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:dd2c:3000/116
First address
2c19:dd:d9:dd:c25:c25:dd2c:3000
Last address
2c19:dd:d9:dd:c25:c25:dd2c:3fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:dd2c:3000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
3.c.2.d.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:dd2c:3000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:dd2c:3000/1242c19:dd:d9:dd:c25:c25:dd2c:300f
22c19:dd:d9:dd:c25:c25:dd2c:3010/1242c19:dd:d9:dd:c25:c25:dd2c:301f
32c19:dd:d9:dd:c25:c25:dd2c:3020/1242c19:dd:d9:dd:c25:c25:dd2c:302f
42c19:dd:d9:dd:c25:c25:dd2c:3030/1242c19:dd:d9:dd:c25:c25:dd2c:303f
52c19:dd:d9:dd:c25:c25:dd2c:3040/1242c19:dd:d9:dd:c25:c25:dd2c:304f
62c19:dd:d9:dd:c25:c25:dd2c:3050/1242c19:dd:d9:dd:c25:c25:dd2c:305f
72c19:dd:d9:dd:c25:c25:dd2c:3060/1242c19:dd:d9:dd:c25:c25:dd2c:306f
82c19:dd:d9:dd:c25:c25:dd2c:3070/1242c19:dd:d9:dd:c25:c25:dd2c:307f
92c19:dd:d9:dd:c25:c25:dd2c:3080/1242c19:dd:d9:dd:c25:c25:dd2c:308f
102c19:dd:d9:dd:c25:c25:dd2c:3090/1242c19:dd:d9:dd:c25:c25:dd2c:309f
112c19:dd:d9:dd:c25:c25:dd2c:30a0/1242c19:dd:d9:dd:c25:c25:dd2c:30af
122c19:dd:d9:dd:c25:c25:dd2c:30b0/1242c19:dd:d9:dd:c25:c25:dd2c:30bf
132c19:dd:d9:dd:c25:c25:dd2c:30c0/1242c19:dd:d9:dd:c25:c25:dd2c:30cf
142c19:dd:d9:dd:c25:c25:dd2c:30d0/1242c19:dd:d9:dd:c25:c25:dd2c:30df
152c19:dd:d9:dd:c25:c25:dd2c:30e0/1242c19:dd:d9:dd:c25:c25:dd2c:30ef
162c19:dd:d9:dd:c25:c25:dd2c:30f0/1242c19:dd:d9:dd:c25:c25:dd2c:30ff
172c19:dd:d9:dd:c25:c25:dd2c:3100/1242c19:dd:d9:dd:c25:c25:dd2c:310f
182c19:dd:d9:dd:c25:c25:dd2c:3110/1242c19:dd:d9:dd:c25:c25:dd2c:311f
192c19:dd:d9:dd:c25:c25:dd2c:3120/1242c19:dd:d9:dd:c25:c25:dd2c:312f
202c19:dd:d9:dd:c25:c25:dd2c:3130/1242c19:dd:d9:dd:c25:c25:dd2c:313f
212c19:dd:d9:dd:c25:c25:dd2c:3140/1242c19:dd:d9:dd:c25:c25:dd2c:314f
222c19:dd:d9:dd:c25:c25:dd2c:3150/1242c19:dd:d9:dd:c25:c25:dd2c:315f
232c19:dd:d9:dd:c25:c25:dd2c:3160/1242c19:dd:d9:dd:c25:c25:dd2c:316f
242c19:dd:d9:dd:c25:c25:dd2c:3170/1242c19:dd:d9:dd:c25:c25:dd2c:317f
252c19:dd:d9:dd:c25:c25:dd2c:3180/1242c19:dd:d9:dd:c25:c25:dd2c:318f
262c19:dd:d9:dd:c25:c25:dd2c:3190/1242c19:dd:d9:dd:c25:c25:dd2c:319f
272c19:dd:d9:dd:c25:c25:dd2c:31a0/1242c19:dd:d9:dd:c25:c25:dd2c:31af
282c19:dd:d9:dd:c25:c25:dd2c:31b0/1242c19:dd:d9:dd:c25:c25:dd2c:31bf
