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/115
Addresses8,192
/64 networksPart of one
Network
2c19:dd:c25:c25f:dd4e:dd:dd:a000/115
First address
2c19:dd:c25:c25f:dd4e:dd:dd:a000
Last address
2c19:dd:c25:c25f:dd4e:dd:dd:bfff
Addresses
8,192
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:0c25:c25f:dd4e:00dd:00dd:a000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
a.d.d.0.0.d.d.0.0.e.4.d.d.f.5.2.c.5.2.c.0.d.d.0.0.9.1.c.2.ip6.arpa
b.d.d.0.0.d.d.0.0.e.4.d.d.f.5.2.c.5.2.c.0.d.d.0.0.9.1.c.2.ip6.arpa
/115 is not on a 4-bit boundary, so it takes 2 /116 zones.
Split into smaller subnets/124
/116 (2)/117 (4)/118 (8)/119 (16)/120 (32)/124 (512)/127 (4,096)/128 (8,192)

2c19:dd:c25:c25f:dd4e:dd:dd:a000/115 makes 512 subnets of /124; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:c25:c25f:dd4e:dd:dd:a000/1242c19:dd:c25:c25f:dd4e:dd:dd:a00f
22c19:dd:c25:c25f:dd4e:dd:dd:a010/1242c19:dd:c25:c25f:dd4e:dd:dd:a01f
32c19:dd:c25:c25f:dd4e:dd:dd:a020/1242c19:dd:c25:c25f:dd4e:dd:dd:a02f
42c19:dd:c25:c25f:dd4e:dd:dd:a030/1242c19:dd:c25:c25f:dd4e:dd:dd:a03f
52c19:dd:c25:c25f:dd4e:dd:dd:a040/1242c19:dd:c25:c25f:dd4e:dd:dd:a04f
62c19:dd:c25:c25f:dd4e:dd:dd:a050/1242c19:dd:c25:c25f:dd4e:dd:dd:a05f
72c19:dd:c25:c25f:dd4e:dd:dd:a060/1242c19:dd:c25:c25f:dd4e:dd:dd:a06f
82c19:dd:c25:c25f:dd4e:dd:dd:a070/1242c19:dd:c25:c25f:dd4e:dd:dd:a07f
92c19:dd:c25:c25f:dd4e:dd:dd:a080/1242c19:dd:c25:c25f:dd4e:dd:dd:a08f
102c19:dd:c25:c25f:dd4e:dd:dd:a090/1242c19:dd:c25:c25f:dd4e:dd:dd:a09f
112c19:dd:c25:c25f:dd4e:dd:dd:a0a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a0af
122c19:dd:c25:c25f:dd4e:dd:dd:a0b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a0bf
132c19:dd:c25:c25f:dd4e:dd:dd:a0c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a0cf
142c19:dd:c25:c25f:dd4e:dd:dd:a0d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a0df
152c19:dd:c25:c25f:dd4e:dd:dd:a0e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a0ef
162c19:dd:c25:c25f:dd4e:dd:dd:a0f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a0ff
172c19:dd:c25:c25f:dd4e:dd:dd:a100/1242c19:dd:c25:c25f:dd4e:dd:dd:a10f
182c19:dd:c25:c25f:dd4e:dd:dd:a110/1242c19:dd:c25:c25f:dd4e:dd:dd:a11f
192c19:dd:c25:c25f:dd4e:dd:dd:a120/1242c19:dd:c25:c25f:dd4e:dd:dd:a12f
202c19:dd:c25:c25f:dd4e:dd:dd:a130/1242c19:dd:c25:c25f:dd4e:dd:dd:a13f
212c19:dd:c25:c25f:dd4e:dd:dd:a140/1242c19:dd:c25:c25f:dd4e:dd:dd:a14f
222c19:dd:c25:c25f:dd4e:dd:dd:a150/1242c19:dd:c25:c25f:dd4e:dd:dd:a15f
232c19:dd:c25:c25f:dd4e:dd:dd:a160/1242c19:dd:c25:c25f:dd4e:dd:dd:a16f
