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:dd0:ec00:c25:c25:dd6:d000/116
First address
2c19:dd:dd0:ec00:c25:c25:dd6:d000
Last address
2c19:dd:dd0:ec00:c25:c25:dd6:dfff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:0dd0:ec00:0c25:0c25:0dd6:d000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
d.6.d.d.0.5.2.c.0.5.2.c.0.0.0.c.e.0.d.d.0.d.d.0.0.9.1.c.2.ip6.arpa
Split into smaller subnets/124
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2c19:dd:dd0:ec00:c25:c25:dd6:d000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12c19:dd:dd0:ec00:c25:c25:dd6:d000/1242c19:dd:dd0:ec00:c25:c25:dd6:d00f
22c19:dd:dd0:ec00:c25:c25:dd6:d010/1242c19:dd:dd0:ec00:c25:c25:dd6:d01f
32c19:dd:dd0:ec00:c25:c25:dd6:d020/1242c19:dd:dd0:ec00:c25:c25:dd6:d02f
42c19:dd:dd0:ec00:c25:c25:dd6:d030/1242c19:dd:dd0:ec00:c25:c25:dd6:d03f
52c19:dd:dd0:ec00:c25:c25:dd6:d040/1242c19:dd:dd0:ec00:c25:c25:dd6:d04f
62c19:dd:dd0:ec00:c25:c25:dd6:d050/1242c19:dd:dd0:ec00:c25:c25:dd6:d05f
72c19:dd:dd0:ec00:c25:c25:dd6:d060/1242c19:dd:dd0:ec00:c25:c25:dd6:d06f
82c19:dd:dd0:ec00:c25:c25:dd6:d070/1242c19:dd:dd0:ec00:c25:c25:dd6:d07f
92c19:dd:dd0:ec00:c25:c25:dd6:d080/1242c19:dd:dd0:ec00:c25:c25:dd6:d08f
102c19:dd:dd0:ec00:c25:c25:dd6:d090/1242c19:dd:dd0:ec00:c25:c25:dd6:d09f
112c19:dd:dd0:ec00:c25:c25:dd6:d0a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d0af
122c19:dd:dd0:ec00:c25:c25:dd6:d0b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d0bf
132c19:dd:dd0:ec00:c25:c25:dd6:d0c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d0cf
142c19:dd:dd0:ec00:c25:c25:dd6:d0d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d0df
152c19:dd:dd0:ec00:c25:c25:dd6:d0e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d0ef
162c19:dd:dd0:ec00:c25:c25:dd6:d0f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d0ff
172c19:dd:dd0:ec00:c25:c25:dd6:d100/1242c19:dd:dd0:ec00:c25:c25:dd6:d10f
182c19:dd:dd0:ec00:c25:c25:dd6:d110/1242c19:dd:dd0:ec00:c25:c25:dd6:d11f
192c19:dd:dd0:ec00:c25:c25:dd6:d120/1242c19:dd:dd0:ec00:c25:c25:dd6:d12f
202c19:dd:dd0:ec00:c25:c25:dd6:d130/1242c19:dd:dd0:ec00:c25:c25:dd6:d13f
212c19:dd:dd0:ec00:c25:c25:dd6:d140/1242c19:dd:dd0:ec00:c25:c25:dd6:d14f
222c19:dd:dd0:ec00:c25:c25:dd6:d150/1242c19:dd:dd0:ec00:c25:c25:dd6:d15f
232c19:dd:dd0:ec00:c25:c25:dd6:d160/1242c19:dd:dd0:ec00:c25:c25:dd6:d16f
242c19:dd:dd0:ec00:c25:c25:dd6:d170/1242c19:dd:dd0:ec00:c25:c25:dd6:d17f
252c19:dd:dd0:ec00:c25:c25:dd6:d180/1242c19:dd:dd0:ec00:c25:c25:dd6:d18f
262c19:dd:dd0:ec00:c25:c25:dd6:d190/1242c19:dd:dd0:ec00:c25:c25:dd6:d19f
