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:d9bd:2000/116
First address
2c19:dd:d9:dd:c25:c25:d9bd:2000
Last address
2c19:dd:d9:dd:c25:c25:d9bd:2fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:d9bd:2000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
2.d.b.9.d.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:d9bd:2000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:d9bd:2000/1242c19:dd:d9:dd:c25:c25:d9bd:200f
22c19:dd:d9:dd:c25:c25:d9bd:2010/1242c19:dd:d9:dd:c25:c25:d9bd:201f
32c19:dd:d9:dd:c25:c25:d9bd:2020/1242c19:dd:d9:dd:c25:c25:d9bd:202f
42c19:dd:d9:dd:c25:c25:d9bd:2030/1242c19:dd:d9:dd:c25:c25:d9bd:203f
52c19:dd:d9:dd:c25:c25:d9bd:2040/1242c19:dd:d9:dd:c25:c25:d9bd:204f
62c19:dd:d9:dd:c25:c25:d9bd:2050/1242c19:dd:d9:dd:c25:c25:d9bd:205f
72c19:dd:d9:dd:c25:c25:d9bd:2060/1242c19:dd:d9:dd:c25:c25:d9bd:206f
82c19:dd:d9:dd:c25:c25:d9bd:2070/1242c19:dd:d9:dd:c25:c25:d9bd:207f
92c19:dd:d9:dd:c25:c25:d9bd:2080/1242c19:dd:d9:dd:c25:c25:d9bd:208f
102c19:dd:d9:dd:c25:c25:d9bd:2090/1242c19:dd:d9:dd:c25:c25:d9bd:209f
112c19:dd:d9:dd:c25:c25:d9bd:20a0/1242c19:dd:d9:dd:c25:c25:d9bd:20af
122c19:dd:d9:dd:c25:c25:d9bd:20b0/1242c19:dd:d9:dd:c25:c25:d9bd:20bf
132c19:dd:d9:dd:c25:c25:d9bd:20c0/1242c19:dd:d9:dd:c25:c25:d9bd:20cf
142c19:dd:d9:dd:c25:c25:d9bd:20d0/1242c19:dd:d9:dd:c25:c25:d9bd:20df
152c19:dd:d9:dd:c25:c25:d9bd:20e0/1242c19:dd:d9:dd:c25:c25:d9bd:20ef
162c19:dd:d9:dd:c25:c25:d9bd:20f0/1242c19:dd:d9:dd:c25:c25:d9bd:20ff
172c19:dd:d9:dd:c25:c25:d9bd:2100/1242c19:dd:d9:dd:c25:c25:d9bd:210f
182c19:dd:d9:dd:c25:c25:d9bd:2110/1242c19:dd:d9:dd:c25:c25:d9bd:211f
192c19:dd:d9:dd:c25:c25:d9bd:2120/1242c19:dd:d9:dd:c25:c25:d9bd:212f
202c19:dd:d9:dd:c25:c25:d9bd:2130/1242c19:dd:d9:dd:c25:c25:d9bd:213f
212c19:dd:d9:dd:c25:c25:d9bd:2140/1242c19:dd:d9:dd:c25:c25:d9bd:214f
222c19:dd:d9:dd:c25:c25:d9bd:2150/1242c19:dd:d9:dd:c25:c25:d9bd:215f
232c19:dd:d9:dd:c25:c25:d9bd:2160/1242c19:dd:d9:dd:c25:c25:d9bd:216f
242c19:dd:d9:dd:c25:c25:d9bd:2170/1242c19:dd:d9:dd:c25:c25:d9bd:217f
252c19:dd:d9:dd:c25:c25:d9bd:2180/1242c19:dd:d9:dd:c25:c25:d9bd:218f
262c19:dd:d9:dd:c25:c25:d9bd:2190/1242c19:dd:d9:dd:c25:c25:d9bd:219f
272c19:dd:d9:dd:c25:c25:d9bd:21a0/1242c19:dd:d9:dd:c25:c25:d9bd:21af
282c19:dd:d9:dd:c25:c25:d9bd:21b0/1242c19:dd:d9:dd:c25:c25:d9bd:21bf