242c19:dd:c25:c25f:dd4e:dd:dd:a170/1242c19:dd:c25:c25f:dd4e:dd:dd:a17f
252c19:dd:c25:c25f:dd4e:dd:dd:a180/1242c19:dd:c25:c25f:dd4e:dd:dd:a18f
262c19:dd:c25:c25f:dd4e:dd:dd:a190/1242c19:dd:c25:c25f:dd4e:dd:dd:a19f
272c19:dd:c25:c25f:dd4e:dd:dd:a1a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a1af
282c19:dd:c25:c25f:dd4e:dd:dd:a1b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a1bf
292c19:dd:c25:c25f:dd4e:dd:dd:a1c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a1cf
302c19:dd:c25:c25f:dd4e:dd:dd:a1d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a1df
312c19:dd:c25:c25f:dd4e:dd:dd:a1e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a1ef
322c19:dd:c25:c25f:dd4e:dd:dd:a1f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a1ff
332c19:dd:c25:c25f:dd4e:dd:dd:a200/1242c19:dd:c25:c25f:dd4e:dd:dd:a20f
342c19:dd:c25:c25f:dd4e:dd:dd:a210/1242c19:dd:c25:c25f:dd4e:dd:dd:a21f
352c19:dd:c25:c25f:dd4e:dd:dd:a220/1242c19:dd:c25:c25f:dd4e:dd:dd:a22f
362c19:dd:c25:c25f:dd4e:dd:dd:a230/1242c19:dd:c25:c25f:dd4e:dd:dd:a23f
372c19:dd:c25:c25f:dd4e:dd:dd:a240/1242c19:dd:c25:c25f:dd4e:dd:dd:a24f
382c19:dd:c25:c25f:dd4e:dd:dd:a250/1242c19:dd:c25:c25f:dd4e:dd:dd:a25f
392c19:dd:c25:c25f:dd4e:dd:dd:a260/1242c19:dd:c25:c25f:dd4e:dd:dd:a26f
402c19:dd:c25:c25f:dd4e:dd:dd:a270/1242c19:dd:c25:c25f:dd4e:dd:dd:a27f
412c19:dd:c25:c25f:dd4e:dd:dd:a280/1242c19:dd:c25:c25f:dd4e:dd:dd:a28f
422c19:dd:c25:c25f:dd4e:dd:dd:a290/1242c19:dd:c25:c25f:dd4e:dd:dd:a29f
432c19:dd:c25:c25f:dd4e:dd:dd:a2a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a2af
442c19:dd:c25:c25f:dd4e:dd:dd:a2b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a2bf
452c19:dd:c25:c25f:dd4e:dd:dd:a2c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a2cf
462c19:dd:c25:c25f:dd4e:dd:dd:a2d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a2df
472c19:dd:c25:c25f:dd4e:dd:dd:a2e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a2ef
482c19:dd:c25:c25f:dd4e:dd:dd:a2f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a2ff
492c19:dd:c25:c25f:dd4e:dd:dd:a300/1242c19:dd:c25:c25f:dd4e:dd:dd:a30f
502c19:dd:c25:c25f:dd4e:dd:dd:a310/1242c19:dd:c25:c25f:dd4e:dd:dd:a31f
512c19:dd:c25:c25f:dd4e:dd:dd:a320/1242c19:dd:c25:c25f:dd4e:dd:dd:a32f
522c19:dd:c25:c25f:dd4e:dd:dd:a330/1242c19:dd:c25:c25f:dd4e:dd:dd:a33f
532c19:dd:c25:c25f:dd4e:dd:dd:a340/1242c19:dd:c25:c25f:dd4e:dd:dd:a34f
542c19:dd:c25:c25f:dd4e:dd:dd:a350/1242c19:dd:c25:c25f:dd4e:dd:dd:a35f
552c19:dd:c25:c25f:dd4e:dd:dd:a360/1242c19:dd:c25:c25f:dd4e:dd:dd:a36f
