1542c19:dd:d9:dd:c25:c25:700c:4099/1282c19:dd:d9:dd:c25:c25:700c:4099
1552c19:dd:d9:dd:c25:c25:700c:409a/1282c19:dd:d9:dd:c25:c25:700c:409a
1562c19:dd:d9:dd:c25:c25:700c:409b/1282c19:dd:d9:dd:c25:c25:700c:409b
1572c19:dd:d9:dd:c25:c25:700c:409c/1282c19:dd:d9:dd:c25:c25:700c:409c
1582c19:dd:d9:dd:c25:c25:700c:409d/1282c19:dd:d9:dd:c25:c25:700c:409d
1592c19:dd:d9:dd:c25:c25:700c:409e/1282c19:dd:d9:dd:c25:c25:700c:409e
1602c19:dd:d9:dd:c25:c25:700c:409f/1282c19:dd:d9:dd:c25:c25:700c:409f
1612c19:dd:d9:dd:c25:c25:700c:40a0/1282c19:dd:d9:dd:c25:c25:700c:40a0
1622c19:dd:d9:dd:c25:c25:700c:40a1/1282c19:dd:d9:dd:c25:c25:700c:40a1
1632c19:dd:d9:dd:c25:c25:700c:40a2/1282c19:dd:d9:dd:c25:c25:700c:40a2
1642c19:dd:d9:dd:c25:c25:700c:40a3/1282c19:dd:d9:dd:c25:c25:700c:40a3
1652c19:dd:d9:dd:c25:c25:700c:40a4/1282c19:dd:d9:dd:c25:c25:700c:40a4
1662c19:dd:d9:dd:c25:c25:700c:40a5/1282c19:dd:d9:dd:c25:c25:700c:40a5
1672c19:dd:d9:dd:c25:c25:700c:40a6/1282c19:dd:d9:dd:c25:c25:700c:40a6
1682c19:dd:d9:dd:c25:c25:700c:40a7/1282c19:dd:d9:dd:c25:c25:700c:40a7
1692c19:dd:d9:dd:c25:c25:700c:40a8/1282c19:dd:d9:dd:c25:c25:700c:40a8
1702c19:dd:d9:dd:c25:c25:700c:40a9/1282c19:dd:d9:dd:c25:c25:700c:40a9
1712c19:dd:d9:dd:c25:c25:700c:40aa/1282c19:dd:d9:dd:c25:c25:700c:40aa
1722c19:dd:d9:dd:c25:c25:700c:40ab/1282c19:dd:d9:dd:c25:c25:700c:40ab
1732c19:dd:d9:dd:c25:c25:700c:40ac/1282c19:dd:d9:dd:c25:c25:700c:40ac
1742c19:dd:d9:dd:c25:c25:700c:40ad/1282c19:dd:d9:dd:c25:c25:700c:40ad
1752c19:dd:d9:dd:c25:c25:700c:40ae/1282c19:dd:d9:dd:c25:c25:700c:40ae
1762c19:dd:d9:dd:c25:c25:700c:40af/1282c19:dd:d9:dd:c25:c25:700c:40af
1772c19:dd:d9:dd:c25:c25:700c:40b0/1282c19:dd:d9:dd:c25:c25:700c:40b0
1782c19:dd:d9:dd:c25:c25:700c:40b1/1282c19:dd:d9:dd:c25:c25:700c:40b1
1792c19:dd:d9:dd:c25:c25:700c:40b2/1282c19:dd:d9:dd:c25:c25:700c:40b2
1802c19:dd:d9:dd:c25:c25:700c:40b3/1282c19:dd:d9:dd:c25:c25:700c:40b3
1812c19:dd:d9:dd:c25:c25:700c:40b4/1282c19:dd:d9:dd:c25:c25:700c:40b4
1822c19:dd:d9:dd:c25:c25:700c:40b5/1282c19:dd:d9:dd:c25:c25:700c:40b5
1832c19:dd:d9:dd:c25:c25:700c:40b6/1282c19:dd:d9:dd:c25:c25:700c:40b6
1842c19:dd:d9:dd:c25:c25:700c:40b7/1282c19:dd:d9:dd:c25:c25:700c:40b7
1852c19:dd:d9:dd:c25:c25:700c:40b8/1282c19:dd:d9:dd:c25:c25:700c:40b8
1862c19:dd:d9:dd:c25:c25:700c:40b9/1282c19:dd:d9:dd:c25:c25:700c:40b9
1872c19:dd:d9:dd:c25:c25:700c:40ba/1282c19:dd:d9:dd:c25:c25:700c:40ba
1882c19:dd:d9:dd:c25:c25:700c:40bb/1282c19:dd:d9:dd:c25:c25:700c:40bb
