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:c25:8008:8000/116
First address
2c19:dd:d9:dd:c25:c25:8008:8000
Last address
2c19:dd:d9:dd:c25:c25:8008:8fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:8008:8000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
8.8.0.0.8.5.2.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:c25:8008:8000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:8008:8000/1242c19:dd:d9:dd:c25:c25:8008:800f
22c19:dd:d9:dd:c25:c25:8008:8010/1242c19:dd:d9:dd:c25:c25:8008:801f
32c19:dd:d9:dd:c25:c25:8008:8020/1242c19:dd:d9:dd:c25:c25:8008:802f
42c19:dd:d9:dd:c25:c25:8008:8030/1242c19:dd:d9:dd:c25:c25:8008:803f
52c19:dd:d9:dd:c25:c25:8008:8040/1242c19:dd:d9:dd:c25:c25:8008:804f
62c19:dd:d9:dd:c25:c25:8008:8050/1242c19:dd:d9:dd:c25:c25:8008:805f
72c19:dd:d9:dd:c25:c25:8008:8060/1242c19:dd:d9:dd:c25:c25:8008:806f
82c19:dd:d9:dd:c25:c25:8008:8070/1242c19:dd:d9:dd:c25:c25:8008:807f
92c19:dd:d9:dd:c25:c25:8008:8080/1242c19:dd:d9:dd:c25:c25:8008:808f
102c19:dd:d9:dd:c25:c25:8008:8090/1242c19:dd:d9:dd:c25:c25:8008:809f
112c19:dd:d9:dd:c25:c25:8008:80a0/1242c19:dd:d9:dd:c25:c25:8008:80af
122c19:dd:d9:dd:c25:c25:8008:80b0/1242c19:dd:d9:dd:c25:c25:8008:80bf
132c19:dd:d9:dd:c25:c25:8008:80c0/1242c19:dd:d9:dd:c25:c25:8008:80cf
142c19:dd:d9:dd:c25:c25:8008:80d0/1242c19:dd:d9:dd:c25:c25:8008:80df
152c19:dd:d9:dd:c25:c25:8008:80e0/1242c19:dd:d9:dd:c25:c25:8008:80ef
162c19:dd:d9:dd:c25:c25:8008:80f0/1242c19:dd:d9:dd:c25:c25:8008:80ff
172c19:dd:d9:dd:c25:c25:8008:8100/1242c19:dd:d9:dd:c25:c25:8008:810f
182c19:dd:d9:dd:c25:c25:8008:8110/1242c19:dd:d9:dd:c25:c25:8008:811f
192c19:dd:d9:dd:c25:c25:8008:8120/1242c19:dd:d9:dd:c25:c25:8008:812f
202c19:dd:d9:dd:c25:c25:8008:8130/1242c19:dd:d9:dd:c25:c25:8008:813f
212c19:dd:d9:dd:c25:c25:8008:8140/1242c19:dd:d9:dd:c25:c25:8008:814f
222c19:dd:d9:dd:c25:c25:8008:8150/1242c19:dd:d9:dd:c25:c25:8008:815f
232c19:dd:d9:dd:c25:c25:8008:8160/1242c19:dd:d9:dd:c25:c25:8008:816f
242c19:dd:d9:dd:c25:c25:8008:8170/1242c19:dd:d9:dd:c25:c25:8008:817f
252c19:dd:d9:dd:c25:c25:8008:8180/1242c19:dd:d9:dd:c25:c25:8008:818f
262c19:dd:d9:dd:c25:c25:8008:8190/1242c19:dd:d9:dd:c25:c25:8008:819f
272c19:dd:d9:dd:c25:c25:8008:81a0/1242c19:dd:d9:dd:c25:c25:8008:81af
282c19:dd:d9:dd:c25:c25:8008:81b0/1242c19:dd:d9:dd:c25:c25:8008:81bf
292c19:dd:d9:dd:c25:c25:8008:81c0/1242c19:dd:d9:dd:c25:c25:8008:81cf
302c19:dd:d9:dd:c25:c25:8008:81d0/1242c19:dd:d9:dd:c25:c25:8008:81df
312c19:dd:d9:dd:c25:c25:8008:81e0/1242c19:dd:d9:dd:c25:c25:8008:81ef
