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:f007:e000/116
First address
2c19:dd:d9:dd:c25:c25:f007:e000
Last address
2c19:dd:d9:dd:c25:c25:f007:efff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:f007:e000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
e.7.0.0.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/124
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2c19:dd:d9:dd:c25:c25:f007:e000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:f007:e000/1242c19:dd:d9:dd:c25:c25:f007:e00f
22c19:dd:d9:dd:c25:c25:f007:e010/1242c19:dd:d9:dd:c25:c25:f007:e01f
32c19:dd:d9:dd:c25:c25:f007:e020/1242c19:dd:d9:dd:c25:c25:f007:e02f
42c19:dd:d9:dd:c25:c25:f007:e030/1242c19:dd:d9:dd:c25:c25:f007:e03f
52c19:dd:d9:dd:c25:c25:f007:e040/1242c19:dd:d9:dd:c25:c25:f007:e04f
62c19:dd:d9:dd:c25:c25:f007:e050/1242c19:dd:d9:dd:c25:c25:f007:e05f
72c19:dd:d9:dd:c25:c25:f007:e060/1242c19:dd:d9:dd:c25:c25:f007:e06f
82c19:dd:d9:dd:c25:c25:f007:e070/1242c19:dd:d9:dd:c25:c25:f007:e07f
92c19:dd:d9:dd:c25:c25:f007:e080/1242c19:dd:d9:dd:c25:c25:f007:e08f
102c19:dd:d9:dd:c25:c25:f007:e090/1242c19:dd:d9:dd:c25:c25:f007:e09f
112c19:dd:d9:dd:c25:c25:f007:e0a0/1242c19:dd:d9:dd:c25:c25:f007:e0af
122c19:dd:d9:dd:c25:c25:f007:e0b0/1242c19:dd:d9:dd:c25:c25:f007:e0bf
132c19:dd:d9:dd:c25:c25:f007:e0c0/1242c19:dd:d9:dd:c25:c25:f007:e0cf
142c19:dd:d9:dd:c25:c25:f007:e0d0/1242c19:dd:d9:dd:c25:c25:f007:e0df
152c19:dd:d9:dd:c25:c25:f007:e0e0/1242c19:dd:d9:dd:c25:c25:f007:e0ef
162c19:dd:d9:dd:c25:c25:f007:e0f0/1242c19:dd:d9:dd:c25:c25:f007:e0ff
172c19:dd:d9:dd:c25:c25:f007:e100/1242c19:dd:d9:dd:c25:c25:f007:e10f
182c19:dd:d9:dd:c25:c25:f007:e110/1242c19:dd:d9:dd:c25:c25:f007:e11f
192c19:dd:d9:dd:c25:c25:f007:e120/1242c19:dd:d9:dd:c25:c25:f007:e12f
202c19:dd:d9:dd:c25:c25:f007:e130/1242c19:dd:d9:dd:c25:c25:f007:e13f
212c19:dd:d9:dd:c25:c25:f007:e140/1242c19:dd:d9:dd:c25:c25:f007:e14f
222c19:dd:d9:dd:c25:c25:f007:e150/1242c19:dd:d9:dd:c25:c25:f007:e15f
232c19:dd:d9:dd:c25:c25:f007:e160/1242c19:dd:d9:dd:c25:c25:f007:e16f
242c19:dd:d9:dd:c25:c25:f007:e170/1242c19:dd:d9:dd:c25:c25:f007:e17f
252c19:dd:d9:dd:c25:c25:f007:e180/1242c19:dd:d9:dd:c25:c25:f007:e18f
262c19:dd:d9:dd:c25:c25:f007:e190/1242c19:dd:d9:dd:c25:c25:f007:e19f
272c19:dd:d9:dd:c25:c25:f007:e1a0/1242c19:dd:d9:dd:c25:c25:f007:e1af