292c19:dd:d9:dd:c25:c25:dd2c:31c0/1242c19:dd:d9:dd:c25:c25:dd2c:31cf
302c19:dd:d9:dd:c25:c25:dd2c:31d0/1242c19:dd:d9:dd:c25:c25:dd2c:31df
312c19:dd:d9:dd:c25:c25:dd2c:31e0/1242c19:dd:d9:dd:c25:c25:dd2c:31ef
322c19:dd:d9:dd:c25:c25:dd2c:31f0/1242c19:dd:d9:dd:c25:c25:dd2c:31ff
332c19:dd:d9:dd:c25:c25:dd2c:3200/1242c19:dd:d9:dd:c25:c25:dd2c:320f
342c19:dd:d9:dd:c25:c25:dd2c:3210/1242c19:dd:d9:dd:c25:c25:dd2c:321f
352c19:dd:d9:dd:c25:c25:dd2c:3220/1242c19:dd:d9:dd:c25:c25:dd2c:322f
362c19:dd:d9:dd:c25:c25:dd2c:3230/1242c19:dd:d9:dd:c25:c25:dd2c:323f
372c19:dd:d9:dd:c25:c25:dd2c:3240/1242c19:dd:d9:dd:c25:c25:dd2c:324f
382c19:dd:d9:dd:c25:c25:dd2c:3250/1242c19:dd:d9:dd:c25:c25:dd2c:325f
392c19:dd:d9:dd:c25:c25:dd2c:3260/1242c19:dd:d9:dd:c25:c25:dd2c:326f
402c19:dd:d9:dd:c25:c25:dd2c:3270/1242c19:dd:d9:dd:c25:c25:dd2c:327f
412c19:dd:d9:dd:c25:c25:dd2c:3280/1242c19:dd:d9:dd:c25:c25:dd2c:328f
422c19:dd:d9:dd:c25:c25:dd2c:3290/1242c19:dd:d9:dd:c25:c25:dd2c:329f
432c19:dd:d9:dd:c25:c25:dd2c:32a0/1242c19:dd:d9:dd:c25:c25:dd2c:32af
442c19:dd:d9:dd:c25:c25:dd2c:32b0/1242c19:dd:d9:dd:c25:c25:dd2c:32bf
452c19:dd:d9:dd:c25:c25:dd2c:32c0/1242c19:dd:d9:dd:c25:c25:dd2c:32cf
462c19:dd:d9:dd:c25:c25:dd2c:32d0/1242c19:dd:d9:dd:c25:c25:dd2c:32df
472c19:dd:d9:dd:c25:c25:dd2c:32e0/1242c19:dd:d9:dd:c25:c25:dd2c:32ef
482c19:dd:d9:dd:c25:c25:dd2c:32f0/1242c19:dd:d9:dd:c25:c25:dd2c:32ff
492c19:dd:d9:dd:c25:c25:dd2c:3300/1242c19:dd:d9:dd:c25:c25:dd2c:330f
502c19:dd:d9:dd:c25:c25:dd2c:3310/1242c19:dd:d9:dd:c25:c25:dd2c:331f
512c19:dd:d9:dd:c25:c25:dd2c:3320/1242c19:dd:d9:dd:c25:c25:dd2c:332f
522c19:dd:d9:dd:c25:c25:dd2c:3330/1242c19:dd:d9:dd:c25:c25:dd2c:333f
532c19:dd:d9:dd:c25:c25:dd2c:3340/1242c19:dd:d9:dd:c25:c25:dd2c:334f
542c19:dd:d9:dd:c25:c25:dd2c:3350/1242c19:dd:d9:dd:c25:c25:dd2c:335f
552c19:dd:d9:dd:c25:c25:dd2c:3360/1242c19:dd:d9:dd:c25:c25:dd2c:336f
562c19:dd:d9:dd:c25:c25:dd2c:3370/1242c19:dd:d9:dd:c25:c25:dd2c:337f
572c19:dd:d9:dd:c25:c25:dd2c:3380/1242c19:dd:d9:dd:c25:c25:dd2c:338f
582c19:dd:d9:dd:c25:c25:dd2c:3390/1242c19:dd:d9:dd:c25:c25:dd2c:339f
592c19:dd:d9:dd:c25:c25:dd2c:33a0/1242c19:dd:d9:dd:c25:c25:dd2c:33af
602c19:dd:d9:dd:c25:c25:dd2c:33b0/1242c19:dd:d9:dd:c25:c25:dd2c:33bf
612c19:dd:d9:dd:c25:c25:dd2c:33c0/1242c19:dd:d9:dd:c25:c25:dd2c:33cf