322c19:dd:d9:dd:c25:c25:8008:81f0/1242c19:dd:d9:dd:c25:c25:8008:81ff
332c19:dd:d9:dd:c25:c25:8008:8200/1242c19:dd:d9:dd:c25:c25:8008:820f
342c19:dd:d9:dd:c25:c25:8008:8210/1242c19:dd:d9:dd:c25:c25:8008:821f
352c19:dd:d9:dd:c25:c25:8008:8220/1242c19:dd:d9:dd:c25:c25:8008:822f
362c19:dd:d9:dd:c25:c25:8008:8230/1242c19:dd:d9:dd:c25:c25:8008:823f
372c19:dd:d9:dd:c25:c25:8008:8240/1242c19:dd:d9:dd:c25:c25:8008:824f
382c19:dd:d9:dd:c25:c25:8008:8250/1242c19:dd:d9:dd:c25:c25:8008:825f
392c19:dd:d9:dd:c25:c25:8008:8260/1242c19:dd:d9:dd:c25:c25:8008:826f
402c19:dd:d9:dd:c25:c25:8008:8270/1242c19:dd:d9:dd:c25:c25:8008:827f
412c19:dd:d9:dd:c25:c25:8008:8280/1242c19:dd:d9:dd:c25:c25:8008:828f
422c19:dd:d9:dd:c25:c25:8008:8290/1242c19:dd:d9:dd:c25:c25:8008:829f
432c19:dd:d9:dd:c25:c25:8008:82a0/1242c19:dd:d9:dd:c25:c25:8008:82af
442c19:dd:d9:dd:c25:c25:8008:82b0/1242c19:dd:d9:dd:c25:c25:8008:82bf
452c19:dd:d9:dd:c25:c25:8008:82c0/1242c19:dd:d9:dd:c25:c25:8008:82cf
462c19:dd:d9:dd:c25:c25:8008:82d0/1242c19:dd:d9:dd:c25:c25:8008:82df
472c19:dd:d9:dd:c25:c25:8008:82e0/1242c19:dd:d9:dd:c25:c25:8008:82ef
482c19:dd:d9:dd:c25:c25:8008:82f0/1242c19:dd:d9:dd:c25:c25:8008:82ff
492c19:dd:d9:dd:c25:c25:8008:8300/1242c19:dd:d9:dd:c25:c25:8008:830f
502c19:dd:d9:dd:c25:c25:8008:8310/1242c19:dd:d9:dd:c25:c25:8008:831f
512c19:dd:d9:dd:c25:c25:8008:8320/1242c19:dd:d9:dd:c25:c25:8008:832f
522c19:dd:d9:dd:c25:c25:8008:8330/1242c19:dd:d9:dd:c25:c25:8008:833f
532c19:dd:d9:dd:c25:c25:8008:8340/1242c19:dd:d9:dd:c25:c25:8008:834f
542c19:dd:d9:dd:c25:c25:8008:8350/1242c19:dd:d9:dd:c25:c25:8008:835f
552c19:dd:d9:dd:c25:c25:8008:8360/1242c19:dd:d9:dd:c25:c25:8008:836f
562c19:dd:d9:dd:c25:c25:8008:8370/1242c19:dd:d9:dd:c25:c25:8008:837f
572c19:dd:d9:dd:c25:c25:8008:8380/1242c19:dd:d9:dd:c25:c25:8008:838f
582c19:dd:d9:dd:c25:c25:8008:8390/1242c19:dd:d9:dd:c25:c25:8008:839f
592c19:dd:d9:dd:c25:c25:8008:83a0/1242c19:dd:d9:dd:c25:c25:8008:83af
602c19:dd:d9:dd:c25:c25:8008:83b0/1242c19:dd:d9:dd:c25:c25:8008:83bf
612c19:dd:d9:dd:c25:c25:8008:83c0/1242c19:dd:d9:dd:c25:c25:8008:83cf
622c19:dd:d9:dd:c25:c25:8008:83d0/1242c19:dd:d9:dd:c25:c25:8008:83df
632c19:dd:d9:dd:c25:c25:8008:83e0/1242c19:dd:d9:dd:c25:c25:8008:83ef
642c19:dd:d9:dd:c25:c25:8008:83f0/1242c19:dd:d9:dd:c25:c25:8008:83ff
652c19:dd:d9:dd:c25:c25:8008:8400/1242c19:dd:d9:dd:c25:c25:8008:840f
662c19:dd:d9:dd:c25:c25:8008:8410/1242c19:dd:d9:dd:c25:c25:8008:841f
672c19:dd:d9:dd:c25:c25:8008:8420/1242c19:dd:d9:dd:c25:c25:8008:842f