282c19:dd:d9:dd:c25:c25:f007:e1b0/1242c19:dd:d9:dd:c25:c25:f007:e1bf
292c19:dd:d9:dd:c25:c25:f007:e1c0/1242c19:dd:d9:dd:c25:c25:f007:e1cf
302c19:dd:d9:dd:c25:c25:f007:e1d0/1242c19:dd:d9:dd:c25:c25:f007:e1df
312c19:dd:d9:dd:c25:c25:f007:e1e0/1242c19:dd:d9:dd:c25:c25:f007:e1ef
322c19:dd:d9:dd:c25:c25:f007:e1f0/1242c19:dd:d9:dd:c25:c25:f007:e1ff
332c19:dd:d9:dd:c25:c25:f007:e200/1242c19:dd:d9:dd:c25:c25:f007:e20f
342c19:dd:d9:dd:c25:c25:f007:e210/1242c19:dd:d9:dd:c25:c25:f007:e21f
352c19:dd:d9:dd:c25:c25:f007:e220/1242c19:dd:d9:dd:c25:c25:f007:e22f
362c19:dd:d9:dd:c25:c25:f007:e230/1242c19:dd:d9:dd:c25:c25:f007:e23f
372c19:dd:d9:dd:c25:c25:f007:e240/1242c19:dd:d9:dd:c25:c25:f007:e24f
382c19:dd:d9:dd:c25:c25:f007:e250/1242c19:dd:d9:dd:c25:c25:f007:e25f
392c19:dd:d9:dd:c25:c25:f007:e260/1242c19:dd:d9:dd:c25:c25:f007:e26f
402c19:dd:d9:dd:c25:c25:f007:e270/1242c19:dd:d9:dd:c25:c25:f007:e27f
412c19:dd:d9:dd:c25:c25:f007:e280/1242c19:dd:d9:dd:c25:c25:f007:e28f
422c19:dd:d9:dd:c25:c25:f007:e290/1242c19:dd:d9:dd:c25:c25:f007:e29f
432c19:dd:d9:dd:c25:c25:f007:e2a0/1242c19:dd:d9:dd:c25:c25:f007:e2af
442c19:dd:d9:dd:c25:c25:f007:e2b0/1242c19:dd:d9:dd:c25:c25:f007:e2bf
452c19:dd:d9:dd:c25:c25:f007:e2c0/1242c19:dd:d9:dd:c25:c25:f007:e2cf
462c19:dd:d9:dd:c25:c25:f007:e2d0/1242c19:dd:d9:dd:c25:c25:f007:e2df
472c19:dd:d9:dd:c25:c25:f007:e2e0/1242c19:dd:d9:dd:c25:c25:f007:e2ef
482c19:dd:d9:dd:c25:c25:f007:e2f0/1242c19:dd:d9:dd:c25:c25:f007:e2ff
492c19:dd:d9:dd:c25:c25:f007:e300/1242c19:dd:d9:dd:c25:c25:f007:e30f
502c19:dd:d9:dd:c25:c25:f007:e310/1242c19:dd:d9:dd:c25:c25:f007:e31f
512c19:dd:d9:dd:c25:c25:f007:e320/1242c19:dd:d9:dd:c25:c25:f007:e32f
522c19:dd:d9:dd:c25:c25:f007:e330/1242c19:dd:d9:dd:c25:c25:f007:e33f
532c19:dd:d9:dd:c25:c25:f007:e340/1242c19:dd:d9:dd:c25:c25:f007:e34f
542c19:dd:d9:dd:c25:c25:f007:e350/1242c19:dd:d9:dd:c25:c25:f007:e35f
552c19:dd:d9:dd:c25:c25:f007:e360/1242c19:dd:d9:dd:c25:c25:f007:e36f
562c19:dd:d9:dd:c25:c25:f007:e370/1242c19:dd:d9:dd:c25:c25:f007:e37f
572c19:dd:d9:dd:c25:c25:f007:e380/1242c19:dd:d9:dd:c25:c25:f007:e38f
582c19:dd:d9:dd:c25:c25:f007:e390/1242c19:dd:d9:dd:c25:c25:f007:e39f
592c19:dd:d9:dd:c25:c25:f007:e3a0/1242c19:dd:d9:dd:c25:c25:f007:e3af
602c19:dd:d9:dd:c25:c25:f007:e3b0/1242c19:dd:d9:dd:c25:c25:f007:e3bf