622c19:dd:d9:dd:c25:c25:dd2c:33d0/1242c19:dd:d9:dd:c25:c25:dd2c:33df
632c19:dd:d9:dd:c25:c25:dd2c:33e0/1242c19:dd:d9:dd:c25:c25:dd2c:33ef
642c19:dd:d9:dd:c25:c25:dd2c:33f0/1242c19:dd:d9:dd:c25:c25:dd2c:33ff
652c19:dd:d9:dd:c25:c25:dd2c:3400/1242c19:dd:d9:dd:c25:c25:dd2c:340f
662c19:dd:d9:dd:c25:c25:dd2c:3410/1242c19:dd:d9:dd:c25:c25:dd2c:341f
672c19:dd:d9:dd:c25:c25:dd2c:3420/1242c19:dd:d9:dd:c25:c25:dd2c:342f
682c19:dd:d9:dd:c25:c25:dd2c:3430/1242c19:dd:d9:dd:c25:c25:dd2c:343f
692c19:dd:d9:dd:c25:c25:dd2c:3440/1242c19:dd:d9:dd:c25:c25:dd2c:344f
702c19:dd:d9:dd:c25:c25:dd2c:3450/1242c19:dd:d9:dd:c25:c25:dd2c:345f
712c19:dd:d9:dd:c25:c25:dd2c:3460/1242c19:dd:d9:dd:c25:c25:dd2c:346f
722c19:dd:d9:dd:c25:c25:dd2c:3470/1242c19:dd:d9:dd:c25:c25:dd2c:347f
732c19:dd:d9:dd:c25:c25:dd2c:3480/1242c19:dd:d9:dd:c25:c25:dd2c:348f
742c19:dd:d9:dd:c25:c25:dd2c:3490/1242c19:dd:d9:dd:c25:c25:dd2c:349f
752c19:dd:d9:dd:c25:c25:dd2c:34a0/1242c19:dd:d9:dd:c25:c25:dd2c:34af
762c19:dd:d9:dd:c25:c25:dd2c:34b0/1242c19:dd:d9:dd:c25:c25:dd2c:34bf
772c19:dd:d9:dd:c25:c25:dd2c:34c0/1242c19:dd:d9:dd:c25:c25:dd2c:34cf
782c19:dd:d9:dd:c25:c25:dd2c:34d0/1242c19:dd:d9:dd:c25:c25:dd2c:34df
792c19:dd:d9:dd:c25:c25:dd2c:34e0/1242c19:dd:d9:dd:c25:c25:dd2c:34ef
802c19:dd:d9:dd:c25:c25:dd2c:34f0/1242c19:dd:d9:dd:c25:c25:dd2c:34ff
812c19:dd:d9:dd:c25:c25:dd2c:3500/1242c19:dd:d9:dd:c25:c25:dd2c:350f
822c19:dd:d9:dd:c25:c25:dd2c:3510/1242c19:dd:d9:dd:c25:c25:dd2c:351f
832c19:dd:d9:dd:c25:c25:dd2c:3520/1242c19:dd:d9:dd:c25:c25:dd2c:352f
842c19:dd:d9:dd:c25:c25:dd2c:3530/1242c19:dd:d9:dd:c25:c25:dd2c:353f
852c19:dd:d9:dd:c25:c25:dd2c:3540/1242c19:dd:d9:dd:c25:c25:dd2c:354f
862c19:dd:d9:dd:c25:c25:dd2c:3550/1242c19:dd:d9:dd:c25:c25:dd2c:355f
872c19:dd:d9:dd:c25:c25:dd2c:3560/1242c19:dd:d9:dd:c25:c25:dd2c:356f
882c19:dd:d9:dd:c25:c25:dd2c:3570/1242c19:dd:d9:dd:c25:c25:dd2c:357f
892c19:dd:d9:dd:c25:c25:dd2c:3580/1242c19:dd:d9:dd:c25:c25:dd2c:358f
902c19:dd:d9:dd:c25:c25:dd2c:3590/1242c19:dd:d9:dd:c25:c25:dd2c:359f
912c19:dd:d9:dd:c25:c25:dd2c:35a0/1242c19:dd:d9:dd:c25:c25:dd2c:35af
922c19:dd:d9:dd:c25:c25:dd2c:35b0/1242c19:dd:d9:dd:c25:c25:dd2c:35bf
932c19:dd:d9:dd:c25:c25:dd2c:35c0/1242c19:dd:d9:dd:c25:c25:dd2c:35cf
942c19:dd:d9:dd:c25:c25:dd2c:35d0/1242c19:dd:d9:dd:c25:c25:dd2c:35df