562c19:dd:c25:c25f:dd4e:dd:dd:a370/1242c19:dd:c25:c25f:dd4e:dd:dd:a37f
572c19:dd:c25:c25f:dd4e:dd:dd:a380/1242c19:dd:c25:c25f:dd4e:dd:dd:a38f
582c19:dd:c25:c25f:dd4e:dd:dd:a390/1242c19:dd:c25:c25f:dd4e:dd:dd:a39f
592c19:dd:c25:c25f:dd4e:dd:dd:a3a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a3af
602c19:dd:c25:c25f:dd4e:dd:dd:a3b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a3bf
612c19:dd:c25:c25f:dd4e:dd:dd:a3c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a3cf
622c19:dd:c25:c25f:dd4e:dd:dd:a3d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a3df
632c19:dd:c25:c25f:dd4e:dd:dd:a3e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a3ef
642c19:dd:c25:c25f:dd4e:dd:dd:a3f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a3ff
652c19:dd:c25:c25f:dd4e:dd:dd:a400/1242c19:dd:c25:c25f:dd4e:dd:dd:a40f
662c19:dd:c25:c25f:dd4e:dd:dd:a410/1242c19:dd:c25:c25f:dd4e:dd:dd:a41f
672c19:dd:c25:c25f:dd4e:dd:dd:a420/1242c19:dd:c25:c25f:dd4e:dd:dd:a42f
682c19:dd:c25:c25f:dd4e:dd:dd:a430/1242c19:dd:c25:c25f:dd4e:dd:dd:a43f
692c19:dd:c25:c25f:dd4e:dd:dd:a440/1242c19:dd:c25:c25f:dd4e:dd:dd:a44f
702c19:dd:c25:c25f:dd4e:dd:dd:a450/1242c19:dd:c25:c25f:dd4e:dd:dd:a45f
712c19:dd:c25:c25f:dd4e:dd:dd:a460/1242c19:dd:c25:c25f:dd4e:dd:dd:a46f
722c19:dd:c25:c25f:dd4e:dd:dd:a470/1242c19:dd:c25:c25f:dd4e:dd:dd:a47f
732c19:dd:c25:c25f:dd4e:dd:dd:a480/1242c19:dd:c25:c25f:dd4e:dd:dd:a48f
742c19:dd:c25:c25f:dd4e:dd:dd:a490/1242c19:dd:c25:c25f:dd4e:dd:dd:a49f
752c19:dd:c25:c25f:dd4e:dd:dd:a4a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a4af
762c19:dd:c25:c25f:dd4e:dd:dd:a4b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a4bf
772c19:dd:c25:c25f:dd4e:dd:dd:a4c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a4cf
782c19:dd:c25:c25f:dd4e:dd:dd:a4d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a4df
792c19:dd:c25:c25f:dd4e:dd:dd:a4e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a4ef
802c19:dd:c25:c25f:dd4e:dd:dd:a4f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a4ff
812c19:dd:c25:c25f:dd4e:dd:dd:a500/1242c19:dd:c25:c25f:dd4e:dd:dd:a50f
822c19:dd:c25:c25f:dd4e:dd:dd:a510/1242c19:dd:c25:c25f:dd4e:dd:dd:a51f
832c19:dd:c25:c25f:dd4e:dd:dd:a520/1242c19:dd:c25:c25f:dd4e:dd:dd:a52f
842c19:dd:c25:c25f:dd4e:dd:dd:a530/1242c19:dd:c25:c25f:dd4e:dd:dd:a53f
852c19:dd:c25:c25f:dd4e:dd:dd:a540/1242c19:dd:c25:c25f:dd4e:dd:dd:a54f
862c19:dd:c25:c25f:dd4e:dd:dd:a550/1242c19:dd:c25:c25f:dd4e:dd:dd:a55f
872c19:dd:c25:c25f:dd4e:dd:dd:a560/1242c19:dd:c25:c25f:dd4e:dd:dd:a56f