612c19:dd:d9:dd:c25:c25:f007:e3c0/1242c19:dd:d9:dd:c25:c25:f007:e3cf
622c19:dd:d9:dd:c25:c25:f007:e3d0/1242c19:dd:d9:dd:c25:c25:f007:e3df
632c19:dd:d9:dd:c25:c25:f007:e3e0/1242c19:dd:d9:dd:c25:c25:f007:e3ef
642c19:dd:d9:dd:c25:c25:f007:e3f0/1242c19:dd:d9:dd:c25:c25:f007:e3ff
652c19:dd:d9:dd:c25:c25:f007:e400/1242c19:dd:d9:dd:c25:c25:f007:e40f
662c19:dd:d9:dd:c25:c25:f007:e410/1242c19:dd:d9:dd:c25:c25:f007:e41f
672c19:dd:d9:dd:c25:c25:f007:e420/1242c19:dd:d9:dd:c25:c25:f007:e42f
682c19:dd:d9:dd:c25:c25:f007:e430/1242c19:dd:d9:dd:c25:c25:f007:e43f
692c19:dd:d9:dd:c25:c25:f007:e440/1242c19:dd:d9:dd:c25:c25:f007:e44f
702c19:dd:d9:dd:c25:c25:f007:e450/1242c19:dd:d9:dd:c25:c25:f007:e45f
712c19:dd:d9:dd:c25:c25:f007:e460/1242c19:dd:d9:dd:c25:c25:f007:e46f
722c19:dd:d9:dd:c25:c25:f007:e470/1242c19:dd:d9:dd:c25:c25:f007:e47f
732c19:dd:d9:dd:c25:c25:f007:e480/1242c19:dd:d9:dd:c25:c25:f007:e48f
742c19:dd:d9:dd:c25:c25:f007:e490/1242c19:dd:d9:dd:c25:c25:f007:e49f
752c19:dd:d9:dd:c25:c25:f007:e4a0/1242c19:dd:d9:dd:c25:c25:f007:e4af
762c19:dd:d9:dd:c25:c25:f007:e4b0/1242c19:dd:d9:dd:c25:c25:f007:e4bf
772c19:dd:d9:dd:c25:c25:f007:e4c0/1242c19:dd:d9:dd:c25:c25:f007:e4cf
782c19:dd:d9:dd:c25:c25:f007:e4d0/1242c19:dd:d9:dd:c25:c25:f007:e4df
792c19:dd:d9:dd:c25:c25:f007:e4e0/1242c19:dd:d9:dd:c25:c25:f007:e4ef
802c19:dd:d9:dd:c25:c25:f007:e4f0/1242c19:dd:d9:dd:c25:c25:f007:e4ff
812c19:dd:d9:dd:c25:c25:f007:e500/1242c19:dd:d9:dd:c25:c25:f007:e50f
822c19:dd:d9:dd:c25:c25:f007:e510/1242c19:dd:d9:dd:c25:c25:f007:e51f
832c19:dd:d9:dd:c25:c25:f007:e520/1242c19:dd:d9:dd:c25:c25:f007:e52f
842c19:dd:d9:dd:c25:c25:f007:e530/1242c19:dd:d9:dd:c25:c25:f007:e53f
852c19:dd:d9:dd:c25:c25:f007:e540/1242c19:dd:d9:dd:c25:c25:f007:e54f
862c19:dd:d9:dd:c25:c25:f007:e550/1242c19:dd:d9:dd:c25:c25:f007:e55f
872c19:dd:d9:dd:c25:c25:f007:e560/1242c19:dd:d9:dd:c25:c25:f007:e56f
882c19:dd:d9:dd:c25:c25:f007:e570/1242c19:dd:d9:dd:c25:c25:f007:e57f
892c19:dd:d9:dd:c25:c25:f007:e580/1242c19:dd:d9:dd:c25:c25:f007:e58f
902c19:dd:d9:dd:c25:c25:f007:e590/1242c19:dd:d9:dd:c25:c25:f007:e59f
912c19:dd:d9:dd:c25:c25:f007:e5a0/1242c19:dd:d9:dd:c25:c25:f007:e5af
922c19:dd:d9:dd:c25:c25:f007:e5b0/1242c19:dd:d9:dd:c25:c25:f007:e5bf
932c19:dd:d9:dd:c25:c25:f007:e5c0/1242c19:dd:d9:dd:c25:c25:f007:e5cf