952c19:dd:d9:dd:c25:c25:dd2c:35e0/1242c19:dd:d9:dd:c25:c25:dd2c:35ef
962c19:dd:d9:dd:c25:c25:dd2c:35f0/1242c19:dd:d9:dd:c25:c25:dd2c:35ff
972c19:dd:d9:dd:c25:c25:dd2c:3600/1242c19:dd:d9:dd:c25:c25:dd2c:360f
982c19:dd:d9:dd:c25:c25:dd2c:3610/1242c19:dd:d9:dd:c25:c25:dd2c:361f
992c19:dd:d9:dd:c25:c25:dd2c:3620/1242c19:dd:d9:dd:c25:c25:dd2c:362f
1002c19:dd:d9:dd:c25:c25:dd2c:3630/1242c19:dd:d9:dd:c25:c25:dd2c:363f
1012c19:dd:d9:dd:c25:c25:dd2c:3640/1242c19:dd:d9:dd:c25:c25:dd2c:364f
1022c19:dd:d9:dd:c25:c25:dd2c:3650/1242c19:dd:d9:dd:c25:c25:dd2c:365f
1032c19:dd:d9:dd:c25:c25:dd2c:3660/1242c19:dd:d9:dd:c25:c25:dd2c:366f
1042c19:dd:d9:dd:c25:c25:dd2c:3670/1242c19:dd:d9:dd:c25:c25:dd2c:367f
1052c19:dd:d9:dd:c25:c25:dd2c:3680/1242c19:dd:d9:dd:c25:c25:dd2c:368f
1062c19:dd:d9:dd:c25:c25:dd2c:3690/1242c19:dd:d9:dd:c25:c25:dd2c:369f
1072c19:dd:d9:dd:c25:c25:dd2c:36a0/1242c19:dd:d9:dd:c25:c25:dd2c:36af
1082c19:dd:d9:dd:c25:c25:dd2c:36b0/1242c19:dd:d9:dd:c25:c25:dd2c:36bf
1092c19:dd:d9:dd:c25:c25:dd2c:36c0/1242c19:dd:d9:dd:c25:c25:dd2c:36cf
1102c19:dd:d9:dd:c25:c25:dd2c:36d0/1242c19:dd:d9:dd:c25:c25:dd2c:36df
1112c19:dd:d9:dd:c25:c25:dd2c:36e0/1242c19:dd:d9:dd:c25:c25:dd2c:36ef
1122c19:dd:d9:dd:c25:c25:dd2c:36f0/1242c19:dd:d9:dd:c25:c25:dd2c:36ff
1132c19:dd:d9:dd:c25:c25:dd2c:3700/1242c19:dd:d9:dd:c25:c25:dd2c:370f
1142c19:dd:d9:dd:c25:c25:dd2c:3710/1242c19:dd:d9:dd:c25:c25:dd2c:371f
1152c19:dd:d9:dd:c25:c25:dd2c:3720/1242c19:dd:d9:dd:c25:c25:dd2c:372f
1162c19:dd:d9:dd:c25:c25:dd2c:3730/1242c19:dd:d9:dd:c25:c25:dd2c:373f
1172c19:dd:d9:dd:c25:c25:dd2c:3740/1242c19:dd:d9:dd:c25:c25:dd2c:374f
1182c19:dd:d9:dd:c25:c25:dd2c:3750/1242c19:dd:d9:dd:c25:c25:dd2c:375f
1192c19:dd:d9:dd:c25:c25:dd2c:3760/1242c19:dd:d9:dd:c25:c25:dd2c:376f
1202c19:dd:d9:dd:c25:c25:dd2c:3770/1242c19:dd:d9:dd:c25:c25:dd2c:377f
1212c19:dd:d9:dd:c25:c25:dd2c:3780/1242c19:dd:d9:dd:c25:c25:dd2c:378f
1222c19:dd:d9:dd:c25:c25:dd2c:3790/1242c19:dd:d9:dd:c25:c25:dd2c:379f
1232c19:dd:d9:dd:c25:c25:dd2c:37a0/1242c19:dd:d9:dd:c25:c25:dd2c:37af
1242c19:dd:d9:dd:c25:c25:dd2c:37b0/1242c19:dd:d9:dd:c25:c25:dd2c:37bf
1252c19:dd:d9:dd:c25:c25:dd2c:37c0/1242c19:dd:d9:dd:c25:c25:dd2c:37cf
1262c19:dd:d9:dd:c25:c25:dd2c:37d0/1242c19:dd:d9:dd:c25:c25:dd2c:37df