272c19:dd:dd0:ec00:c25:c25:dd6:d1a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d1af
282c19:dd:dd0:ec00:c25:c25:dd6:d1b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d1bf
292c19:dd:dd0:ec00:c25:c25:dd6:d1c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d1cf
302c19:dd:dd0:ec00:c25:c25:dd6:d1d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d1df
312c19:dd:dd0:ec00:c25:c25:dd6:d1e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d1ef
322c19:dd:dd0:ec00:c25:c25:dd6:d1f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d1ff
332c19:dd:dd0:ec00:c25:c25:dd6:d200/1242c19:dd:dd0:ec00:c25:c25:dd6:d20f
342c19:dd:dd0:ec00:c25:c25:dd6:d210/1242c19:dd:dd0:ec00:c25:c25:dd6:d21f
352c19:dd:dd0:ec00:c25:c25:dd6:d220/1242c19:dd:dd0:ec00:c25:c25:dd6:d22f
362c19:dd:dd0:ec00:c25:c25:dd6:d230/1242c19:dd:dd0:ec00:c25:c25:dd6:d23f
372c19:dd:dd0:ec00:c25:c25:dd6:d240/1242c19:dd:dd0:ec00:c25:c25:dd6:d24f
382c19:dd:dd0:ec00:c25:c25:dd6:d250/1242c19:dd:dd0:ec00:c25:c25:dd6:d25f
392c19:dd:dd0:ec00:c25:c25:dd6:d260/1242c19:dd:dd0:ec00:c25:c25:dd6:d26f
402c19:dd:dd0:ec00:c25:c25:dd6:d270/1242c19:dd:dd0:ec00:c25:c25:dd6:d27f
412c19:dd:dd0:ec00:c25:c25:dd6:d280/1242c19:dd:dd0:ec00:c25:c25:dd6:d28f
422c19:dd:dd0:ec00:c25:c25:dd6:d290/1242c19:dd:dd0:ec00:c25:c25:dd6:d29f
432c19:dd:dd0:ec00:c25:c25:dd6:d2a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d2af
442c19:dd:dd0:ec00:c25:c25:dd6:d2b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d2bf
452c19:dd:dd0:ec00:c25:c25:dd6:d2c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d2cf
462c19:dd:dd0:ec00:c25:c25:dd6:d2d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d2df
472c19:dd:dd0:ec00:c25:c25:dd6:d2e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d2ef
482c19:dd:dd0:ec00:c25:c25:dd6:d2f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d2ff
492c19:dd:dd0:ec00:c25:c25:dd6:d300/1242c19:dd:dd0:ec00:c25:c25:dd6:d30f
502c19:dd:dd0:ec00:c25:c25:dd6:d310/1242c19:dd:dd0:ec00:c25:c25:dd6:d31f
512c19:dd:dd0:ec00:c25:c25:dd6:d320/1242c19:dd:dd0:ec00:c25:c25:dd6:d32f
522c19:dd:dd0:ec00:c25:c25:dd6:d330/1242c19:dd:dd0:ec00:c25:c25:dd6:d33f
532c19:dd:dd0:ec00:c25:c25:dd6:d340/1242c19:dd:dd0:ec00:c25:c25:dd6:d34f
542c19:dd:dd0:ec00:c25:c25:dd6:d350/1242c19:dd:dd0:ec00:c25:c25:dd6:d35f
552c19:dd:dd0:ec00:c25:c25:dd6:d360/1242c19:dd:dd0:ec00:c25:c25:dd6:d36f
562c19:dd:dd0:ec00:c25:c25:dd6:d370/1242c19:dd:dd0:ec00:c25:c25:dd6:d37f
572c19:dd:dd0:ec00:c25:c25:dd6:d380/1242c19:dd:dd0:ec00:c25:c25:dd6:d38f
582c19:dd:dd0:ec00:c25:c25:dd6:d390/1242c19:dd:dd0:ec00:c25:c25:dd6:d39f