292c19:dd:d9:dd:c25:c25:d9bd:21c0/1242c19:dd:d9:dd:c25:c25:d9bd:21cf
302c19:dd:d9:dd:c25:c25:d9bd:21d0/1242c19:dd:d9:dd:c25:c25:d9bd:21df
312c19:dd:d9:dd:c25:c25:d9bd:21e0/1242c19:dd:d9:dd:c25:c25:d9bd:21ef
322c19:dd:d9:dd:c25:c25:d9bd:21f0/1242c19:dd:d9:dd:c25:c25:d9bd:21ff
332c19:dd:d9:dd:c25:c25:d9bd:2200/1242c19:dd:d9:dd:c25:c25:d9bd:220f
342c19:dd:d9:dd:c25:c25:d9bd:2210/1242c19:dd:d9:dd:c25:c25:d9bd:221f
352c19:dd:d9:dd:c25:c25:d9bd:2220/1242c19:dd:d9:dd:c25:c25:d9bd:222f
362c19:dd:d9:dd:c25:c25:d9bd:2230/1242c19:dd:d9:dd:c25:c25:d9bd:223f
372c19:dd:d9:dd:c25:c25:d9bd:2240/1242c19:dd:d9:dd:c25:c25:d9bd:224f
382c19:dd:d9:dd:c25:c25:d9bd:2250/1242c19:dd:d9:dd:c25:c25:d9bd:225f
392c19:dd:d9:dd:c25:c25:d9bd:2260/1242c19:dd:d9:dd:c25:c25:d9bd:226f
402c19:dd:d9:dd:c25:c25:d9bd:2270/1242c19:dd:d9:dd:c25:c25:d9bd:227f
412c19:dd:d9:dd:c25:c25:d9bd:2280/1242c19:dd:d9:dd:c25:c25:d9bd:228f
422c19:dd:d9:dd:c25:c25:d9bd:2290/1242c19:dd:d9:dd:c25:c25:d9bd:229f
432c19:dd:d9:dd:c25:c25:d9bd:22a0/1242c19:dd:d9:dd:c25:c25:d9bd:22af
442c19:dd:d9:dd:c25:c25:d9bd:22b0/1242c19:dd:d9:dd:c25:c25:d9bd:22bf
452c19:dd:d9:dd:c25:c25:d9bd:22c0/1242c19:dd:d9:dd:c25:c25:d9bd:22cf
462c19:dd:d9:dd:c25:c25:d9bd:22d0/1242c19:dd:d9:dd:c25:c25:d9bd:22df
472c19:dd:d9:dd:c25:c25:d9bd:22e0/1242c19:dd:d9:dd:c25:c25:d9bd:22ef
482c19:dd:d9:dd:c25:c25:d9bd:22f0/1242c19:dd:d9:dd:c25:c25:d9bd:22ff
492c19:dd:d9:dd:c25:c25:d9bd:2300/1242c19:dd:d9:dd:c25:c25:d9bd:230f
502c19:dd:d9:dd:c25:c25:d9bd:2310/1242c19:dd:d9:dd:c25:c25:d9bd:231f
512c19:dd:d9:dd:c25:c25:d9bd:2320/1242c19:dd:d9:dd:c25:c25:d9bd:232f
522c19:dd:d9:dd:c25:c25:d9bd:2330/1242c19:dd:d9:dd:c25:c25:d9bd:233f
532c19:dd:d9:dd:c25:c25:d9bd:2340/1242c19:dd:d9:dd:c25:c25:d9bd:234f
542c19:dd:d9:dd:c25:c25:d9bd:2350/1242c19:dd:d9:dd:c25:c25:d9bd:235f
552c19:dd:d9:dd:c25:c25:d9bd:2360/1242c19:dd:d9:dd:c25:c25:d9bd:236f
562c19:dd:d9:dd:c25:c25:d9bd:2370/1242c19:dd:d9:dd:c25:c25:d9bd:237f
572c19:dd:d9:dd:c25:c25:d9bd:2380/1242c19:dd:d9:dd:c25:c25:d9bd:238f
582c19:dd:d9:dd:c25:c25:d9bd:2390/1242c19:dd:d9:dd:c25:c25:d9bd:239f
592c19:dd:d9:dd:c25:c25:d9bd:23a0/1242c19:dd:d9:dd:c25:c25:d9bd:23af
602c19:dd:d9:dd:c25:c25:d9bd:23b0/1242c19:dd:d9:dd:c25:c25:d9bd:23bf
612c19:dd:d9:dd:c25:c25:d9bd:23c0/1242c19:dd:d9:dd:c25:c25:d9bd:23cf