882c19:dd:c25:c25f:dd4e:dd:dd:a570/1242c19:dd:c25:c25f:dd4e:dd:dd:a57f
892c19:dd:c25:c25f:dd4e:dd:dd:a580/1242c19:dd:c25:c25f:dd4e:dd:dd:a58f
902c19:dd:c25:c25f:dd4e:dd:dd:a590/1242c19:dd:c25:c25f:dd4e:dd:dd:a59f
912c19:dd:c25:c25f:dd4e:dd:dd:a5a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a5af
922c19:dd:c25:c25f:dd4e:dd:dd:a5b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a5bf
932c19:dd:c25:c25f:dd4e:dd:dd:a5c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a5cf
942c19:dd:c25:c25f:dd4e:dd:dd:a5d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a5df
952c19:dd:c25:c25f:dd4e:dd:dd:a5e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a5ef
962c19:dd:c25:c25f:dd4e:dd:dd:a5f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a5ff
972c19:dd:c25:c25f:dd4e:dd:dd:a600/1242c19:dd:c25:c25f:dd4e:dd:dd:a60f
982c19:dd:c25:c25f:dd4e:dd:dd:a610/1242c19:dd:c25:c25f:dd4e:dd:dd:a61f
992c19:dd:c25:c25f:dd4e:dd:dd:a620/1242c19:dd:c25:c25f:dd4e:dd:dd:a62f
1002c19:dd:c25:c25f:dd4e:dd:dd:a630/1242c19:dd:c25:c25f:dd4e:dd:dd:a63f
1012c19:dd:c25:c25f:dd4e:dd:dd:a640/1242c19:dd:c25:c25f:dd4e:dd:dd:a64f
1022c19:dd:c25:c25f:dd4e:dd:dd:a650/1242c19:dd:c25:c25f:dd4e:dd:dd:a65f
1032c19:dd:c25:c25f:dd4e:dd:dd:a660/1242c19:dd:c25:c25f:dd4e:dd:dd:a66f
1042c19:dd:c25:c25f:dd4e:dd:dd:a670/1242c19:dd:c25:c25f:dd4e:dd:dd:a67f
1052c19:dd:c25:c25f:dd4e:dd:dd:a680/1242c19:dd:c25:c25f:dd4e:dd:dd:a68f
1062c19:dd:c25:c25f:dd4e:dd:dd:a690/1242c19:dd:c25:c25f:dd4e:dd:dd:a69f
1072c19:dd:c25:c25f:dd4e:dd:dd:a6a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a6af
1082c19:dd:c25:c25f:dd4e:dd:dd:a6b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a6bf
1092c19:dd:c25:c25f:dd4e:dd:dd:a6c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a6cf
1102c19:dd:c25:c25f:dd4e:dd:dd:a6d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a6df
1112c19:dd:c25:c25f:dd4e:dd:dd:a6e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a6ef
1122c19:dd:c25:c25f:dd4e:dd:dd:a6f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a6ff
1132c19:dd:c25:c25f:dd4e:dd:dd:a700/1242c19:dd:c25:c25f:dd4e:dd:dd:a70f
1142c19:dd:c25:c25f:dd4e:dd:dd:a710/1242c19:dd:c25:c25f:dd4e:dd:dd:a71f
1152c19:dd:c25:c25f:dd4e:dd:dd:a720/1242c19:dd:c25:c25f:dd4e:dd:dd:a72f
1162c19:dd:c25:c25f:dd4e:dd:dd:a730/1242c19:dd:c25:c25f:dd4e:dd:dd:a73f
1172c19:dd:c25:c25f:dd4e:dd:dd:a740/1242c19:dd:c25:c25f:dd4e:dd:dd:a74f
1182c19:dd:c25:c25f:dd4e:dd:dd:a750/1242c19:dd:c25:c25f:dd4e:dd:dd:a75f
1192c19:dd:c25:c25f:dd4e:dd:dd:a760/1242c19:dd:c25:c25f:dd4e:dd:dd:a76f