1272c19:dd:d9:dd:c25:c25:dd2c:37e0/1242c19:dd:d9:dd:c25:c25:dd2c:37ef
1282c19:dd:d9:dd:c25:c25:dd2c:37f0/1242c19:dd:d9:dd:c25:c25:dd2c:37ff
1292c19:dd:d9:dd:c25:c25:dd2c:3800/1242c19:dd:d9:dd:c25:c25:dd2c:380f
1302c19:dd:d9:dd:c25:c25:dd2c:3810/1242c19:dd:d9:dd:c25:c25:dd2c:381f
1312c19:dd:d9:dd:c25:c25:dd2c:3820/1242c19:dd:d9:dd:c25:c25:dd2c:382f
1322c19:dd:d9:dd:c25:c25:dd2c:3830/1242c19:dd:d9:dd:c25:c25:dd2c:383f
1332c19:dd:d9:dd:c25:c25:dd2c:3840/1242c19:dd:d9:dd:c25:c25:dd2c:384f
1342c19:dd:d9:dd:c25:c25:dd2c:3850/1242c19:dd:d9:dd:c25:c25:dd2c:385f
1352c19:dd:d9:dd:c25:c25:dd2c:3860/1242c19:dd:d9:dd:c25:c25:dd2c:386f
1362c19:dd:d9:dd:c25:c25:dd2c:3870/1242c19:dd:d9:dd:c25:c25:dd2c:387f
1372c19:dd:d9:dd:c25:c25:dd2c:3880/1242c19:dd:d9:dd:c25:c25:dd2c:388f
1382c19:dd:d9:dd:c25:c25:dd2c:3890/1242c19:dd:d9:dd:c25:c25:dd2c:389f
1392c19:dd:d9:dd:c25:c25:dd2c:38a0/1242c19:dd:d9:dd:c25:c25:dd2c:38af
1402c19:dd:d9:dd:c25:c25:dd2c:38b0/1242c19:dd:d9:dd:c25:c25:dd2c:38bf
1412c19:dd:d9:dd:c25:c25:dd2c:38c0/1242c19:dd:d9:dd:c25:c25:dd2c:38cf
1422c19:dd:d9:dd:c25:c25:dd2c:38d0/1242c19:dd:d9:dd:c25:c25:dd2c:38df
1432c19:dd:d9:dd:c25:c25:dd2c:38e0/1242c19:dd:d9:dd:c25:c25:dd2c:38ef
1442c19:dd:d9:dd:c25:c25:dd2c:38f0/1242c19:dd:d9:dd:c25:c25:dd2c:38ff
1452c19:dd:d9:dd:c25:c25:dd2c:3900/1242c19:dd:d9:dd:c25:c25:dd2c:390f
1462c19:dd:d9:dd:c25:c25:dd2c:3910/1242c19:dd:d9:dd:c25:c25:dd2c:391f
1472c19:dd:d9:dd:c25:c25:dd2c:3920/1242c19:dd:d9:dd:c25:c25:dd2c:392f
1482c19:dd:d9:dd:c25:c25:dd2c:3930/1242c19:dd:d9:dd:c25:c25:dd2c:393f
1492c19:dd:d9:dd:c25:c25:dd2c:3940/1242c19:dd:d9:dd:c25:c25:dd2c:394f
1502c19:dd:d9:dd:c25:c25:dd2c:3950/1242c19:dd:d9:dd:c25:c25:dd2c:395f
1512c19:dd:d9:dd:c25:c25:dd2c:3960/1242c19:dd:d9:dd:c25:c25:dd2c:396f
1522c19:dd:d9:dd:c25:c25:dd2c:3970/1242c19:dd:d9:dd:c25:c25:dd2c:397f
1532c19:dd:d9:dd:c25:c25:dd2c:3980/1242c19:dd:d9:dd:c25:c25:dd2c:398f
1542c19:dd:d9:dd:c25:c25:dd2c:3990/1242c19:dd:d9:dd:c25:c25:dd2c:399f
1552c19:dd:d9:dd:c25:c25:dd2c:39a0/1242c19:dd:d9:dd:c25:c25:dd2c:39af
1562c19:dd:d9:dd:c25:c25:dd2c:39b0/1242c19:dd:d9:dd:c25:c25:dd2c:39bf
1572c19:dd:d9:dd:c25:c25:dd2c:39c0/1242c19:dd:d9:dd:c25:c25:dd2c:39cf
1582c19:dd:d9:dd:c25:c25:dd2c:39d0/1242c19:dd:d9:dd:c25:c25:dd2c:39df
1592c19:dd:d9:dd:c25:c25:dd2c:39e0/1242c19:dd:d9:dd:c25:c25:dd2c:39ef