622c19:dd:d9:dd:c25:c25:d9bd:23d0/1242c19:dd:d9:dd:c25:c25:d9bd:23df
632c19:dd:d9:dd:c25:c25:d9bd:23e0/1242c19:dd:d9:dd:c25:c25:d9bd:23ef
642c19:dd:d9:dd:c25:c25:d9bd:23f0/1242c19:dd:d9:dd:c25:c25:d9bd:23ff
652c19:dd:d9:dd:c25:c25:d9bd:2400/1242c19:dd:d9:dd:c25:c25:d9bd:240f
662c19:dd:d9:dd:c25:c25:d9bd:2410/1242c19:dd:d9:dd:c25:c25:d9bd:241f
672c19:dd:d9:dd:c25:c25:d9bd:2420/1242c19:dd:d9:dd:c25:c25:d9bd:242f
682c19:dd:d9:dd:c25:c25:d9bd:2430/1242c19:dd:d9:dd:c25:c25:d9bd:243f
692c19:dd:d9:dd:c25:c25:d9bd:2440/1242c19:dd:d9:dd:c25:c25:d9bd:244f
702c19:dd:d9:dd:c25:c25:d9bd:2450/1242c19:dd:d9:dd:c25:c25:d9bd:245f
712c19:dd:d9:dd:c25:c25:d9bd:2460/1242c19:dd:d9:dd:c25:c25:d9bd:246f
722c19:dd:d9:dd:c25:c25:d9bd:2470/1242c19:dd:d9:dd:c25:c25:d9bd:247f
732c19:dd:d9:dd:c25:c25:d9bd:2480/1242c19:dd:d9:dd:c25:c25:d9bd:248f
742c19:dd:d9:dd:c25:c25:d9bd:2490/1242c19:dd:d9:dd:c25:c25:d9bd:249f
752c19:dd:d9:dd:c25:c25:d9bd:24a0/1242c19:dd:d9:dd:c25:c25:d9bd:24af
762c19:dd:d9:dd:c25:c25:d9bd:24b0/1242c19:dd:d9:dd:c25:c25:d9bd:24bf
772c19:dd:d9:dd:c25:c25:d9bd:24c0/1242c19:dd:d9:dd:c25:c25:d9bd:24cf
782c19:dd:d9:dd:c25:c25:d9bd:24d0/1242c19:dd:d9:dd:c25:c25:d9bd:24df
792c19:dd:d9:dd:c25:c25:d9bd:24e0/1242c19:dd:d9:dd:c25:c25:d9bd:24ef
802c19:dd:d9:dd:c25:c25:d9bd:24f0/1242c19:dd:d9:dd:c25:c25:d9bd:24ff
812c19:dd:d9:dd:c25:c25:d9bd:2500/1242c19:dd:d9:dd:c25:c25:d9bd:250f
822c19:dd:d9:dd:c25:c25:d9bd:2510/1242c19:dd:d9:dd:c25:c25:d9bd:251f
832c19:dd:d9:dd:c25:c25:d9bd:2520/1242c19:dd:d9:dd:c25:c25:d9bd:252f
842c19:dd:d9:dd:c25:c25:d9bd:2530/1242c19:dd:d9:dd:c25:c25:d9bd:253f
852c19:dd:d9:dd:c25:c25:d9bd:2540/1242c19:dd:d9:dd:c25:c25:d9bd:254f
862c19:dd:d9:dd:c25:c25:d9bd:2550/1242c19:dd:d9:dd:c25:c25:d9bd:255f
872c19:dd:d9:dd:c25:c25:d9bd:2560/1242c19:dd:d9:dd:c25:c25:d9bd:256f
882c19:dd:d9:dd:c25:c25:d9bd:2570/1242c19:dd:d9:dd:c25:c25:d9bd:257f
892c19:dd:d9:dd:c25:c25:d9bd:2580/1242c19:dd:d9:dd:c25:c25:d9bd:258f
902c19:dd:d9:dd:c25:c25:d9bd:2590/1242c19:dd:d9:dd:c25:c25:d9bd:259f
912c19:dd:d9:dd:c25:c25:d9bd:25a0/1242c19:dd:d9:dd:c25:c25:d9bd:25af
922c19:dd:d9:dd:c25:c25:d9bd:25b0/1242c19:dd:d9:dd:c25:c25:d9bd:25bf
932c19:dd:d9:dd:c25:c25:d9bd:25c0/1242c19:dd:d9:dd:c25:c25:d9bd:25cf
942c19:dd:d9:dd:c25:c25:d9bd:25d0/1242c19:dd:d9:dd:c25:c25:d9bd:25df