1202c19:dd:c25:c25f:dd4e:dd:dd:a770/1242c19:dd:c25:c25f:dd4e:dd:dd:a77f
1212c19:dd:c25:c25f:dd4e:dd:dd:a780/1242c19:dd:c25:c25f:dd4e:dd:dd:a78f
1222c19:dd:c25:c25f:dd4e:dd:dd:a790/1242c19:dd:c25:c25f:dd4e:dd:dd:a79f
1232c19:dd:c25:c25f:dd4e:dd:dd:a7a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a7af
1242c19:dd:c25:c25f:dd4e:dd:dd:a7b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a7bf
1252c19:dd:c25:c25f:dd4e:dd:dd:a7c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a7cf
1262c19:dd:c25:c25f:dd4e:dd:dd:a7d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a7df
1272c19:dd:c25:c25f:dd4e:dd:dd:a7e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a7ef
1282c19:dd:c25:c25f:dd4e:dd:dd:a7f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a7ff
1292c19:dd:c25:c25f:dd4e:dd:dd:a800/1242c19:dd:c25:c25f:dd4e:dd:dd:a80f
1302c19:dd:c25:c25f:dd4e:dd:dd:a810/1242c19:dd:c25:c25f:dd4e:dd:dd:a81f
1312c19:dd:c25:c25f:dd4e:dd:dd:a820/1242c19:dd:c25:c25f:dd4e:dd:dd:a82f
1322c19:dd:c25:c25f:dd4e:dd:dd:a830/1242c19:dd:c25:c25f:dd4e:dd:dd:a83f
1332c19:dd:c25:c25f:dd4e:dd:dd:a840/1242c19:dd:c25:c25f:dd4e:dd:dd:a84f
1342c19:dd:c25:c25f:dd4e:dd:dd:a850/1242c19:dd:c25:c25f:dd4e:dd:dd:a85f
1352c19:dd:c25:c25f:dd4e:dd:dd:a860/1242c19:dd:c25:c25f:dd4e:dd:dd:a86f
1362c19:dd:c25:c25f:dd4e:dd:dd:a870/1242c19:dd:c25:c25f:dd4e:dd:dd:a87f
1372c19:dd:c25:c25f:dd4e:dd:dd:a880/1242c19:dd:c25:c25f:dd4e:dd:dd:a88f
1382c19:dd:c25:c25f:dd4e:dd:dd:a890/1242c19:dd:c25:c25f:dd4e:dd:dd:a89f
1392c19:dd:c25:c25f:dd4e:dd:dd:a8a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a8af
1402c19:dd:c25:c25f:dd4e:dd:dd:a8b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a8bf
1412c19:dd:c25:c25f:dd4e:dd:dd:a8c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a8cf
1422c19:dd:c25:c25f:dd4e:dd:dd:a8d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a8df
1432c19:dd:c25:c25f:dd4e:dd:dd:a8e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a8ef
1442c19:dd:c25:c25f:dd4e:dd:dd:a8f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a8ff
1452c19:dd:c25:c25f:dd4e:dd:dd:a900/1242c19:dd:c25:c25f:dd4e:dd:dd:a90f
1462c19:dd:c25:c25f:dd4e:dd:dd:a910/1242c19:dd:c25:c25f:dd4e:dd:dd:a91f
1472c19:dd:c25:c25f:dd4e:dd:dd:a920/1242c19:dd:c25:c25f:dd4e:dd:dd:a92f
1482c19:dd:c25:c25f:dd4e:dd:dd:a930/1242c19:dd:c25:c25f:dd4e:dd:dd:a93f
1492c19:dd:c25:c25f:dd4e:dd:dd:a940/1242c19:dd:c25:c25f:dd4e:dd:dd:a94f
1502c19:dd:c25:c25f:dd4e:dd:dd:a950/1242c19:dd:c25:c25f:dd4e:dd:dd:a95f
1512c19:dd:c25:c25f:dd4e:dd:dd:a960/1242c19:dd:c25:c25f:dd4e:dd:dd:a96f