942c19:dd:d9:dd:c25:c25:f007:e5d0/1242c19:dd:d9:dd:c25:c25:f007:e5df
952c19:dd:d9:dd:c25:c25:f007:e5e0/1242c19:dd:d9:dd:c25:c25:f007:e5ef
962c19:dd:d9:dd:c25:c25:f007:e5f0/1242c19:dd:d9:dd:c25:c25:f007:e5ff
972c19:dd:d9:dd:c25:c25:f007:e600/1242c19:dd:d9:dd:c25:c25:f007:e60f
982c19:dd:d9:dd:c25:c25:f007:e610/1242c19:dd:d9:dd:c25:c25:f007:e61f
992c19:dd:d9:dd:c25:c25:f007:e620/1242c19:dd:d9:dd:c25:c25:f007:e62f
1002c19:dd:d9:dd:c25:c25:f007:e630/1242c19:dd:d9:dd:c25:c25:f007:e63f
1012c19:dd:d9:dd:c25:c25:f007:e640/1242c19:dd:d9:dd:c25:c25:f007:e64f
1022c19:dd:d9:dd:c25:c25:f007:e650/1242c19:dd:d9:dd:c25:c25:f007:e65f
1032c19:dd:d9:dd:c25:c25:f007:e660/1242c19:dd:d9:dd:c25:c25:f007:e66f
1042c19:dd:d9:dd:c25:c25:f007:e670/1242c19:dd:d9:dd:c25:c25:f007:e67f
1052c19:dd:d9:dd:c25:c25:f007:e680/1242c19:dd:d9:dd:c25:c25:f007:e68f
1062c19:dd:d9:dd:c25:c25:f007:e690/1242c19:dd:d9:dd:c25:c25:f007:e69f
1072c19:dd:d9:dd:c25:c25:f007:e6a0/1242c19:dd:d9:dd:c25:c25:f007:e6af
1082c19:dd:d9:dd:c25:c25:f007:e6b0/1242c19:dd:d9:dd:c25:c25:f007:e6bf
1092c19:dd:d9:dd:c25:c25:f007:e6c0/1242c19:dd:d9:dd:c25:c25:f007:e6cf
1102c19:dd:d9:dd:c25:c25:f007:e6d0/1242c19:dd:d9:dd:c25:c25:f007:e6df
1112c19:dd:d9:dd:c25:c25:f007:e6e0/1242c19:dd:d9:dd:c25:c25:f007:e6ef
1122c19:dd:d9:dd:c25:c25:f007:e6f0/1242c19:dd:d9:dd:c25:c25:f007:e6ff
1132c19:dd:d9:dd:c25:c25:f007:e700/1242c19:dd:d9:dd:c25:c25:f007:e70f
1142c19:dd:d9:dd:c25:c25:f007:e710/1242c19:dd:d9:dd:c25:c25:f007:e71f
1152c19:dd:d9:dd:c25:c25:f007:e720/1242c19:dd:d9:dd:c25:c25:f007:e72f
1162c19:dd:d9:dd:c25:c25:f007:e730/1242c19:dd:d9:dd:c25:c25:f007:e73f
1172c19:dd:d9:dd:c25:c25:f007:e740/1242c19:dd:d9:dd:c25:c25:f007:e74f
1182c19:dd:d9:dd:c25:c25:f007:e750/1242c19:dd:d9:dd:c25:c25:f007:e75f
1192c19:dd:d9:dd:c25:c25:f007:e760/1242c19:dd:d9:dd:c25:c25:f007:e76f
1202c19:dd:d9:dd:c25:c25:f007:e770/1242c19:dd:d9:dd:c25:c25:f007:e77f
1212c19:dd:d9:dd:c25:c25:f007:e780/1242c19:dd:d9:dd:c25:c25:f007:e78f
1222c19:dd:d9:dd:c25:c25:f007:e790/1242c19:dd:d9:dd:c25:c25:f007:e79f
1232c19:dd:d9:dd:c25:c25:f007:e7a0/1242c19:dd:d9:dd:c25:c25:f007:e7af
1242c19:dd:d9:dd:c25:c25:f007:e7b0/1242c19:dd:d9:dd:c25:c25:f007:e7bf
1252c19:dd:d9:dd:c25:c25:f007:e7c0/1242c19:dd:d9:dd:c25:c25:f007:e7cf
1262c19:dd:d9:dd:c25:c25:f007:e7d0/1242c19:dd:d9:dd:c25:c25:f007:e7df