1892c19:dd:d9:dd:c25:c25:700c:40bc/1282c19:dd:d9:dd:c25:c25:700c:40bc
1902c19:dd:d9:dd:c25:c25:700c:40bd/1282c19:dd:d9:dd:c25:c25:700c:40bd
1912c19:dd:d9:dd:c25:c25:700c:40be/1282c19:dd:d9:dd:c25:c25:700c:40be
1922c19:dd:d9:dd:c25:c25:700c:40bf/1282c19:dd:d9:dd:c25:c25:700c:40bf
1932c19:dd:d9:dd:c25:c25:700c:40c0/1282c19:dd:d9:dd:c25:c25:700c:40c0
1942c19:dd:d9:dd:c25:c25:700c:40c1/1282c19:dd:d9:dd:c25:c25:700c:40c1
1952c19:dd:d9:dd:c25:c25:700c:40c2/1282c19:dd:d9:dd:c25:c25:700c:40c2
1962c19:dd:d9:dd:c25:c25:700c:40c3/1282c19:dd:d9:dd:c25:c25:700c:40c3
1972c19:dd:d9:dd:c25:c25:700c:40c4/1282c19:dd:d9:dd:c25:c25:700c:40c4
1982c19:dd:d9:dd:c25:c25:700c:40c5/1282c19:dd:d9:dd:c25:c25:700c:40c5
1992c19:dd:d9:dd:c25:c25:700c:40c6/1282c19:dd:d9:dd:c25:c25:700c:40c6
2002c19:dd:d9:dd:c25:c25:700c:40c7/1282c19:dd:d9:dd:c25:c25:700c:40c7
2012c19:dd:d9:dd:c25:c25:700c:40c8/1282c19:dd:d9:dd:c25:c25:700c:40c8
2022c19:dd:d9:dd:c25:c25:700c:40c9/1282c19:dd:d9:dd:c25:c25:700c:40c9
2032c19:dd:d9:dd:c25:c25:700c:40ca/1282c19:dd:d9:dd:c25:c25:700c:40ca
2042c19:dd:d9:dd:c25:c25:700c:40cb/1282c19:dd:d9:dd:c25:c25:700c:40cb
2052c19:dd:d9:dd:c25:c25:700c:40cc/1282c19:dd:d9:dd:c25:c25:700c:40cc
2062c19:dd:d9:dd:c25:c25:700c:40cd/1282c19:dd:d9:dd:c25:c25:700c:40cd
2072c19:dd:d9:dd:c25:c25:700c:40ce/1282c19:dd:d9:dd:c25:c25:700c:40ce
2082c19:dd:d9:dd:c25:c25:700c:40cf/1282c19:dd:d9:dd:c25:c25:700c:40cf
2092c19:dd:d9:dd:c25:c25:700c:40d0/1282c19:dd:d9:dd:c25:c25:700c:40d0
2102c19:dd:d9:dd:c25:c25:700c:40d1/1282c19:dd:d9:dd:c25:c25:700c:40d1
2112c19:dd:d9:dd:c25:c25:700c:40d2/1282c19:dd:d9:dd:c25:c25:700c:40d2
2122c19:dd:d9:dd:c25:c25:700c:40d3/1282c19:dd:d9:dd:c25:c25:700c:40d3
2132c19:dd:d9:dd:c25:c25:700c:40d4/1282c19:dd:d9:dd:c25:c25:700c:40d4
2142c19:dd:d9:dd:c25:c25:700c:40d5/1282c19:dd:d9:dd:c25:c25:700c:40d5
2152c19:dd:d9:dd:c25:c25:700c:40d6/1282c19:dd:d9:dd:c25:c25:700c:40d6
2162c19:dd:d9:dd:c25:c25:700c:40d7/1282c19:dd:d9:dd:c25:c25:700c:40d7
2172c19:dd:d9:dd:c25:c25:700c:40d8/1282c19:dd:d9:dd:c25:c25:700c:40d8
2182c19:dd:d9:dd:c25:c25:700c:40d9/1282c19:dd:d9:dd:c25:c25:700c:40d9
2192c19:dd:d9:dd:c25:c25:700c:40da/1282c19:dd:d9:dd:c25:c25:700c:40da
2202c19:dd:d9:dd:c25:c25:700c:40db/1282c19:dd:d9:dd:c25:c25:700c:40db
2212c19:dd:d9:dd:c25:c25:700c:40dc/1282c19:dd:d9:dd:c25:c25:700c:40dc
2222c19:dd:d9:dd:c25:c25:700c:40dd/1282c19:dd:d9:dd:c25:c25:700c:40dd