952c19:dd:d9:dd:c25:c25:d9bd:25e0/1242c19:dd:d9:dd:c25:c25:d9bd:25ef
962c19:dd:d9:dd:c25:c25:d9bd:25f0/1242c19:dd:d9:dd:c25:c25:d9bd:25ff
972c19:dd:d9:dd:c25:c25:d9bd:2600/1242c19:dd:d9:dd:c25:c25:d9bd:260f
982c19:dd:d9:dd:c25:c25:d9bd:2610/1242c19:dd:d9:dd:c25:c25:d9bd:261f
992c19:dd:d9:dd:c25:c25:d9bd:2620/1242c19:dd:d9:dd:c25:c25:d9bd:262f
1002c19:dd:d9:dd:c25:c25:d9bd:2630/1242c19:dd:d9:dd:c25:c25:d9bd:263f
1012c19:dd:d9:dd:c25:c25:d9bd:2640/1242c19:dd:d9:dd:c25:c25:d9bd:264f
1022c19:dd:d9:dd:c25:c25:d9bd:2650/1242c19:dd:d9:dd:c25:c25:d9bd:265f
1032c19:dd:d9:dd:c25:c25:d9bd:2660/1242c19:dd:d9:dd:c25:c25:d9bd:266f
1042c19:dd:d9:dd:c25:c25:d9bd:2670/1242c19:dd:d9:dd:c25:c25:d9bd:267f
1052c19:dd:d9:dd:c25:c25:d9bd:2680/1242c19:dd:d9:dd:c25:c25:d9bd:268f
1062c19:dd:d9:dd:c25:c25:d9bd:2690/1242c19:dd:d9:dd:c25:c25:d9bd:269f
1072c19:dd:d9:dd:c25:c25:d9bd:26a0/1242c19:dd:d9:dd:c25:c25:d9bd:26af
1082c19:dd:d9:dd:c25:c25:d9bd:26b0/1242c19:dd:d9:dd:c25:c25:d9bd:26bf
1092c19:dd:d9:dd:c25:c25:d9bd:26c0/1242c19:dd:d9:dd:c25:c25:d9bd:26cf
1102c19:dd:d9:dd:c25:c25:d9bd:26d0/1242c19:dd:d9:dd:c25:c25:d9bd:26df
1112c19:dd:d9:dd:c25:c25:d9bd:26e0/1242c19:dd:d9:dd:c25:c25:d9bd:26ef
1122c19:dd:d9:dd:c25:c25:d9bd:26f0/1242c19:dd:d9:dd:c25:c25:d9bd:26ff
1132c19:dd:d9:dd:c25:c25:d9bd:2700/1242c19:dd:d9:dd:c25:c25:d9bd:270f
1142c19:dd:d9:dd:c25:c25:d9bd:2710/1242c19:dd:d9:dd:c25:c25:d9bd:271f
1152c19:dd:d9:dd:c25:c25:d9bd:2720/1242c19:dd:d9:dd:c25:c25:d9bd:272f
1162c19:dd:d9:dd:c25:c25:d9bd:2730/1242c19:dd:d9:dd:c25:c25:d9bd:273f
1172c19:dd:d9:dd:c25:c25:d9bd:2740/1242c19:dd:d9:dd:c25:c25:d9bd:274f
1182c19:dd:d9:dd:c25:c25:d9bd:2750/1242c19:dd:d9:dd:c25:c25:d9bd:275f
1192c19:dd:d9:dd:c25:c25:d9bd:2760/1242c19:dd:d9:dd:c25:c25:d9bd:276f
1202c19:dd:d9:dd:c25:c25:d9bd:2770/1242c19:dd:d9:dd:c25:c25:d9bd:277f
1212c19:dd:d9:dd:c25:c25:d9bd:2780/1242c19:dd:d9:dd:c25:c25:d9bd:278f
1222c19:dd:d9:dd:c25:c25:d9bd:2790/1242c19:dd:d9:dd:c25:c25:d9bd:279f
1232c19:dd:d9:dd:c25:c25:d9bd:27a0/1242c19:dd:d9:dd:c25:c25:d9bd:27af
1242c19:dd:d9:dd:c25:c25:d9bd:27b0/1242c19:dd:d9:dd:c25:c25:d9bd:27bf
1252c19:dd:d9:dd:c25:c25:d9bd:27c0/1242c19:dd:d9:dd:c25:c25:d9bd:27cf
1262c19:dd:d9:dd:c25:c25:d9bd:27d0/1242c19:dd:d9:dd:c25:c25:d9bd:27df