592c19:dd:dd0:ec00:c25:c25:dd6:d3a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d3af
602c19:dd:dd0:ec00:c25:c25:dd6:d3b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d3bf
612c19:dd:dd0:ec00:c25:c25:dd6:d3c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d3cf
622c19:dd:dd0:ec00:c25:c25:dd6:d3d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d3df
632c19:dd:dd0:ec00:c25:c25:dd6:d3e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d3ef
642c19:dd:dd0:ec00:c25:c25:dd6:d3f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d3ff
652c19:dd:dd0:ec00:c25:c25:dd6:d400/1242c19:dd:dd0:ec00:c25:c25:dd6:d40f
662c19:dd:dd0:ec00:c25:c25:dd6:d410/1242c19:dd:dd0:ec00:c25:c25:dd6:d41f
672c19:dd:dd0:ec00:c25:c25:dd6:d420/1242c19:dd:dd0:ec00:c25:c25:dd6:d42f
682c19:dd:dd0:ec00:c25:c25:dd6:d430/1242c19:dd:dd0:ec00:c25:c25:dd6:d43f
692c19:dd:dd0:ec00:c25:c25:dd6:d440/1242c19:dd:dd0:ec00:c25:c25:dd6:d44f
702c19:dd:dd0:ec00:c25:c25:dd6:d450/1242c19:dd:dd0:ec00:c25:c25:dd6:d45f
712c19:dd:dd0:ec00:c25:c25:dd6:d460/1242c19:dd:dd0:ec00:c25:c25:dd6:d46f
722c19:dd:dd0:ec00:c25:c25:dd6:d470/1242c19:dd:dd0:ec00:c25:c25:dd6:d47f
732c19:dd:dd0:ec00:c25:c25:dd6:d480/1242c19:dd:dd0:ec00:c25:c25:dd6:d48f
742c19:dd:dd0:ec00:c25:c25:dd6:d490/1242c19:dd:dd0:ec00:c25:c25:dd6:d49f
752c19:dd:dd0:ec00:c25:c25:dd6:d4a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d4af
762c19:dd:dd0:ec00:c25:c25:dd6:d4b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d4bf
772c19:dd:dd0:ec00:c25:c25:dd6:d4c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d4cf
782c19:dd:dd0:ec00:c25:c25:dd6:d4d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d4df
792c19:dd:dd0:ec00:c25:c25:dd6:d4e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d4ef
802c19:dd:dd0:ec00:c25:c25:dd6:d4f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d4ff
812c19:dd:dd0:ec00:c25:c25:dd6:d500/1242c19:dd:dd0:ec00:c25:c25:dd6:d50f
822c19:dd:dd0:ec00:c25:c25:dd6:d510/1242c19:dd:dd0:ec00:c25:c25:dd6:d51f
832c19:dd:dd0:ec00:c25:c25:dd6:d520/1242c19:dd:dd0:ec00:c25:c25:dd6:d52f
842c19:dd:dd0:ec00:c25:c25:dd6:d530/1242c19:dd:dd0:ec00:c25:c25:dd6:d53f
852c19:dd:dd0:ec00:c25:c25:dd6:d540/1242c19:dd:dd0:ec00:c25:c25:dd6:d54f
862c19:dd:dd0:ec00:c25:c25:dd6:d550/1242c19:dd:dd0:ec00:c25:c25:dd6:d55f
872c19:dd:dd0:ec00:c25:c25:dd6:d560/1242c19:dd:dd0:ec00:c25:c25:dd6:d56f
882c19:dd:dd0:ec00:c25:c25:dd6:d570/1242c19:dd:dd0:ec00:c25:c25:dd6:d57f
892c19:dd:dd0:ec00:c25:c25:dd6:d580/1242c19:dd:dd0:ec00:c25:c25:dd6:d58f
902c19:dd:dd0:ec00:c25:c25:dd6:d590/1242c19:dd:dd0:ec00:c25:c25:dd6:d59f