1272c19:dd:d9:dd:c25:c25:f007:e7e0/1242c19:dd:d9:dd:c25:c25:f007:e7ef
1282c19:dd:d9:dd:c25:c25:f007:e7f0/1242c19:dd:d9:dd:c25:c25:f007:e7ff
1292c19:dd:d9:dd:c25:c25:f007:e800/1242c19:dd:d9:dd:c25:c25:f007:e80f
1302c19:dd:d9:dd:c25:c25:f007:e810/1242c19:dd:d9:dd:c25:c25:f007:e81f
1312c19:dd:d9:dd:c25:c25:f007:e820/1242c19:dd:d9:dd:c25:c25:f007:e82f
1322c19:dd:d9:dd:c25:c25:f007:e830/1242c19:dd:d9:dd:c25:c25:f007:e83f
1332c19:dd:d9:dd:c25:c25:f007:e840/1242c19:dd:d9:dd:c25:c25:f007:e84f
1342c19:dd:d9:dd:c25:c25:f007:e850/1242c19:dd:d9:dd:c25:c25:f007:e85f
1352c19:dd:d9:dd:c25:c25:f007:e860/1242c19:dd:d9:dd:c25:c25:f007:e86f
1362c19:dd:d9:dd:c25:c25:f007:e870/1242c19:dd:d9:dd:c25:c25:f007:e87f
1372c19:dd:d9:dd:c25:c25:f007:e880/1242c19:dd:d9:dd:c25:c25:f007:e88f
1382c19:dd:d9:dd:c25:c25:f007:e890/1242c19:dd:d9:dd:c25:c25:f007:e89f
1392c19:dd:d9:dd:c25:c25:f007:e8a0/1242c19:dd:d9:dd:c25:c25:f007:e8af
1402c19:dd:d9:dd:c25:c25:f007:e8b0/1242c19:dd:d9:dd:c25:c25:f007:e8bf
1412c19:dd:d9:dd:c25:c25:f007:e8c0/1242c19:dd:d9:dd:c25:c25:f007:e8cf
1422c19:dd:d9:dd:c25:c25:f007:e8d0/1242c19:dd:d9:dd:c25:c25:f007:e8df
1432c19:dd:d9:dd:c25:c25:f007:e8e0/1242c19:dd:d9:dd:c25:c25:f007:e8ef
1442c19:dd:d9:dd:c25:c25:f007:e8f0/1242c19:dd:d9:dd:c25:c25:f007:e8ff
1452c19:dd:d9:dd:c25:c25:f007:e900/1242c19:dd:d9:dd:c25:c25:f007:e90f
1462c19:dd:d9:dd:c25:c25:f007:e910/1242c19:dd:d9:dd:c25:c25:f007:e91f
1472c19:dd:d9:dd:c25:c25:f007:e920/1242c19:dd:d9:dd:c25:c25:f007:e92f
1482c19:dd:d9:dd:c25:c25:f007:e930/1242c19:dd:d9:dd:c25:c25:f007:e93f
1492c19:dd:d9:dd:c25:c25:f007:e940/1242c19:dd:d9:dd:c25:c25:f007:e94f
1502c19:dd:d9:dd:c25:c25:f007:e950/1242c19:dd:d9:dd:c25:c25:f007:e95f
1512c19:dd:d9:dd:c25:c25:f007:e960/1242c19:dd:d9:dd:c25:c25:f007:e96f
1522c19:dd:d9:dd:c25:c25:f007:e970/1242c19:dd:d9:dd:c25:c25:f007:e97f
1532c19:dd:d9:dd:c25:c25:f007:e980/1242c19:dd:d9:dd:c25:c25:f007:e98f
1542c19:dd:d9:dd:c25:c25:f007:e990/1242c19:dd:d9:dd:c25:c25:f007:e99f
1552c19:dd:d9:dd:c25:c25:f007:e9a0/1242c19:dd:d9:dd:c25:c25:f007:e9af
1562c19:dd:d9:dd:c25:c25:f007:e9b0/1242c19:dd:d9:dd:c25:c25:f007:e9bf
1572c19:dd:d9:dd:c25:c25:f007:e9c0/1242c19:dd:d9:dd:c25:c25:f007:e9cf
1582c19:dd:d9:dd:c25:c25:f007:e9d0/1242c19:dd:d9:dd:c25:c25:f007:e9df
1592c19:dd:d9:dd:c25:c25:f007:e9e0/1242c19:dd:d9:dd:c25:c25:f007:e9ef