1272c19:dd:d9:dd:c25:c25:d9bd:27e0/1242c19:dd:d9:dd:c25:c25:d9bd:27ef
1282c19:dd:d9:dd:c25:c25:d9bd:27f0/1242c19:dd:d9:dd:c25:c25:d9bd:27ff
1292c19:dd:d9:dd:c25:c25:d9bd:2800/1242c19:dd:d9:dd:c25:c25:d9bd:280f
1302c19:dd:d9:dd:c25:c25:d9bd:2810/1242c19:dd:d9:dd:c25:c25:d9bd:281f
1312c19:dd:d9:dd:c25:c25:d9bd:2820/1242c19:dd:d9:dd:c25:c25:d9bd:282f
1322c19:dd:d9:dd:c25:c25:d9bd:2830/1242c19:dd:d9:dd:c25:c25:d9bd:283f
1332c19:dd:d9:dd:c25:c25:d9bd:2840/1242c19:dd:d9:dd:c25:c25:d9bd:284f
1342c19:dd:d9:dd:c25:c25:d9bd:2850/1242c19:dd:d9:dd:c25:c25:d9bd:285f
1352c19:dd:d9:dd:c25:c25:d9bd:2860/1242c19:dd:d9:dd:c25:c25:d9bd:286f
1362c19:dd:d9:dd:c25:c25:d9bd:2870/1242c19:dd:d9:dd:c25:c25:d9bd:287f
1372c19:dd:d9:dd:c25:c25:d9bd:2880/1242c19:dd:d9:dd:c25:c25:d9bd:288f
1382c19:dd:d9:dd:c25:c25:d9bd:2890/1242c19:dd:d9:dd:c25:c25:d9bd:289f
1392c19:dd:d9:dd:c25:c25:d9bd:28a0/1242c19:dd:d9:dd:c25:c25:d9bd:28af
1402c19:dd:d9:dd:c25:c25:d9bd:28b0/1242c19:dd:d9:dd:c25:c25:d9bd:28bf
1412c19:dd:d9:dd:c25:c25:d9bd:28c0/1242c19:dd:d9:dd:c25:c25:d9bd:28cf
1422c19:dd:d9:dd:c25:c25:d9bd:28d0/1242c19:dd:d9:dd:c25:c25:d9bd:28df
1432c19:dd:d9:dd:c25:c25:d9bd:28e0/1242c19:dd:d9:dd:c25:c25:d9bd:28ef
1442c19:dd:d9:dd:c25:c25:d9bd:28f0/1242c19:dd:d9:dd:c25:c25:d9bd:28ff
1452c19:dd:d9:dd:c25:c25:d9bd:2900/1242c19:dd:d9:dd:c25:c25:d9bd:290f
1462c19:dd:d9:dd:c25:c25:d9bd:2910/1242c19:dd:d9:dd:c25:c25:d9bd:291f
1472c19:dd:d9:dd:c25:c25:d9bd:2920/1242c19:dd:d9:dd:c25:c25:d9bd:292f
1482c19:dd:d9:dd:c25:c25:d9bd:2930/1242c19:dd:d9:dd:c25:c25:d9bd:293f
1492c19:dd:d9:dd:c25:c25:d9bd:2940/1242c19:dd:d9:dd:c25:c25:d9bd:294f
1502c19:dd:d9:dd:c25:c25:d9bd:2950/1242c19:dd:d9:dd:c25:c25:d9bd:295f
1512c19:dd:d9:dd:c25:c25:d9bd:2960/1242c19:dd:d9:dd:c25:c25:d9bd:296f
1522c19:dd:d9:dd:c25:c25:d9bd:2970/1242c19:dd:d9:dd:c25:c25:d9bd:297f
1532c19:dd:d9:dd:c25:c25:d9bd:2980/1242c19:dd:d9:dd:c25:c25:d9bd:298f
1542c19:dd:d9:dd:c25:c25:d9bd:2990/1242c19:dd:d9:dd:c25:c25:d9bd:299f
1552c19:dd:d9:dd:c25:c25:d9bd:29a0/1242c19:dd:d9:dd:c25:c25:d9bd:29af
1562c19:dd:d9:dd:c25:c25:d9bd:29b0/1242c19:dd:d9:dd:c25:c25:d9bd:29bf
1572c19:dd:d9:dd:c25:c25:d9bd:29c0/1242c19:dd:d9:dd:c25:c25:d9bd:29cf
1582c19:dd:d9:dd:c25:c25:d9bd:29d0/1242c19:dd:d9:dd:c25:c25:d9bd:29df
1592c19:dd:d9:dd:c25:c25:d9bd:29e0/1242c19:dd:d9:dd:c25:c25:d9bd:29ef