1602c19:dd:d9:dd:c25:c25:dd2c:39f0/1242c19:dd:d9:dd:c25:c25:dd2c:39ff
1612c19:dd:d9:dd:c25:c25:dd2c:3a00/1242c19:dd:d9:dd:c25:c25:dd2c:3a0f
1622c19:dd:d9:dd:c25:c25:dd2c:3a10/1242c19:dd:d9:dd:c25:c25:dd2c:3a1f
1632c19:dd:d9:dd:c25:c25:dd2c:3a20/1242c19:dd:d9:dd:c25:c25:dd2c:3a2f
1642c19:dd:d9:dd:c25:c25:dd2c:3a30/1242c19:dd:d9:dd:c25:c25:dd2c:3a3f
1652c19:dd:d9:dd:c25:c25:dd2c:3a40/1242c19:dd:d9:dd:c25:c25:dd2c:3a4f
1662c19:dd:d9:dd:c25:c25:dd2c:3a50/1242c19:dd:d9:dd:c25:c25:dd2c:3a5f
1672c19:dd:d9:dd:c25:c25:dd2c:3a60/1242c19:dd:d9:dd:c25:c25:dd2c:3a6f
1682c19:dd:d9:dd:c25:c25:dd2c:3a70/1242c19:dd:d9:dd:c25:c25:dd2c:3a7f
1692c19:dd:d9:dd:c25:c25:dd2c:3a80/1242c19:dd:d9:dd:c25:c25:dd2c:3a8f
1702c19:dd:d9:dd:c25:c25:dd2c:3a90/1242c19:dd:d9:dd:c25:c25:dd2c:3a9f
1712c19:dd:d9:dd:c25:c25:dd2c:3aa0/1242c19:dd:d9:dd:c25:c25:dd2c:3aaf
1722c19:dd:d9:dd:c25:c25:dd2c:3ab0/1242c19:dd:d9:dd:c25:c25:dd2c:3abf
1732c19:dd:d9:dd:c25:c25:dd2c:3ac0/1242c19:dd:d9:dd:c25:c25:dd2c:3acf
1742c19:dd:d9:dd:c25:c25:dd2c:3ad0/1242c19:dd:d9:dd:c25:c25:dd2c:3adf
1752c19:dd:d9:dd:c25:c25:dd2c:3ae0/1242c19:dd:d9:dd:c25:c25:dd2c:3aef
1762c19:dd:d9:dd:c25:c25:dd2c:3af0/1242c19:dd:d9:dd:c25:c25:dd2c:3aff
1772c19:dd:d9:dd:c25:c25:dd2c:3b00/1242c19:dd:d9:dd:c25:c25:dd2c:3b0f
1782c19:dd:d9:dd:c25:c25:dd2c:3b10/1242c19:dd:d9:dd:c25:c25:dd2c:3b1f
1792c19:dd:d9:dd:c25:c25:dd2c:3b20/1242c19:dd:d9:dd:c25:c25:dd2c:3b2f
1802c19:dd:d9:dd:c25:c25:dd2c:3b30/1242c19:dd:d9:dd:c25:c25:dd2c:3b3f
1812c19:dd:d9:dd:c25:c25:dd2c:3b40/1242c19:dd:d9:dd:c25:c25:dd2c:3b4f
1822c19:dd:d9:dd:c25:c25:dd2c:3b50/1242c19:dd:d9:dd:c25:c25:dd2c:3b5f
1832c19:dd:d9:dd:c25:c25:dd2c:3b60/1242c19:dd:d9:dd:c25:c25:dd2c:3b6f
1842c19:dd:d9:dd:c25:c25:dd2c:3b70/1242c19:dd:d9:dd:c25:c25:dd2c:3b7f
1852c19:dd:d9:dd:c25:c25:dd2c:3b80/1242c19:dd:d9:dd:c25:c25:dd2c:3b8f
1862c19:dd:d9:dd:c25:c25:dd2c:3b90/1242c19:dd:d9:dd:c25:c25:dd2c:3b9f
1872c19:dd:d9:dd:c25:c25:dd2c:3ba0/1242c19:dd:d9:dd:c25:c25:dd2c:3baf
1882c19:dd:d9:dd:c25:c25:dd2c:3bb0/1242c19:dd:d9:dd:c25:c25:dd2c:3bbf
1892c19:dd:d9:dd:c25:c25:dd2c:3bc0/1242c19:dd:d9:dd:c25:c25:dd2c:3bcf
1902c19:dd:d9:dd:c25:c25:dd2c:3bd0/1242c19:dd:d9:dd:c25:c25:dd2c:3bdf
1912c19:dd:d9:dd:c25:c25:dd2c:3be0/1242c19:dd:d9:dd:c25:c25:dd2c:3bef
1922c19:dd:d9:dd:c25:c25:dd2c:3bf0/1242c19:dd:d9:dd:c25:c25:dd2c:3bff