1522c19:dd:c25:c25f:dd4e:dd:dd:a970/1242c19:dd:c25:c25f:dd4e:dd:dd:a97f
1532c19:dd:c25:c25f:dd4e:dd:dd:a980/1242c19:dd:c25:c25f:dd4e:dd:dd:a98f
1542c19:dd:c25:c25f:dd4e:dd:dd:a990/1242c19:dd:c25:c25f:dd4e:dd:dd:a99f
1552c19:dd:c25:c25f:dd4e:dd:dd:a9a0/1242c19:dd:c25:c25f:dd4e:dd:dd:a9af
1562c19:dd:c25:c25f:dd4e:dd:dd:a9b0/1242c19:dd:c25:c25f:dd4e:dd:dd:a9bf
1572c19:dd:c25:c25f:dd4e:dd:dd:a9c0/1242c19:dd:c25:c25f:dd4e:dd:dd:a9cf
1582c19:dd:c25:c25f:dd4e:dd:dd:a9d0/1242c19:dd:c25:c25f:dd4e:dd:dd:a9df
1592c19:dd:c25:c25f:dd4e:dd:dd:a9e0/1242c19:dd:c25:c25f:dd4e:dd:dd:a9ef
1602c19:dd:c25:c25f:dd4e:dd:dd:a9f0/1242c19:dd:c25:c25f:dd4e:dd:dd:a9ff
1612c19:dd:c25:c25f:dd4e:dd:dd:aa00/1242c19:dd:c25:c25f:dd4e:dd:dd:aa0f
1622c19:dd:c25:c25f:dd4e:dd:dd:aa10/1242c19:dd:c25:c25f:dd4e:dd:dd:aa1f
1632c19:dd:c25:c25f:dd4e:dd:dd:aa20/1242c19:dd:c25:c25f:dd4e:dd:dd:aa2f
1642c19:dd:c25:c25f:dd4e:dd:dd:aa30/1242c19:dd:c25:c25f:dd4e:dd:dd:aa3f
1652c19:dd:c25:c25f:dd4e:dd:dd:aa40/1242c19:dd:c25:c25f:dd4e:dd:dd:aa4f
1662c19:dd:c25:c25f:dd4e:dd:dd:aa50/1242c19:dd:c25:c25f:dd4e:dd:dd:aa5f
1672c19:dd:c25:c25f:dd4e:dd:dd:aa60/1242c19:dd:c25:c25f:dd4e:dd:dd:aa6f
1682c19:dd:c25:c25f:dd4e:dd:dd:aa70/1242c19:dd:c25:c25f:dd4e:dd:dd:aa7f
1692c19:dd:c25:c25f:dd4e:dd:dd:aa80/1242c19:dd:c25:c25f:dd4e:dd:dd:aa8f
1702c19:dd:c25:c25f:dd4e:dd:dd:aa90/1242c19:dd:c25:c25f:dd4e:dd:dd:aa9f
1712c19:dd:c25:c25f:dd4e:dd:dd:aaa0/1242c19:dd:c25:c25f:dd4e:dd:dd:aaaf
1722c19:dd:c25:c25f:dd4e:dd:dd:aab0/1242c19:dd:c25:c25f:dd4e:dd:dd:aabf
1732c19:dd:c25:c25f:dd4e:dd:dd:aac0/1242c19:dd:c25:c25f:dd4e:dd:dd:aacf
1742c19:dd:c25:c25f:dd4e:dd:dd:aad0/1242c19:dd:c25:c25f:dd4e:dd:dd:aadf
1752c19:dd:c25:c25f:dd4e:dd:dd:aae0/1242c19:dd:c25:c25f:dd4e:dd:dd:aaef
1762c19:dd:c25:c25f:dd4e:dd:dd:aaf0/1242c19:dd:c25:c25f:dd4e:dd:dd:aaff
1772c19:dd:c25:c25f:dd4e:dd:dd:ab00/1242c19:dd:c25:c25f:dd4e:dd:dd:ab0f
1782c19:dd:c25:c25f:dd4e:dd:dd:ab10/1242c19:dd:c25:c25f:dd4e:dd:dd:ab1f
1792c19:dd:c25:c25f:dd4e:dd:dd:ab20/1242c19:dd:c25:c25f:dd4e:dd:dd:ab2f
1802c19:dd:c25:c25f:dd4e:dd:dd:ab30/1242c19:dd:c25:c25f:dd4e:dd:dd:ab3f
1812c19:dd:c25:c25f:dd4e:dd:dd:ab40/1242c19:dd:c25:c25f:dd4e:dd:dd:ab4f
1822c19:dd:c25:c25f:dd4e:dd:dd:ab50/1242c19:dd:c25:c25f:dd4e:dd:dd:ab5f
1832c19:dd:c25:c25f:dd4e:dd:dd:ab60/1242c19:dd:c25:c25f:dd4e:dd:dd:ab6f
1842c19:dd:c25:c25f:dd4e:dd:dd:ab70/1242c19:dd:c25:c25f:dd4e:dd:dd:ab7f
1852c19:dd:c25:c25f:dd4e:dd:dd:ab80/1242c19:dd:c25:c25f:dd4e:dd:dd:ab8f
1862c19:dd:c25:c25f:dd4e:dd:dd:ab90/1242c19:dd:c25:c25f:dd4e:dd:dd:ab9f