1602c19:dd:d9:dd:c25:c25:d9bd:29f0/1242c19:dd:d9:dd:c25:c25:d9bd:29ff
1612c19:dd:d9:dd:c25:c25:d9bd:2a00/1242c19:dd:d9:dd:c25:c25:d9bd:2a0f
1622c19:dd:d9:dd:c25:c25:d9bd:2a10/1242c19:dd:d9:dd:c25:c25:d9bd:2a1f
1632c19:dd:d9:dd:c25:c25:d9bd:2a20/1242c19:dd:d9:dd:c25:c25:d9bd:2a2f
1642c19:dd:d9:dd:c25:c25:d9bd:2a30/1242c19:dd:d9:dd:c25:c25:d9bd:2a3f
1652c19:dd:d9:dd:c25:c25:d9bd:2a40/1242c19:dd:d9:dd:c25:c25:d9bd:2a4f
1662c19:dd:d9:dd:c25:c25:d9bd:2a50/1242c19:dd:d9:dd:c25:c25:d9bd:2a5f
1672c19:dd:d9:dd:c25:c25:d9bd:2a60/1242c19:dd:d9:dd:c25:c25:d9bd:2a6f
1682c19:dd:d9:dd:c25:c25:d9bd:2a70/1242c19:dd:d9:dd:c25:c25:d9bd:2a7f
1692c19:dd:d9:dd:c25:c25:d9bd:2a80/1242c19:dd:d9:dd:c25:c25:d9bd:2a8f
1702c19:dd:d9:dd:c25:c25:d9bd:2a90/1242c19:dd:d9:dd:c25:c25:d9bd:2a9f
1712c19:dd:d9:dd:c25:c25:d9bd:2aa0/1242c19:dd:d9:dd:c25:c25:d9bd:2aaf
1722c19:dd:d9:dd:c25:c25:d9bd:2ab0/1242c19:dd:d9:dd:c25:c25:d9bd:2abf
1732c19:dd:d9:dd:c25:c25:d9bd:2ac0/1242c19:dd:d9:dd:c25:c25:d9bd:2acf
1742c19:dd:d9:dd:c25:c25:d9bd:2ad0/1242c19:dd:d9:dd:c25:c25:d9bd:2adf
1752c19:dd:d9:dd:c25:c25:d9bd:2ae0/1242c19:dd:d9:dd:c25:c25:d9bd:2aef
1762c19:dd:d9:dd:c25:c25:d9bd:2af0/1242c19:dd:d9:dd:c25:c25:d9bd:2aff
1772c19:dd:d9:dd:c25:c25:d9bd:2b00/1242c19:dd:d9:dd:c25:c25:d9bd:2b0f
1782c19:dd:d9:dd:c25:c25:d9bd:2b10/1242c19:dd:d9:dd:c25:c25:d9bd:2b1f
1792c19:dd:d9:dd:c25:c25:d9bd:2b20/1242c19:dd:d9:dd:c25:c25:d9bd:2b2f
1802c19:dd:d9:dd:c25:c25:d9bd:2b30/1242c19:dd:d9:dd:c25:c25:d9bd:2b3f
1812c19:dd:d9:dd:c25:c25:d9bd:2b40/1242c19:dd:d9:dd:c25:c25:d9bd:2b4f
1822c19:dd:d9:dd:c25:c25:d9bd:2b50/1242c19:dd:d9:dd:c25:c25:d9bd:2b5f
1832c19:dd:d9:dd:c25:c25:d9bd:2b60/1242c19:dd:d9:dd:c25:c25:d9bd:2b6f
1842c19:dd:d9:dd:c25:c25:d9bd:2b70/1242c19:dd:d9:dd:c25:c25:d9bd:2b7f
1852c19:dd:d9:dd:c25:c25:d9bd:2b80/1242c19:dd:d9:dd:c25:c25:d9bd:2b8f
1862c19:dd:d9:dd:c25:c25:d9bd:2b90/1242c19:dd:d9:dd:c25:c25:d9bd:2b9f
1872c19:dd:d9:dd:c25:c25:d9bd:2ba0/1242c19:dd:d9:dd:c25:c25:d9bd:2baf
1882c19:dd:d9:dd:c25:c25:d9bd:2bb0/1242c19:dd:d9:dd:c25:c25:d9bd:2bbf
1892c19:dd:d9:dd:c25:c25:d9bd:2bc0/1242c19:dd:d9:dd:c25:c25:d9bd:2bcf
1902c19:dd:d9:dd:c25:c25:d9bd:2bd0/1242c19:dd:d9:dd:c25:c25:d9bd:2bdf
1912c19:dd:d9:dd:c25:c25:d9bd:2be0/1242c19:dd:d9:dd:c25:c25:d9bd:2bef
1922c19:dd:d9:dd:c25:c25:d9bd:2bf0/1242c19:dd:d9:dd:c25:c25:d9bd:2bff