912c19:dd:dd0:ec00:c25:c25:dd6:d5a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d5af
922c19:dd:dd0:ec00:c25:c25:dd6:d5b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d5bf
932c19:dd:dd0:ec00:c25:c25:dd6:d5c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d5cf
942c19:dd:dd0:ec00:c25:c25:dd6:d5d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d5df
952c19:dd:dd0:ec00:c25:c25:dd6:d5e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d5ef
962c19:dd:dd0:ec00:c25:c25:dd6:d5f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d5ff
972c19:dd:dd0:ec00:c25:c25:dd6:d600/1242c19:dd:dd0:ec00:c25:c25:dd6:d60f
982c19:dd:dd0:ec00:c25:c25:dd6:d610/1242c19:dd:dd0:ec00:c25:c25:dd6:d61f
992c19:dd:dd0:ec00:c25:c25:dd6:d620/1242c19:dd:dd0:ec00:c25:c25:dd6:d62f
1002c19:dd:dd0:ec00:c25:c25:dd6:d630/1242c19:dd:dd0:ec00:c25:c25:dd6:d63f
1012c19:dd:dd0:ec00:c25:c25:dd6:d640/1242c19:dd:dd0:ec00:c25:c25:dd6:d64f
1022c19:dd:dd0:ec00:c25:c25:dd6:d650/1242c19:dd:dd0:ec00:c25:c25:dd6:d65f
1032c19:dd:dd0:ec00:c25:c25:dd6:d660/1242c19:dd:dd0:ec00:c25:c25:dd6:d66f
1042c19:dd:dd0:ec00:c25:c25:dd6:d670/1242c19:dd:dd0:ec00:c25:c25:dd6:d67f
1052c19:dd:dd0:ec00:c25:c25:dd6:d680/1242c19:dd:dd0:ec00:c25:c25:dd6:d68f
1062c19:dd:dd0:ec00:c25:c25:dd6:d690/1242c19:dd:dd0:ec00:c25:c25:dd6:d69f
1072c19:dd:dd0:ec00:c25:c25:dd6:d6a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d6af
1082c19:dd:dd0:ec00:c25:c25:dd6:d6b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d6bf
1092c19:dd:dd0:ec00:c25:c25:dd6:d6c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d6cf
1102c19:dd:dd0:ec00:c25:c25:dd6:d6d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d6df
1112c19:dd:dd0:ec00:c25:c25:dd6:d6e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d6ef
1122c19:dd:dd0:ec00:c25:c25:dd6:d6f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d6ff
1132c19:dd:dd0:ec00:c25:c25:dd6:d700/1242c19:dd:dd0:ec00:c25:c25:dd6:d70f
1142c19:dd:dd0:ec00:c25:c25:dd6:d710/1242c19:dd:dd0:ec00:c25:c25:dd6:d71f
1152c19:dd:dd0:ec00:c25:c25:dd6:d720/1242c19:dd:dd0:ec00:c25:c25:dd6:d72f
1162c19:dd:dd0:ec00:c25:c25:dd6:d730/1242c19:dd:dd0:ec00:c25:c25:dd6:d73f
1172c19:dd:dd0:ec00:c25:c25:dd6:d740/1242c19:dd:dd0:ec00:c25:c25:dd6:d74f
1182c19:dd:dd0:ec00:c25:c25:dd6:d750/1242c19:dd:dd0:ec00:c25:c25:dd6:d75f
1192c19:dd:dd0:ec00:c25:c25:dd6:d760/1242c19:dd:dd0:ec00:c25:c25:dd6:d76f
1202c19:dd:dd0:ec00:c25:c25:dd6:d770/1242c19:dd:dd0:ec00:c25:c25:dd6:d77f
1212c19:dd:dd0:ec00:c25:c25:dd6:d780/1242c19:dd:dd0:ec00:c25:c25:dd6:d78f
1222c19:dd:dd0:ec00:c25:c25:dd6:d790/1242c19:dd:dd0:ec00:c25:c25:dd6:d79f