1872c19:dd:c25:c25f:dd4e:dd:dd:aba0/1242c19:dd:c25:c25f:dd4e:dd:dd:abaf
1882c19:dd:c25:c25f:dd4e:dd:dd:abb0/1242c19:dd:c25:c25f:dd4e:dd:dd:abbf
1892c19:dd:c25:c25f:dd4e:dd:dd:abc0/1242c19:dd:c25:c25f:dd4e:dd:dd:abcf
1902c19:dd:c25:c25f:dd4e:dd:dd:abd0/1242c19:dd:c25:c25f:dd4e:dd:dd:abdf
1912c19:dd:c25:c25f:dd4e:dd:dd:abe0/1242c19:dd:c25:c25f:dd4e:dd:dd:abef
1922c19:dd:c25:c25f:dd4e:dd:dd:abf0/1242c19:dd:c25:c25f:dd4e:dd:dd:abff
1932c19:dd:c25:c25f:dd4e:dd:dd:ac00/1242c19:dd:c25:c25f:dd4e:dd:dd:ac0f
1942c19:dd:c25:c25f:dd4e:dd:dd:ac10/1242c19:dd:c25:c25f:dd4e:dd:dd:ac1f
1952c19:dd:c25:c25f:dd4e:dd:dd:ac20/1242c19:dd:c25:c25f:dd4e:dd:dd:ac2f
1962c19:dd:c25:c25f:dd4e:dd:dd:ac30/1242c19:dd:c25:c25f:dd4e:dd:dd:ac3f
1972c19:dd:c25:c25f:dd4e:dd:dd:ac40/1242c19:dd:c25:c25f:dd4e:dd:dd:ac4f
1982c19:dd:c25:c25f:dd4e:dd:dd:ac50/1242c19:dd:c25:c25f:dd4e:dd:dd:ac5f
1992c19:dd:c25:c25f:dd4e:dd:dd:ac60/1242c19:dd:c25:c25f:dd4e:dd:dd:ac6f
2002c19:dd:c25:c25f:dd4e:dd:dd:ac70/1242c19:dd:c25:c25f:dd4e:dd:dd:ac7f
2012c19:dd:c25:c25f:dd4e:dd:dd:ac80/1242c19:dd:c25:c25f:dd4e:dd:dd:ac8f
2022c19:dd:c25:c25f:dd4e:dd:dd:ac90/1242c19:dd:c25:c25f:dd4e:dd:dd:ac9f
2032c19:dd:c25:c25f:dd4e:dd:dd:aca0/1242c19:dd:c25:c25f:dd4e:dd:dd:acaf
2042c19:dd:c25:c25f:dd4e:dd:dd:acb0/1242c19:dd:c25:c25f:dd4e:dd:dd:acbf
2052c19:dd:c25:c25f:dd4e:dd:dd:acc0/1242c19:dd:c25:c25f:dd4e:dd:dd:accf
2062c19:dd:c25:c25f:dd4e:dd:dd:acd0/1242c19:dd:c25:c25f:dd4e:dd:dd:acdf
2072c19:dd:c25:c25f:dd4e:dd:dd:ace0/1242c19:dd:c25:c25f:dd4e:dd:dd:acef
2082c19:dd:c25:c25f:dd4e:dd:dd:acf0/1242c19:dd:c25:c25f:dd4e:dd:dd:acff
2092c19:dd:c25:c25f:dd4e:dd:dd:ad00/1242c19:dd:c25:c25f:dd4e:dd:dd:ad0f
2102c19:dd:c25:c25f:dd4e:dd:dd:ad10/1242c19:dd:c25:c25f:dd4e:dd:dd:ad1f
2112c19:dd:c25:c25f:dd4e:dd:dd:ad20/1242c19:dd:c25:c25f:dd4e:dd:dd:ad2f
2122c19:dd:c25:c25f:dd4e:dd:dd:ad30/1242c19:dd:c25:c25f:dd4e:dd:dd:ad3f
2132c19:dd:c25:c25f:dd4e:dd:dd:ad40/1242c19:dd:c25:c25f:dd4e:dd:dd:ad4f
2142c19:dd:c25:c25f:dd4e:dd:dd:ad50/1242c19:dd:c25:c25f:dd4e:dd:dd:ad5f
2152c19:dd:c25:c25f:dd4e:dd:dd:ad60/1242c19:dd:c25:c25f:dd4e:dd:dd:ad6f
2162c19:dd:c25:c25f:dd4e:dd:dd:ad70/1242c19:dd:c25:c25f:dd4e:dd:dd:ad7f
2172c19:dd:c25:c25f:dd4e:dd:dd:ad80/1242c19:dd:c25:c25f:dd4e:dd:dd:ad8f
2182c19:dd:c25:c25f:dd4e:dd:dd:ad90/1242c19:dd:c25:c25f:dd4e:dd:dd:ad9f
2192c19:dd:c25:c25f:dd4e:dd:dd:ada0/1242c19:dd:c25:c25f:dd4e:dd:dd:adaf
2202c19:dd:c25:c25f:dd4e:dd:dd:adb0/1242c19:dd:c25:c25f:dd4e:dd:dd:adbf
2212c19:dd:c25:c25f:dd4e:dd:dd:adc0/1242c19:dd:c25:c25f:dd4e:dd:dd:adcf
2222c19:dd:c25:c25f:dd4e:dd:dd:add0/1242c19:dd:c25:c25f:dd4e:dd:dd:addf