1932c19:dd:d9:dd:c25:c25:d9bd:2c00/1242c19:dd:d9:dd:c25:c25:d9bd:2c0f
1942c19:dd:d9:dd:c25:c25:d9bd:2c10/1242c19:dd:d9:dd:c25:c25:d9bd:2c1f
1952c19:dd:d9:dd:c25:c25:d9bd:2c20/1242c19:dd:d9:dd:c25:c25:d9bd:2c2f
1962c19:dd:d9:dd:c25:c25:d9bd:2c30/1242c19:dd:d9:dd:c25:c25:d9bd:2c3f
1972c19:dd:d9:dd:c25:c25:d9bd:2c40/1242c19:dd:d9:dd:c25:c25:d9bd:2c4f
1982c19:dd:d9:dd:c25:c25:d9bd:2c50/1242c19:dd:d9:dd:c25:c25:d9bd:2c5f
1992c19:dd:d9:dd:c25:c25:d9bd:2c60/1242c19:dd:d9:dd:c25:c25:d9bd:2c6f
2002c19:dd:d9:dd:c25:c25:d9bd:2c70/1242c19:dd:d9:dd:c25:c25:d9bd:2c7f
2012c19:dd:d9:dd:c25:c25:d9bd:2c80/1242c19:dd:d9:dd:c25:c25:d9bd:2c8f
2022c19:dd:d9:dd:c25:c25:d9bd:2c90/1242c19:dd:d9:dd:c25:c25:d9bd:2c9f
2032c19:dd:d9:dd:c25:c25:d9bd:2ca0/1242c19:dd:d9:dd:c25:c25:d9bd:2caf
2042c19:dd:d9:dd:c25:c25:d9bd:2cb0/1242c19:dd:d9:dd:c25:c25:d9bd:2cbf
2052c19:dd:d9:dd:c25:c25:d9bd:2cc0/1242c19:dd:d9:dd:c25:c25:d9bd:2ccf
2062c19:dd:d9:dd:c25:c25:d9bd:2cd0/1242c19:dd:d9:dd:c25:c25:d9bd:2cdf
2072c19:dd:d9:dd:c25:c25:d9bd:2ce0/1242c19:dd:d9:dd:c25:c25:d9bd:2cef
2082c19:dd:d9:dd:c25:c25:d9bd:2cf0/1242c19:dd:d9:dd:c25:c25:d9bd:2cff
2092c19:dd:d9:dd:c25:c25:d9bd:2d00/1242c19:dd:d9:dd:c25:c25:d9bd:2d0f
2102c19:dd:d9:dd:c25:c25:d9bd:2d10/1242c19:dd:d9:dd:c25:c25:d9bd:2d1f
2112c19:dd:d9:dd:c25:c25:d9bd:2d20/1242c19:dd:d9:dd:c25:c25:d9bd:2d2f
2122c19:dd:d9:dd:c25:c25:d9bd:2d30/1242c19:dd:d9:dd:c25:c25:d9bd:2d3f
2132c19:dd:d9:dd:c25:c25:d9bd:2d40/1242c19:dd:d9:dd:c25:c25:d9bd:2d4f
2142c19:dd:d9:dd:c25:c25:d9bd:2d50/1242c19:dd:d9:dd:c25:c25:d9bd:2d5f
2152c19:dd:d9:dd:c25:c25:d9bd:2d60/1242c19:dd:d9:dd:c25:c25:d9bd:2d6f
2162c19:dd:d9:dd:c25:c25:d9bd:2d70/1242c19:dd:d9:dd:c25:c25:d9bd:2d7f
2172c19:dd:d9:dd:c25:c25:d9bd:2d80/1242c19:dd:d9:dd:c25:c25:d9bd:2d8f
2182c19:dd:d9:dd:c25:c25:d9bd:2d90/1242c19:dd:d9:dd:c25:c25:d9bd:2d9f
2192c19:dd:d9:dd:c25:c25:d9bd:2da0/1242c19:dd:d9:dd:c25:c25:d9bd:2daf
2202c19:dd:d9:dd:c25:c25:d9bd:2db0/1242c19:dd:d9:dd:c25:c25:d9bd:2dbf
2212c19:dd:d9:dd:c25:c25:d9bd:2dc0/1242c19:dd:d9:dd:c25:c25:d9bd:2dcf
2222c19:dd:d9:dd:c25:c25:d9bd:2dd0/1242c19:dd:d9:dd:c25:c25:d9bd:2ddf
2232c19:dd:d9:dd:c25:c25:d9bd:2de0/1242c19:dd:d9:dd:c25:c25:d9bd:2def
2242c19:dd:d9:dd:c25:c25:d9bd:2df0/1242c19:dd:d9:dd:c25:c25:d9bd:2dff