1232c19:dd:dd0:ec00:c25:c25:dd6:d7a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d7af
1242c19:dd:dd0:ec00:c25:c25:dd6:d7b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d7bf
1252c19:dd:dd0:ec00:c25:c25:dd6:d7c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d7cf
1262c19:dd:dd0:ec00:c25:c25:dd6:d7d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d7df
1272c19:dd:dd0:ec00:c25:c25:dd6:d7e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d7ef
1282c19:dd:dd0:ec00:c25:c25:dd6:d7f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d7ff
1292c19:dd:dd0:ec00:c25:c25:dd6:d800/1242c19:dd:dd0:ec00:c25:c25:dd6:d80f
1302c19:dd:dd0:ec00:c25:c25:dd6:d810/1242c19:dd:dd0:ec00:c25:c25:dd6:d81f
1312c19:dd:dd0:ec00:c25:c25:dd6:d820/1242c19:dd:dd0:ec00:c25:c25:dd6:d82f
1322c19:dd:dd0:ec00:c25:c25:dd6:d830/1242c19:dd:dd0:ec00:c25:c25:dd6:d83f
1332c19:dd:dd0:ec00:c25:c25:dd6:d840/1242c19:dd:dd0:ec00:c25:c25:dd6:d84f
1342c19:dd:dd0:ec00:c25:c25:dd6:d850/1242c19:dd:dd0:ec00:c25:c25:dd6:d85f
1352c19:dd:dd0:ec00:c25:c25:dd6:d860/1242c19:dd:dd0:ec00:c25:c25:dd6:d86f
1362c19:dd:dd0:ec00:c25:c25:dd6:d870/1242c19:dd:dd0:ec00:c25:c25:dd6:d87f
1372c19:dd:dd0:ec00:c25:c25:dd6:d880/1242c19:dd:dd0:ec00:c25:c25:dd6:d88f
1382c19:dd:dd0:ec00:c25:c25:dd6:d890/1242c19:dd:dd0:ec00:c25:c25:dd6:d89f
1392c19:dd:dd0:ec00:c25:c25:dd6:d8a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d8af
1402c19:dd:dd0:ec00:c25:c25:dd6:d8b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d8bf
1412c19:dd:dd0:ec00:c25:c25:dd6:d8c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d8cf
1422c19:dd:dd0:ec00:c25:c25:dd6:d8d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d8df
1432c19:dd:dd0:ec00:c25:c25:dd6:d8e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d8ef
1442c19:dd:dd0:ec00:c25:c25:dd6:d8f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d8ff
1452c19:dd:dd0:ec00:c25:c25:dd6:d900/1242c19:dd:dd0:ec00:c25:c25:dd6:d90f
1462c19:dd:dd0:ec00:c25:c25:dd6:d910/1242c19:dd:dd0:ec00:c25:c25:dd6:d91f
1472c19:dd:dd0:ec00:c25:c25:dd6:d920/1242c19:dd:dd0:ec00:c25:c25:dd6:d92f
1482c19:dd:dd0:ec00:c25:c25:dd6:d930/1242c19:dd:dd0:ec00:c25:c25:dd6:d93f
1492c19:dd:dd0:ec00:c25:c25:dd6:d940/1242c19:dd:dd0:ec00:c25:c25:dd6:d94f
1502c19:dd:dd0:ec00:c25:c25:dd6:d950/1242c19:dd:dd0:ec00:c25:c25:dd6:d95f
1512c19:dd:dd0:ec00:c25:c25:dd6:d960/1242c19:dd:dd0:ec00:c25:c25:dd6:d96f
1522c19:dd:dd0:ec00:c25:c25:dd6:d970/1242c19:dd:dd0:ec00:c25:c25:dd6:d97f
1532c19:dd:dd0:ec00:c25:c25:dd6:d980/1242c19:dd:dd0:ec00:c25:c25:dd6:d98f