1602c19:dd:d9:dd:c25:c25:f007:e9f0/1242c19:dd:d9:dd:c25:c25:f007:e9ff
1612c19:dd:d9:dd:c25:c25:f007:ea00/1242c19:dd:d9:dd:c25:c25:f007:ea0f
1622c19:dd:d9:dd:c25:c25:f007:ea10/1242c19:dd:d9:dd:c25:c25:f007:ea1f
1632c19:dd:d9:dd:c25:c25:f007:ea20/1242c19:dd:d9:dd:c25:c25:f007:ea2f
1642c19:dd:d9:dd:c25:c25:f007:ea30/1242c19:dd:d9:dd:c25:c25:f007:ea3f
1652c19:dd:d9:dd:c25:c25:f007:ea40/1242c19:dd:d9:dd:c25:c25:f007:ea4f
1662c19:dd:d9:dd:c25:c25:f007:ea50/1242c19:dd:d9:dd:c25:c25:f007:ea5f
1672c19:dd:d9:dd:c25:c25:f007:ea60/1242c19:dd:d9:dd:c25:c25:f007:ea6f
1682c19:dd:d9:dd:c25:c25:f007:ea70/1242c19:dd:d9:dd:c25:c25:f007:ea7f
1692c19:dd:d9:dd:c25:c25:f007:ea80/1242c19:dd:d9:dd:c25:c25:f007:ea8f
1702c19:dd:d9:dd:c25:c25:f007:ea90/1242c19:dd:d9:dd:c25:c25:f007:ea9f
1712c19:dd:d9:dd:c25:c25:f007:eaa0/1242c19:dd:d9:dd:c25:c25:f007:eaaf
1722c19:dd:d9:dd:c25:c25:f007:eab0/1242c19:dd:d9:dd:c25:c25:f007:eabf
1732c19:dd:d9:dd:c25:c25:f007:eac0/1242c19:dd:d9:dd:c25:c25:f007:eacf
1742c19:dd:d9:dd:c25:c25:f007:ead0/1242c19:dd:d9:dd:c25:c25:f007:eadf
1752c19:dd:d9:dd:c25:c25:f007:eae0/1242c19:dd:d9:dd:c25:c25:f007:eaef
1762c19:dd:d9:dd:c25:c25:f007:eaf0/1242c19:dd:d9:dd:c25:c25:f007:eaff
1772c19:dd:d9:dd:c25:c25:f007:eb00/1242c19:dd:d9:dd:c25:c25:f007:eb0f
1782c19:dd:d9:dd:c25:c25:f007:eb10/1242c19:dd:d9:dd:c25:c25:f007:eb1f
1792c19:dd:d9:dd:c25:c25:f007:eb20/1242c19:dd:d9:dd:c25:c25:f007:eb2f
1802c19:dd:d9:dd:c25:c25:f007:eb30/1242c19:dd:d9:dd:c25:c25:f007:eb3f
1812c19:dd:d9:dd:c25:c25:f007:eb40/1242c19:dd:d9:dd:c25:c25:f007:eb4f
1822c19:dd:d9:dd:c25:c25:f007:eb50/1242c19:dd:d9:dd:c25:c25:f007:eb5f
1832c19:dd:d9:dd:c25:c25:f007:eb60/1242c19:dd:d9:dd:c25:c25:f007:eb6f
1842c19:dd:d9:dd:c25:c25:f007:eb70/1242c19:dd:d9:dd:c25:c25:f007:eb7f
1852c19:dd:d9:dd:c25:c25:f007:eb80/1242c19:dd:d9:dd:c25:c25:f007:eb8f
1862c19:dd:d9:dd:c25:c25:f007:eb90/1242c19:dd:d9:dd:c25:c25:f007:eb9f
1872c19:dd:d9:dd:c25:c25:f007:eba0/1242c19:dd:d9:dd:c25:c25:f007:ebaf
1882c19:dd:d9:dd:c25:c25:f007:ebb0/1242c19:dd:d9:dd:c25:c25:f007:ebbf
1892c19:dd:d9:dd:c25:c25:f007:ebc0/1242c19:dd:d9:dd:c25:c25:f007:ebcf
1902c19:dd:d9:dd:c25:c25:f007:ebd0/1242c19:dd:d9:dd:c25:c25:f007:ebdf
1912c19:dd:d9:dd:c25:c25:f007:ebe0/1242c19:dd:d9:dd:c25:c25:f007:ebef