2252c19:dd:d9:dd:c25:c25:d9bd:2e00/1242c19:dd:d9:dd:c25:c25:d9bd:2e0f
2262c19:dd:d9:dd:c25:c25:d9bd:2e10/1242c19:dd:d9:dd:c25:c25:d9bd:2e1f
2272c19:dd:d9:dd:c25:c25:d9bd:2e20/1242c19:dd:d9:dd:c25:c25:d9bd:2e2f
2282c19:dd:d9:dd:c25:c25:d9bd:2e30/1242c19:dd:d9:dd:c25:c25:d9bd:2e3f
2292c19:dd:d9:dd:c25:c25:d9bd:2e40/1242c19:dd:d9:dd:c25:c25:d9bd:2e4f
2302c19:dd:d9:dd:c25:c25:d9bd:2e50/1242c19:dd:d9:dd:c25:c25:d9bd:2e5f
2312c19:dd:d9:dd:c25:c25:d9bd:2e60/1242c19:dd:d9:dd:c25:c25:d9bd:2e6f
2322c19:dd:d9:dd:c25:c25:d9bd:2e70/1242c19:dd:d9:dd:c25:c25:d9bd:2e7f
2332c19:dd:d9:dd:c25:c25:d9bd:2e80/1242c19:dd:d9:dd:c25:c25:d9bd:2e8f
2342c19:dd:d9:dd:c25:c25:d9bd:2e90/1242c19:dd:d9:dd:c25:c25:d9bd:2e9f
2352c19:dd:d9:dd:c25:c25:d9bd:2ea0/1242c19:dd:d9:dd:c25:c25:d9bd:2eaf
2362c19:dd:d9:dd:c25:c25:d9bd:2eb0/1242c19:dd:d9:dd:c25:c25:d9bd:2ebf
2372c19:dd:d9:dd:c25:c25:d9bd:2ec0/1242c19:dd:d9:dd:c25:c25:d9bd:2ecf
2382c19:dd:d9:dd:c25:c25:d9bd:2ed0/1242c19:dd:d9:dd:c25:c25:d9bd:2edf
2392c19:dd:d9:dd:c25:c25:d9bd:2ee0/1242c19:dd:d9:dd:c25:c25:d9bd:2eef
2402c19:dd:d9:dd:c25:c25:d9bd:2ef0/1242c19:dd:d9:dd:c25:c25:d9bd:2eff
2412c19:dd:d9:dd:c25:c25:d9bd:2f00/1242c19:dd:d9:dd:c25:c25:d9bd:2f0f
2422c19:dd:d9:dd:c25:c25:d9bd:2f10/1242c19:dd:d9:dd:c25:c25:d9bd:2f1f
2432c19:dd:d9:dd:c25:c25:d9bd:2f20/1242c19:dd:d9:dd:c25:c25:d9bd:2f2f
2442c19:dd:d9:dd:c25:c25:d9bd:2f30/1242c19:dd:d9:dd:c25:c25:d9bd:2f3f
2452c19:dd:d9:dd:c25:c25:d9bd:2f40/1242c19:dd:d9:dd:c25:c25:d9bd:2f4f
2462c19:dd:d9:dd:c25:c25:d9bd:2f50/1242c19:dd:d9:dd:c25:c25:d9bd:2f5f
2472c19:dd:d9:dd:c25:c25:d9bd:2f60/1242c19:dd:d9:dd:c25:c25:d9bd:2f6f
2482c19:dd:d9:dd:c25:c25:d9bd:2f70/1242c19:dd:d9:dd:c25:c25:d9bd:2f7f
2492c19:dd:d9:dd:c25:c25:d9bd:2f80/1242c19:dd:d9:dd:c25:c25:d9bd:2f8f
2502c19:dd:d9:dd:c25:c25:d9bd:2f90/1242c19:dd:d9:dd:c25:c25:d9bd:2f9f
2512c19:dd:d9:dd:c25:c25:d9bd:2fa0/1242c19:dd:d9:dd:c25:c25:d9bd:2faf
2522c19:dd:d9:dd:c25:c25:d9bd:2fb0/1242c19:dd:d9:dd:c25:c25:d9bd:2fbf
2532c19:dd:d9:dd:c25:c25:d9bd:2fc0/1242c19:dd:d9:dd:c25:c25:d9bd:2fcf
2542c19:dd:d9:dd:c25:c25:d9bd:2fd0/1242c19:dd:d9:dd:c25:c25:d9bd:2fdf
2552c19:dd:d9:dd:c25:c25:d9bd:2fe0/1242c19:dd:d9:dd:c25:c25:d9bd:2fef
2562c19:dd:d9:dd:c25:c25:d9bd:2ff0/1242c19:dd:d9:dd:c25:c25:d9bd:2fff

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.