1932c19:dd:d9:dd:c25:c25:dd2c:3c00/1242c19:dd:d9:dd:c25:c25:dd2c:3c0f
1942c19:dd:d9:dd:c25:c25:dd2c:3c10/1242c19:dd:d9:dd:c25:c25:dd2c:3c1f
1952c19:dd:d9:dd:c25:c25:dd2c:3c20/1242c19:dd:d9:dd:c25:c25:dd2c:3c2f
1962c19:dd:d9:dd:c25:c25:dd2c:3c30/1242c19:dd:d9:dd:c25:c25:dd2c:3c3f
1972c19:dd:d9:dd:c25:c25:dd2c:3c40/1242c19:dd:d9:dd:c25:c25:dd2c:3c4f
1982c19:dd:d9:dd:c25:c25:dd2c:3c50/1242c19:dd:d9:dd:c25:c25:dd2c:3c5f
1992c19:dd:d9:dd:c25:c25:dd2c:3c60/1242c19:dd:d9:dd:c25:c25:dd2c:3c6f
2002c19:dd:d9:dd:c25:c25:dd2c:3c70/1242c19:dd:d9:dd:c25:c25:dd2c:3c7f
2012c19:dd:d9:dd:c25:c25:dd2c:3c80/1242c19:dd:d9:dd:c25:c25:dd2c:3c8f
2022c19:dd:d9:dd:c25:c25:dd2c:3c90/1242c19:dd:d9:dd:c25:c25:dd2c:3c9f
2032c19:dd:d9:dd:c25:c25:dd2c:3ca0/1242c19:dd:d9:dd:c25:c25:dd2c:3caf
2042c19:dd:d9:dd:c25:c25:dd2c:3cb0/1242c19:dd:d9:dd:c25:c25:dd2c:3cbf
2052c19:dd:d9:dd:c25:c25:dd2c:3cc0/1242c19:dd:d9:dd:c25:c25:dd2c:3ccf
2062c19:dd:d9:dd:c25:c25:dd2c:3cd0/1242c19:dd:d9:dd:c25:c25:dd2c:3cdf
2072c19:dd:d9:dd:c25:c25:dd2c:3ce0/1242c19:dd:d9:dd:c25:c25:dd2c:3cef
2082c19:dd:d9:dd:c25:c25:dd2c:3cf0/1242c19:dd:d9:dd:c25:c25:dd2c:3cff
2092c19:dd:d9:dd:c25:c25:dd2c:3d00/1242c19:dd:d9:dd:c25:c25:dd2c:3d0f
2102c19:dd:d9:dd:c25:c25:dd2c:3d10/1242c19:dd:d9:dd:c25:c25:dd2c:3d1f
2112c19:dd:d9:dd:c25:c25:dd2c:3d20/1242c19:dd:d9:dd:c25:c25:dd2c:3d2f
2122c19:dd:d9:dd:c25:c25:dd2c:3d30/1242c19:dd:d9:dd:c25:c25:dd2c:3d3f
2132c19:dd:d9:dd:c25:c25:dd2c:3d40/1242c19:dd:d9:dd:c25:c25:dd2c:3d4f
2142c19:dd:d9:dd:c25:c25:dd2c:3d50/1242c19:dd:d9:dd:c25:c25:dd2c:3d5f
2152c19:dd:d9:dd:c25:c25:dd2c:3d60/1242c19:dd:d9:dd:c25:c25:dd2c:3d6f
2162c19:dd:d9:dd:c25:c25:dd2c:3d70/1242c19:dd:d9:dd:c25:c25:dd2c:3d7f
2172c19:dd:d9:dd:c25:c25:dd2c:3d80/1242c19:dd:d9:dd:c25:c25:dd2c:3d8f
2182c19:dd:d9:dd:c25:c25:dd2c:3d90/1242c19:dd:d9:dd:c25:c25:dd2c:3d9f
2192c19:dd:d9:dd:c25:c25:dd2c:3da0/1242c19:dd:d9:dd:c25:c25:dd2c:3daf
2202c19:dd:d9:dd:c25:c25:dd2c:3db0/1242c19:dd:d9:dd:c25:c25:dd2c:3dbf
2212c19:dd:d9:dd:c25:c25:dd2c:3dc0/1242c19:dd:d9:dd:c25:c25:dd2c:3dcf
2222c19:dd:d9:dd:c25:c25:dd2c:3dd0/1242c19:dd:d9:dd:c25:c25:dd2c:3ddf
2232c19:dd:d9:dd:c25:c25:dd2c:3de0/1242c19:dd:d9:dd:c25:c25:dd2c:3def
2242c19:dd:d9:dd:c25:c25:dd2c:3df0/1242c19:dd:d9:dd:c25:c25:dd2c:3dff