2232c19:dd:c25:c25f:dd4e:dd:dd:ade0/1242c19:dd:c25:c25f:dd4e:dd:dd:adef
2242c19:dd:c25:c25f:dd4e:dd:dd:adf0/1242c19:dd:c25:c25f:dd4e:dd:dd:adff
2252c19:dd:c25:c25f:dd4e:dd:dd:ae00/1242c19:dd:c25:c25f:dd4e:dd:dd:ae0f
2262c19:dd:c25:c25f:dd4e:dd:dd:ae10/1242c19:dd:c25:c25f:dd4e:dd:dd:ae1f
2272c19:dd:c25:c25f:dd4e:dd:dd:ae20/1242c19:dd:c25:c25f:dd4e:dd:dd:ae2f
2282c19:dd:c25:c25f:dd4e:dd:dd:ae30/1242c19:dd:c25:c25f:dd4e:dd:dd:ae3f
2292c19:dd:c25:c25f:dd4e:dd:dd:ae40/1242c19:dd:c25:c25f:dd4e:dd:dd:ae4f
2302c19:dd:c25:c25f:dd4e:dd:dd:ae50/1242c19:dd:c25:c25f:dd4e:dd:dd:ae5f
2312c19:dd:c25:c25f:dd4e:dd:dd:ae60/1242c19:dd:c25:c25f:dd4e:dd:dd:ae6f
2322c19:dd:c25:c25f:dd4e:dd:dd:ae70/1242c19:dd:c25:c25f:dd4e:dd:dd:ae7f
2332c19:dd:c25:c25f:dd4e:dd:dd:ae80/1242c19:dd:c25:c25f:dd4e:dd:dd:ae8f
2342c19:dd:c25:c25f:dd4e:dd:dd:ae90/1242c19:dd:c25:c25f:dd4e:dd:dd:ae9f
2352c19:dd:c25:c25f:dd4e:dd:dd:aea0/1242c19:dd:c25:c25f:dd4e:dd:dd:aeaf
2362c19:dd:c25:c25f:dd4e:dd:dd:aeb0/1242c19:dd:c25:c25f:dd4e:dd:dd:aebf
2372c19:dd:c25:c25f:dd4e:dd:dd:aec0/1242c19:dd:c25:c25f:dd4e:dd:dd:aecf
2382c19:dd:c25:c25f:dd4e:dd:dd:aed0/1242c19:dd:c25:c25f:dd4e:dd:dd:aedf
2392c19:dd:c25:c25f:dd4e:dd:dd:aee0/1242c19:dd:c25:c25f:dd4e:dd:dd:aeef
2402c19:dd:c25:c25f:dd4e:dd:dd:aef0/1242c19:dd:c25:c25f:dd4e:dd:dd:aeff
2412c19:dd:c25:c25f:dd4e:dd:dd:af00/1242c19:dd:c25:c25f:dd4e:dd:dd:af0f
2422c19:dd:c25:c25f:dd4e:dd:dd:af10/1242c19:dd:c25:c25f:dd4e:dd:dd:af1f
2432c19:dd:c25:c25f:dd4e:dd:dd:af20/1242c19:dd:c25:c25f:dd4e:dd:dd:af2f
2442c19:dd:c25:c25f:dd4e:dd:dd:af30/1242c19:dd:c25:c25f:dd4e:dd:dd:af3f
2452c19:dd:c25:c25f:dd4e:dd:dd:af40/1242c19:dd:c25:c25f:dd4e:dd:dd:af4f
2462c19:dd:c25:c25f:dd4e:dd:dd:af50/1242c19:dd:c25:c25f:dd4e:dd:dd:af5f
2472c19:dd:c25:c25f:dd4e:dd:dd:af60/1242c19:dd:c25:c25f:dd4e:dd:dd:af6f
2482c19:dd:c25:c25f:dd4e:dd:dd:af70/1242c19:dd:c25:c25f:dd4e:dd:dd:af7f
2492c19:dd:c25:c25f:dd4e:dd:dd:af80/1242c19:dd:c25:c25f:dd4e:dd:dd:af8f
2502c19:dd:c25:c25f:dd4e:dd:dd:af90/1242c19:dd:c25:c25f:dd4e:dd:dd:af9f
2512c19:dd:c25:c25f:dd4e:dd:dd:afa0/1242c19:dd:c25:c25f:dd4e:dd:dd:afaf
2522c19:dd:c25:c25f:dd4e:dd:dd:afb0/1242c19:dd:c25:c25f:dd4e:dd:dd:afbf
2532c19:dd:c25:c25f:dd4e:dd:dd:afc0/1242c19:dd:c25:c25f:dd4e:dd:dd:afcf
2542c19:dd:c25:c25f:dd4e:dd:dd:afd0/1242c19:dd:c25:c25f:dd4e:dd:dd:afdf
2552c19:dd:c25:c25f:dd4e:dd:dd:afe0/1242c19:dd:c25:c25f:dd4e:dd:dd:afef
2562c19:dd:c25:c25f:dd4e:dd:dd:aff0/1242c19:dd:c25:c25f:dd4e:dd:dd:afff

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.