1542c19:dd:dd0:ec00:c25:c25:dd6:d990/1242c19:dd:dd0:ec00:c25:c25:dd6:d99f
1552c19:dd:dd0:ec00:c25:c25:dd6:d9a0/1242c19:dd:dd0:ec00:c25:c25:dd6:d9af
1562c19:dd:dd0:ec00:c25:c25:dd6:d9b0/1242c19:dd:dd0:ec00:c25:c25:dd6:d9bf
1572c19:dd:dd0:ec00:c25:c25:dd6:d9c0/1242c19:dd:dd0:ec00:c25:c25:dd6:d9cf
1582c19:dd:dd0:ec00:c25:c25:dd6:d9d0/1242c19:dd:dd0:ec00:c25:c25:dd6:d9df
1592c19:dd:dd0:ec00:c25:c25:dd6:d9e0/1242c19:dd:dd0:ec00:c25:c25:dd6:d9ef
1602c19:dd:dd0:ec00:c25:c25:dd6:d9f0/1242c19:dd:dd0:ec00:c25:c25:dd6:d9ff
1612c19:dd:dd0:ec00:c25:c25:dd6:da00/1242c19:dd:dd0:ec00:c25:c25:dd6:da0f
1622c19:dd:dd0:ec00:c25:c25:dd6:da10/1242c19:dd:dd0:ec00:c25:c25:dd6:da1f
1632c19:dd:dd0:ec00:c25:c25:dd6:da20/1242c19:dd:dd0:ec00:c25:c25:dd6:da2f
1642c19:dd:dd0:ec00:c25:c25:dd6:da30/1242c19:dd:dd0:ec00:c25:c25:dd6:da3f
1652c19:dd:dd0:ec00:c25:c25:dd6:da40/1242c19:dd:dd0:ec00:c25:c25:dd6:da4f
1662c19:dd:dd0:ec00:c25:c25:dd6:da50/1242c19:dd:dd0:ec00:c25:c25:dd6:da5f
1672c19:dd:dd0:ec00:c25:c25:dd6:da60/1242c19:dd:dd0:ec00:c25:c25:dd6:da6f
1682c19:dd:dd0:ec00:c25:c25:dd6:da70/1242c19:dd:dd0:ec00:c25:c25:dd6:da7f
1692c19:dd:dd0:ec00:c25:c25:dd6:da80/1242c19:dd:dd0:ec00:c25:c25:dd6:da8f
1702c19:dd:dd0:ec00:c25:c25:dd6:da90/1242c19:dd:dd0:ec00:c25:c25:dd6:da9f
1712c19:dd:dd0:ec00:c25:c25:dd6:daa0/1242c19:dd:dd0:ec00:c25:c25:dd6:daaf
1722c19:dd:dd0:ec00:c25:c25:dd6:dab0/1242c19:dd:dd0:ec00:c25:c25:dd6:dabf
1732c19:dd:dd0:ec00:c25:c25:dd6:dac0/1242c19:dd:dd0:ec00:c25:c25:dd6:dacf
1742c19:dd:dd0:ec00:c25:c25:dd6:dad0/1242c19:dd:dd0:ec00:c25:c25:dd6:dadf
1752c19:dd:dd0:ec00:c25:c25:dd6:dae0/1242c19:dd:dd0:ec00:c25:c25:dd6:daef
1762c19:dd:dd0:ec00:c25:c25:dd6:daf0/1242c19:dd:dd0:ec00:c25:c25:dd6:daff
1772c19:dd:dd0:ec00:c25:c25:dd6:db00/1242c19:dd:dd0:ec00:c25:c25:dd6:db0f
1782c19:dd:dd0:ec00:c25:c25:dd6:db10/1242c19:dd:dd0:ec00:c25:c25:dd6:db1f
1792c19:dd:dd0:ec00:c25:c25:dd6:db20/1242c19:dd:dd0:ec00:c25:c25:dd6:db2f
1802c19:dd:dd0:ec00:c25:c25:dd6:db30/1242c19:dd:dd0:ec00:c25:c25:dd6:db3f
1812c19:dd:dd0:ec00:c25:c25:dd6:db40/1242c19:dd:dd0:ec00:c25:c25:dd6:db4f
1822c19:dd:dd0:ec00:c25:c25:dd6:db50/1242c19:dd:dd0:ec00:c25:c25:dd6:db5f
1832c19:dd:dd0:ec00:c25:c25:dd6:db60/1242c19:dd:dd0:ec00:c25:c25:dd6:db6f
1842c19:dd:dd0:ec00:c25:c25:dd6:db70/1242c19:dd:dd0:ec00:c25:c25:dd6:db7f
1852c19:dd:dd0:ec00:c25:c25:dd6:db80/1242c19:dd:dd0:ec00:c25:c25:dd6:db8f
1862c19:dd:dd0:ec00:c25:c25:dd6:db90/1242c19:dd:dd0:ec00:c25:c25:dd6:db9f
1872c19:dd:dd0:ec00:c25:c25:dd6:dba0/1242c19:dd:dd0:ec00:c25:c25:dd6:dbaf
1882c19:dd:dd0:ec00:c25:c25:dd6:dbb0/1242c19:dd:dd0:ec00:c25:c25:dd6:dbbf