2252c19:dd:d9:dd:c25:c25:dd2c:3e00/1242c19:dd:d9:dd:c25:c25:dd2c:3e0f
2262c19:dd:d9:dd:c25:c25:dd2c:3e10/1242c19:dd:d9:dd:c25:c25:dd2c:3e1f
2272c19:dd:d9:dd:c25:c25:dd2c:3e20/1242c19:dd:d9:dd:c25:c25:dd2c:3e2f
2282c19:dd:d9:dd:c25:c25:dd2c:3e30/1242c19:dd:d9:dd:c25:c25:dd2c:3e3f
2292c19:dd:d9:dd:c25:c25:dd2c:3e40/1242c19:dd:d9:dd:c25:c25:dd2c:3e4f
2302c19:dd:d9:dd:c25:c25:dd2c:3e50/1242c19:dd:d9:dd:c25:c25:dd2c:3e5f
2312c19:dd:d9:dd:c25:c25:dd2c:3e60/1242c19:dd:d9:dd:c25:c25:dd2c:3e6f
2322c19:dd:d9:dd:c25:c25:dd2c:3e70/1242c19:dd:d9:dd:c25:c25:dd2c:3e7f
2332c19:dd:d9:dd:c25:c25:dd2c:3e80/1242c19:dd:d9:dd:c25:c25:dd2c:3e8f
2342c19:dd:d9:dd:c25:c25:dd2c:3e90/1242c19:dd:d9:dd:c25:c25:dd2c:3e9f
2352c19:dd:d9:dd:c25:c25:dd2c:3ea0/1242c19:dd:d9:dd:c25:c25:dd2c:3eaf
2362c19:dd:d9:dd:c25:c25:dd2c:3eb0/1242c19:dd:d9:dd:c25:c25:dd2c:3ebf
2372c19:dd:d9:dd:c25:c25:dd2c:3ec0/1242c19:dd:d9:dd:c25:c25:dd2c:3ecf
2382c19:dd:d9:dd:c25:c25:dd2c:3ed0/1242c19:dd:d9:dd:c25:c25:dd2c:3edf
2392c19:dd:d9:dd:c25:c25:dd2c:3ee0/1242c19:dd:d9:dd:c25:c25:dd2c:3eef
2402c19:dd:d9:dd:c25:c25:dd2c:3ef0/1242c19:dd:d9:dd:c25:c25:dd2c:3eff
2412c19:dd:d9:dd:c25:c25:dd2c:3f00/1242c19:dd:d9:dd:c25:c25:dd2c:3f0f
2422c19:dd:d9:dd:c25:c25:dd2c:3f10/1242c19:dd:d9:dd:c25:c25:dd2c:3f1f
2432c19:dd:d9:dd:c25:c25:dd2c:3f20/1242c19:dd:d9:dd:c25:c25:dd2c:3f2f
2442c19:dd:d9:dd:c25:c25:dd2c:3f30/1242c19:dd:d9:dd:c25:c25:dd2c:3f3f
2452c19:dd:d9:dd:c25:c25:dd2c:3f40/1242c19:dd:d9:dd:c25:c25:dd2c:3f4f
2462c19:dd:d9:dd:c25:c25:dd2c:3f50/1242c19:dd:d9:dd:c25:c25:dd2c:3f5f
2472c19:dd:d9:dd:c25:c25:dd2c:3f60/1242c19:dd:d9:dd:c25:c25:dd2c:3f6f
2482c19:dd:d9:dd:c25:c25:dd2c:3f70/1242c19:dd:d9:dd:c25:c25:dd2c:3f7f
2492c19:dd:d9:dd:c25:c25:dd2c:3f80/1242c19:dd:d9:dd:c25:c25:dd2c:3f8f
2502c19:dd:d9:dd:c25:c25:dd2c:3f90/1242c19:dd:d9:dd:c25:c25:dd2c:3f9f
2512c19:dd:d9:dd:c25:c25:dd2c:3fa0/1242c19:dd:d9:dd:c25:c25:dd2c:3faf
2522c19:dd:d9:dd:c25:c25:dd2c:3fb0/1242c19:dd:d9:dd:c25:c25:dd2c:3fbf
2532c19:dd:d9:dd:c25:c25:dd2c:3fc0/1242c19:dd:d9:dd:c25:c25:dd2c:3fcf
2542c19:dd:d9:dd:c25:c25:dd2c:3fd0/1242c19:dd:d9:dd:c25:c25:dd2c:3fdf
2552c19:dd:d9:dd:c25:c25:dd2c:3fe0/1242c19:dd:d9:dd:c25:c25:dd2c:3fef
2562c19:dd:d9:dd:c25:c25:dd2c:3ff0/1242c19:dd:d9:dd:c25:c25:dd2c:3fff

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.