1922c19:dd:d9:dd:c25:c25:f007:ebf0/1242c19:dd:d9:dd:c25:c25:f007:ebff
1932c19:dd:d9:dd:c25:c25:f007:ec00/1242c19:dd:d9:dd:c25:c25:f007:ec0f
1942c19:dd:d9:dd:c25:c25:f007:ec10/1242c19:dd:d9:dd:c25:c25:f007:ec1f
1952c19:dd:d9:dd:c25:c25:f007:ec20/1242c19:dd:d9:dd:c25:c25:f007:ec2f
1962c19:dd:d9:dd:c25:c25:f007:ec30/1242c19:dd:d9:dd:c25:c25:f007:ec3f
1972c19:dd:d9:dd:c25:c25:f007:ec40/1242c19:dd:d9:dd:c25:c25:f007:ec4f
1982c19:dd:d9:dd:c25:c25:f007:ec50/1242c19:dd:d9:dd:c25:c25:f007:ec5f
1992c19:dd:d9:dd:c25:c25:f007:ec60/1242c19:dd:d9:dd:c25:c25:f007:ec6f
2002c19:dd:d9:dd:c25:c25:f007:ec70/1242c19:dd:d9:dd:c25:c25:f007:ec7f
2012c19:dd:d9:dd:c25:c25:f007:ec80/1242c19:dd:d9:dd:c25:c25:f007:ec8f
2022c19:dd:d9:dd:c25:c25:f007:ec90/1242c19:dd:d9:dd:c25:c25:f007:ec9f
2032c19:dd:d9:dd:c25:c25:f007:eca0/1242c19:dd:d9:dd:c25:c25:f007:ecaf
2042c19:dd:d9:dd:c25:c25:f007:ecb0/1242c19:dd:d9:dd:c25:c25:f007:ecbf
2052c19:dd:d9:dd:c25:c25:f007:ecc0/1242c19:dd:d9:dd:c25:c25:f007:eccf
2062c19:dd:d9:dd:c25:c25:f007:ecd0/1242c19:dd:d9:dd:c25:c25:f007:ecdf
2072c19:dd:d9:dd:c25:c25:f007:ece0/1242c19:dd:d9:dd:c25:c25:f007:ecef
2082c19:dd:d9:dd:c25:c25:f007:ecf0/1242c19:dd:d9:dd:c25:c25:f007:ecff
2092c19:dd:d9:dd:c25:c25:f007:ed00/1242c19:dd:d9:dd:c25:c25:f007:ed0f
2102c19:dd:d9:dd:c25:c25:f007:ed10/1242c19:dd:d9:dd:c25:c25:f007:ed1f
2112c19:dd:d9:dd:c25:c25:f007:ed20/1242c19:dd:d9:dd:c25:c25:f007:ed2f
2122c19:dd:d9:dd:c25:c25:f007:ed30/1242c19:dd:d9:dd:c25:c25:f007:ed3f
2132c19:dd:d9:dd:c25:c25:f007:ed40/1242c19:dd:d9:dd:c25:c25:f007:ed4f
2142c19:dd:d9:dd:c25:c25:f007:ed50/1242c19:dd:d9:dd:c25:c25:f007:ed5f
2152c19:dd:d9:dd:c25:c25:f007:ed60/1242c19:dd:d9:dd:c25:c25:f007:ed6f
2162c19:dd:d9:dd:c25:c25:f007:ed70/1242c19:dd:d9:dd:c25:c25:f007:ed7f
2172c19:dd:d9:dd:c25:c25:f007:ed80/1242c19:dd:d9:dd:c25:c25:f007:ed8f
2182c19:dd:d9:dd:c25:c25:f007:ed90/1242c19:dd:d9:dd:c25:c25:f007:ed9f
2192c19:dd:d9:dd:c25:c25:f007:eda0/1242c19:dd:d9:dd:c25:c25:f007:edaf
2202c19:dd:d9:dd:c25:c25:f007:edb0/1242c19:dd:d9:dd:c25:c25:f007:edbf
2212c19:dd:d9:dd:c25:c25:f007:edc0/1242c19:dd:d9:dd:c25:c25:f007:edcf
2222c19:dd:d9:dd:c25:c25:f007:edd0/1242c19:dd:d9:dd:c25:c25:f007:eddf
2232c19:dd:d9:dd:c25:c25:f007:ede0/1242c19:dd:d9:dd:c25:c25:f007:edef
2242c19:dd:d9:dd:c25:c25:f007:edf0/1242c19:dd:d9:dd:c25:c25:f007:edff