1892c19:dd:dd0:ec00:c25:c25:dd6:dbc0/1242c19:dd:dd0:ec00:c25:c25:dd6:dbcf
1902c19:dd:dd0:ec00:c25:c25:dd6:dbd0/1242c19:dd:dd0:ec00:c25:c25:dd6:dbdf
1912c19:dd:dd0:ec00:c25:c25:dd6:dbe0/1242c19:dd:dd0:ec00:c25:c25:dd6:dbef
1922c19:dd:dd0:ec00:c25:c25:dd6:dbf0/1242c19:dd:dd0:ec00:c25:c25:dd6:dbff
1932c19:dd:dd0:ec00:c25:c25:dd6:dc00/1242c19:dd:dd0:ec00:c25:c25:dd6:dc0f
1942c19:dd:dd0:ec00:c25:c25:dd6:dc10/1242c19:dd:dd0:ec00:c25:c25:dd6:dc1f
1952c19:dd:dd0:ec00:c25:c25:dd6:dc20/1242c19:dd:dd0:ec00:c25:c25:dd6:dc2f
1962c19:dd:dd0:ec00:c25:c25:dd6:dc30/1242c19:dd:dd0:ec00:c25:c25:dd6:dc3f
1972c19:dd:dd0:ec00:c25:c25:dd6:dc40/1242c19:dd:dd0:ec00:c25:c25:dd6:dc4f
1982c19:dd:dd0:ec00:c25:c25:dd6:dc50/1242c19:dd:dd0:ec00:c25:c25:dd6:dc5f
1992c19:dd:dd0:ec00:c25:c25:dd6:dc60/1242c19:dd:dd0:ec00:c25:c25:dd6:dc6f
2002c19:dd:dd0:ec00:c25:c25:dd6:dc70/1242c19:dd:dd0:ec00:c25:c25:dd6:dc7f
2012c19:dd:dd0:ec00:c25:c25:dd6:dc80/1242c19:dd:dd0:ec00:c25:c25:dd6:dc8f
2022c19:dd:dd0:ec00:c25:c25:dd6:dc90/1242c19:dd:dd0:ec00:c25:c25:dd6:dc9f
2032c19:dd:dd0:ec00:c25:c25:dd6:dca0/1242c19:dd:dd0:ec00:c25:c25:dd6:dcaf
2042c19:dd:dd0:ec00:c25:c25:dd6:dcb0/1242c19:dd:dd0:ec00:c25:c25:dd6:dcbf
2052c19:dd:dd0:ec00:c25:c25:dd6:dcc0/1242c19:dd:dd0:ec00:c25:c25:dd6:dccf
2062c19:dd:dd0:ec00:c25:c25:dd6:dcd0/1242c19:dd:dd0:ec00:c25:c25:dd6:dcdf
2072c19:dd:dd0:ec00:c25:c25:dd6:dce0/1242c19:dd:dd0:ec00:c25:c25:dd6:dcef
2082c19:dd:dd0:ec00:c25:c25:dd6:dcf0/1242c19:dd:dd0:ec00:c25:c25:dd6:dcff
2092c19:dd:dd0:ec00:c25:c25:dd6:dd00/1242c19:dd:dd0:ec00:c25:c25:dd6:dd0f
2102c19:dd:dd0:ec00:c25:c25:dd6:dd10/1242c19:dd:dd0:ec00:c25:c25:dd6:dd1f
2112c19:dd:dd0:ec00:c25:c25:dd6:dd20/1242c19:dd:dd0:ec00:c25:c25:dd6:dd2f
2122c19:dd:dd0:ec00:c25:c25:dd6:dd30/1242c19:dd:dd0:ec00:c25:c25:dd6:dd3f
2132c19:dd:dd0:ec00:c25:c25:dd6:dd40/1242c19:dd:dd0:ec00:c25:c25:dd6:dd4f
2142c19:dd:dd0:ec00:c25:c25:dd6:dd50/1242c19:dd:dd0:ec00:c25:c25:dd6:dd5f
2152c19:dd:dd0:ec00:c25:c25:dd6:dd60/1242c19:dd:dd0:ec00:c25:c25:dd6:dd6f
2162c19:dd:dd0:ec00:c25:c25:dd6:dd70/1242c19:dd:dd0:ec00:c25:c25:dd6:dd7f
2172c19:dd:dd0:ec00:c25:c25:dd6:dd80/1242c19:dd:dd0:ec00:c25:c25:dd6:dd8f
2182c19:dd:dd0:ec00:c25:c25:dd6:dd90/1242c19:dd:dd0:ec00:c25:c25:dd6:dd9f
2192c19:dd:dd0:ec00:c25:c25:dd6:dda0/1242c19:dd:dd0:ec00:c25:c25:dd6:ddaf
2202c19:dd:dd0:ec00:c25:c25:dd6:ddb0/1242c19:dd:dd0:ec00:c25:c25:dd6:ddbf
2212c19:dd:dd0:ec00:c25:c25:dd6:ddc0/1242c19:dd:dd0:ec00:c25:c25:dd6:ddcf
2222c19:dd:dd0:ec00:c25:c25:dd6:ddd0/1242c19:dd:dd0:ec00:c25:c25:dd6:dddf