2232c19:dd:d9:dd:c25:c25:700c:40de/1282c19:dd:d9:dd:c25:c25:700c:40de
2242c19:dd:d9:dd:c25:c25:700c:40df/1282c19:dd:d9:dd:c25:c25:700c:40df
2252c19:dd:d9:dd:c25:c25:700c:40e0/1282c19:dd:d9:dd:c25:c25:700c:40e0
2262c19:dd:d9:dd:c25:c25:700c:40e1/1282c19:dd:d9:dd:c25:c25:700c:40e1
2272c19:dd:d9:dd:c25:c25:700c:40e2/1282c19:dd:d9:dd:c25:c25:700c:40e2
2282c19:dd:d9:dd:c25:c25:700c:40e3/1282c19:dd:d9:dd:c25:c25:700c:40e3
2292c19:dd:d9:dd:c25:c25:700c:40e4/1282c19:dd:d9:dd:c25:c25:700c:40e4
2302c19:dd:d9:dd:c25:c25:700c:40e5/1282c19:dd:d9:dd:c25:c25:700c:40e5
2312c19:dd:d9:dd:c25:c25:700c:40e6/1282c19:dd:d9:dd:c25:c25:700c:40e6
2322c19:dd:d9:dd:c25:c25:700c:40e7/1282c19:dd:d9:dd:c25:c25:700c:40e7
2332c19:dd:d9:dd:c25:c25:700c:40e8/1282c19:dd:d9:dd:c25:c25:700c:40e8
2342c19:dd:d9:dd:c25:c25:700c:40e9/1282c19:dd:d9:dd:c25:c25:700c:40e9
2352c19:dd:d9:dd:c25:c25:700c:40ea/1282c19:dd:d9:dd:c25:c25:700c:40ea
2362c19:dd:d9:dd:c25:c25:700c:40eb/1282c19:dd:d9:dd:c25:c25:700c:40eb
2372c19:dd:d9:dd:c25:c25:700c:40ec/1282c19:dd:d9:dd:c25:c25:700c:40ec
2382c19:dd:d9:dd:c25:c25:700c:40ed/1282c19:dd:d9:dd:c25:c25:700c:40ed
2392c19:dd:d9:dd:c25:c25:700c:40ee/1282c19:dd:d9:dd:c25:c25:700c:40ee
2402c19:dd:d9:dd:c25:c25:700c:40ef/1282c19:dd:d9:dd:c25:c25:700c:40ef
2412c19:dd:d9:dd:c25:c25:700c:40f0/1282c19:dd:d9:dd:c25:c25:700c:40f0
2422c19:dd:d9:dd:c25:c25:700c:40f1/1282c19:dd:d9:dd:c25:c25:700c:40f1
2432c19:dd:d9:dd:c25:c25:700c:40f2/1282c19:dd:d9:dd:c25:c25:700c:40f2
2442c19:dd:d9:dd:c25:c25:700c:40f3/1282c19:dd:d9:dd:c25:c25:700c:40f3
2452c19:dd:d9:dd:c25:c25:700c:40f4/1282c19:dd:d9:dd:c25:c25:700c:40f4
2462c19:dd:d9:dd:c25:c25:700c:40f5/1282c19:dd:d9:dd:c25:c25:700c:40f5
2472c19:dd:d9:dd:c25:c25:700c:40f6/1282c19:dd:d9:dd:c25:c25:700c:40f6
2482c19:dd:d9:dd:c25:c25:700c:40f7/1282c19:dd:d9:dd:c25:c25:700c:40f7
2492c19:dd:d9:dd:c25:c25:700c:40f8/1282c19:dd:d9:dd:c25:c25:700c:40f8
2502c19:dd:d9:dd:c25:c25:700c:40f9/1282c19:dd:d9:dd:c25:c25:700c:40f9
2512c19:dd:d9:dd:c25:c25:700c:40fa/1282c19:dd:d9:dd:c25:c25:700c:40fa
2522c19:dd:d9:dd:c25:c25:700c:40fb/1282c19:dd:d9:dd:c25:c25:700c:40fb
2532c19:dd:d9:dd:c25:c25:700c:40fc/1282c19:dd:d9:dd:c25:c25:700c:40fc
2542c19:dd:d9:dd:c25:c25:700c:40fd/1282c19:dd:d9:dd:c25:c25:700c:40fd
2552c19:dd:d9:dd:c25:c25:700c:40fe/1282c19:dd:d9:dd:c25:c25:700c:40fe
2562c19:dd:d9:dd:c25:c25:700c:40ff/1282c19:dd:d9:dd:c25:c25:700c:40ff

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.