2252c19:dd:d9:dd:c25:c25:f007:ee00/1242c19:dd:d9:dd:c25:c25:f007:ee0f
2262c19:dd:d9:dd:c25:c25:f007:ee10/1242c19:dd:d9:dd:c25:c25:f007:ee1f
2272c19:dd:d9:dd:c25:c25:f007:ee20/1242c19:dd:d9:dd:c25:c25:f007:ee2f
2282c19:dd:d9:dd:c25:c25:f007:ee30/1242c19:dd:d9:dd:c25:c25:f007:ee3f
2292c19:dd:d9:dd:c25:c25:f007:ee40/1242c19:dd:d9:dd:c25:c25:f007:ee4f
2302c19:dd:d9:dd:c25:c25:f007:ee50/1242c19:dd:d9:dd:c25:c25:f007:ee5f
2312c19:dd:d9:dd:c25:c25:f007:ee60/1242c19:dd:d9:dd:c25:c25:f007:ee6f
2322c19:dd:d9:dd:c25:c25:f007:ee70/1242c19:dd:d9:dd:c25:c25:f007:ee7f
2332c19:dd:d9:dd:c25:c25:f007:ee80/1242c19:dd:d9:dd:c25:c25:f007:ee8f
2342c19:dd:d9:dd:c25:c25:f007:ee90/1242c19:dd:d9:dd:c25:c25:f007:ee9f
2352c19:dd:d9:dd:c25:c25:f007:eea0/1242c19:dd:d9:dd:c25:c25:f007:eeaf
2362c19:dd:d9:dd:c25:c25:f007:eeb0/1242c19:dd:d9:dd:c25:c25:f007:eebf
2372c19:dd:d9:dd:c25:c25:f007:eec0/1242c19:dd:d9:dd:c25:c25:f007:eecf
2382c19:dd:d9:dd:c25:c25:f007:eed0/1242c19:dd:d9:dd:c25:c25:f007:eedf
2392c19:dd:d9:dd:c25:c25:f007:eee0/1242c19:dd:d9:dd:c25:c25:f007:eeef
2402c19:dd:d9:dd:c25:c25:f007:eef0/1242c19:dd:d9:dd:c25:c25:f007:eeff
2412c19:dd:d9:dd:c25:c25:f007:ef00/1242c19:dd:d9:dd:c25:c25:f007:ef0f
2422c19:dd:d9:dd:c25:c25:f007:ef10/1242c19:dd:d9:dd:c25:c25:f007:ef1f
2432c19:dd:d9:dd:c25:c25:f007:ef20/1242c19:dd:d9:dd:c25:c25:f007:ef2f
2442c19:dd:d9:dd:c25:c25:f007:ef30/1242c19:dd:d9:dd:c25:c25:f007:ef3f
2452c19:dd:d9:dd:c25:c25:f007:ef40/1242c19:dd:d9:dd:c25:c25:f007:ef4f
2462c19:dd:d9:dd:c25:c25:f007:ef50/1242c19:dd:d9:dd:c25:c25:f007:ef5f
2472c19:dd:d9:dd:c25:c25:f007:ef60/1242c19:dd:d9:dd:c25:c25:f007:ef6f
2482c19:dd:d9:dd:c25:c25:f007:ef70/1242c19:dd:d9:dd:c25:c25:f007:ef7f
2492c19:dd:d9:dd:c25:c25:f007:ef80/1242c19:dd:d9:dd:c25:c25:f007:ef8f
2502c19:dd:d9:dd:c25:c25:f007:ef90/1242c19:dd:d9:dd:c25:c25:f007:ef9f
2512c19:dd:d9:dd:c25:c25:f007:efa0/1242c19:dd:d9:dd:c25:c25:f007:efaf
2522c19:dd:d9:dd:c25:c25:f007:efb0/1242c19:dd:d9:dd:c25:c25:f007:efbf
2532c19:dd:d9:dd:c25:c25:f007:efc0/1242c19:dd:d9:dd:c25:c25:f007:efcf
2542c19:dd:d9:dd:c25:c25:f007:efd0/1242c19:dd:d9:dd:c25:c25:f007:efdf
2552c19:dd:d9:dd:c25:c25:f007:efe0/1242c19:dd:d9:dd:c25:c25:f007:efef
2562c19:dd:d9:dd:c25:c25:f007:eff0/1242c19:dd:d9:dd:c25:c25:f007:efff

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.