2232c19:dd:dd0:ec00:c25:c25:dd6:dde0/1242c19:dd:dd0:ec00:c25:c25:dd6:ddef
2242c19:dd:dd0:ec00:c25:c25:dd6:ddf0/1242c19:dd:dd0:ec00:c25:c25:dd6:ddff
2252c19:dd:dd0:ec00:c25:c25:dd6:de00/1242c19:dd:dd0:ec00:c25:c25:dd6:de0f
2262c19:dd:dd0:ec00:c25:c25:dd6:de10/1242c19:dd:dd0:ec00:c25:c25:dd6:de1f
2272c19:dd:dd0:ec00:c25:c25:dd6:de20/1242c19:dd:dd0:ec00:c25:c25:dd6:de2f
2282c19:dd:dd0:ec00:c25:c25:dd6:de30/1242c19:dd:dd0:ec00:c25:c25:dd6:de3f
2292c19:dd:dd0:ec00:c25:c25:dd6:de40/1242c19:dd:dd0:ec00:c25:c25:dd6:de4f
2302c19:dd:dd0:ec00:c25:c25:dd6:de50/1242c19:dd:dd0:ec00:c25:c25:dd6:de5f
2312c19:dd:dd0:ec00:c25:c25:dd6:de60/1242c19:dd:dd0:ec00:c25:c25:dd6:de6f
2322c19:dd:dd0:ec00:c25:c25:dd6:de70/1242c19:dd:dd0:ec00:c25:c25:dd6:de7f
2332c19:dd:dd0:ec00:c25:c25:dd6:de80/1242c19:dd:dd0:ec00:c25:c25:dd6:de8f
2342c19:dd:dd0:ec00:c25:c25:dd6:de90/1242c19:dd:dd0:ec00:c25:c25:dd6:de9f
2352c19:dd:dd0:ec00:c25:c25:dd6:dea0/1242c19:dd:dd0:ec00:c25:c25:dd6:deaf
2362c19:dd:dd0:ec00:c25:c25:dd6:deb0/1242c19:dd:dd0:ec00:c25:c25:dd6:debf
2372c19:dd:dd0:ec00:c25:c25:dd6:dec0/1242c19:dd:dd0:ec00:c25:c25:dd6:decf
2382c19:dd:dd0:ec00:c25:c25:dd6:ded0/1242c19:dd:dd0:ec00:c25:c25:dd6:dedf
2392c19:dd:dd0:ec00:c25:c25:dd6:dee0/1242c19:dd:dd0:ec00:c25:c25:dd6:deef
2402c19:dd:dd0:ec00:c25:c25:dd6:def0/1242c19:dd:dd0:ec00:c25:c25:dd6:deff
2412c19:dd:dd0:ec00:c25:c25:dd6:df00/1242c19:dd:dd0:ec00:c25:c25:dd6:df0f
2422c19:dd:dd0:ec00:c25:c25:dd6:df10/1242c19:dd:dd0:ec00:c25:c25:dd6:df1f
2432c19:dd:dd0:ec00:c25:c25:dd6:df20/1242c19:dd:dd0:ec00:c25:c25:dd6:df2f
2442c19:dd:dd0:ec00:c25:c25:dd6:df30/1242c19:dd:dd0:ec00:c25:c25:dd6:df3f
2452c19:dd:dd0:ec00:c25:c25:dd6:df40/1242c19:dd:dd0:ec00:c25:c25:dd6:df4f
2462c19:dd:dd0:ec00:c25:c25:dd6:df50/1242c19:dd:dd0:ec00:c25:c25:dd6:df5f
2472c19:dd:dd0:ec00:c25:c25:dd6:df60/1242c19:dd:dd0:ec00:c25:c25:dd6:df6f
2482c19:dd:dd0:ec00:c25:c25:dd6:df70/1242c19:dd:dd0:ec00:c25:c25:dd6:df7f
2492c19:dd:dd0:ec00:c25:c25:dd6:df80/1242c19:dd:dd0:ec00:c25:c25:dd6:df8f
2502c19:dd:dd0:ec00:c25:c25:dd6:df90/1242c19:dd:dd0:ec00:c25:c25:dd6:df9f
2512c19:dd:dd0:ec00:c25:c25:dd6:dfa0/1242c19:dd:dd0:ec00:c25:c25:dd6:dfaf
2522c19:dd:dd0:ec00:c25:c25:dd6:dfb0/1242c19:dd:dd0:ec00:c25:c25:dd6:dfbf
2532c19:dd:dd0:ec00:c25:c25:dd6:dfc0/1242c19:dd:dd0:ec00:c25:c25:dd6:dfcf
2542c19:dd:dd0:ec00:c25:c25:dd6:dfd0/1242c19:dd:dd0:ec00:c25:c25:dd6:dfdf
2552c19:dd:dd0:ec00:c25:c25:dd6:dfe0/1242c19:dd:dd0:ec00:c25:c25:dd6:dfef
2562c19:dd:dd0:ec00:c25:c25:dd6:dff0/1242c19:dd:dd0:ec00:c25:c25:dd6:dfff

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.