682c19:dd:d9:dd:c25:c25:8008:8430/1242c19:dd:d9:dd:c25:c25:8008:843f
692c19:dd:d9:dd:c25:c25:8008:8440/1242c19:dd:d9:dd:c25:c25:8008:844f
702c19:dd:d9:dd:c25:c25:8008:8450/1242c19:dd:d9:dd:c25:c25:8008:845f
712c19:dd:d9:dd:c25:c25:8008:8460/1242c19:dd:d9:dd:c25:c25:8008:846f
722c19:dd:d9:dd:c25:c25:8008:8470/1242c19:dd:d9:dd:c25:c25:8008:847f
732c19:dd:d9:dd:c25:c25:8008:8480/1242c19:dd:d9:dd:c25:c25:8008:848f
742c19:dd:d9:dd:c25:c25:8008:8490/1242c19:dd:d9:dd:c25:c25:8008:849f
752c19:dd:d9:dd:c25:c25:8008:84a0/1242c19:dd:d9:dd:c25:c25:8008:84af
762c19:dd:d9:dd:c25:c25:8008:84b0/1242c19:dd:d9:dd:c25:c25:8008:84bf
772c19:dd:d9:dd:c25:c25:8008:84c0/1242c19:dd:d9:dd:c25:c25:8008:84cf
782c19:dd:d9:dd:c25:c25:8008:84d0/1242c19:dd:d9:dd:c25:c25:8008:84df
792c19:dd:d9:dd:c25:c25:8008:84e0/1242c19:dd:d9:dd:c25:c25:8008:84ef
802c19:dd:d9:dd:c25:c25:8008:84f0/1242c19:dd:d9:dd:c25:c25:8008:84ff
812c19:dd:d9:dd:c25:c25:8008:8500/1242c19:dd:d9:dd:c25:c25:8008:850f
822c19:dd:d9:dd:c25:c25:8008:8510/1242c19:dd:d9:dd:c25:c25:8008:851f
832c19:dd:d9:dd:c25:c25:8008:8520/1242c19:dd:d9:dd:c25:c25:8008:852f
842c19:dd:d9:dd:c25:c25:8008:8530/1242c19:dd:d9:dd:c25:c25:8008:853f
852c19:dd:d9:dd:c25:c25:8008:8540/1242c19:dd:d9:dd:c25:c25:8008:854f
862c19:dd:d9:dd:c25:c25:8008:8550/1242c19:dd:d9:dd:c25:c25:8008:855f
872c19:dd:d9:dd:c25:c25:8008:8560/1242c19:dd:d9:dd:c25:c25:8008:856f
882c19:dd:d9:dd:c25:c25:8008:8570/1242c19:dd:d9:dd:c25:c25:8008:857f
892c19:dd:d9:dd:c25:c25:8008:8580/1242c19:dd:d9:dd:c25:c25:8008:858f
902c19:dd:d9:dd:c25:c25:8008:8590/1242c19:dd:d9:dd:c25:c25:8008:859f
912c19:dd:d9:dd:c25:c25:8008:85a0/1242c19:dd:d9:dd:c25:c25:8008:85af
922c19:dd:d9:dd:c25:c25:8008:85b0/1242c19:dd:d9:dd:c25:c25:8008:85bf
932c19:dd:d9:dd:c25:c25:8008:85c0/1242c19:dd:d9:dd:c25:c25:8008:85cf
942c19:dd:d9:dd:c25:c25:8008:85d0/1242c19:dd:d9:dd:c25:c25:8008:85df
952c19:dd:d9:dd:c25:c25:8008:85e0/1242c19:dd:d9:dd:c25:c25:8008:85ef
962c19:dd:d9:dd:c25:c25:8008:85f0/1242c19:dd:d9:dd:c25:c25:8008:85ff
972c19:dd:d9:dd:c25:c25:8008:8600/1242c19:dd:d9:dd:c25:c25:8008:860f
982c19:dd:d9:dd:c25:c25:8008:8610/1242c19:dd:d9:dd:c25:c25:8008:861f
992c19:dd:d9:dd:c25:c25:8008:8620/1242c19:dd:d9:dd:c25:c25:8008:862f
1002c19:dd:d9:dd:c25:c25:8008:8630/1242c19:dd:d9:dd:c25:c25:8008:863f
1012c19:dd:d9:dd:c25:c25:8008:8640/1242c19:dd:d9:dd:c25:c25:8008:864f
1022c19:dd:d9:dd:c25:c25:8008:8650/1242c19:dd:d9:dd:c25:c25:8008:865f
1032c19:dd:d9:dd:c25:c25:8008:8660/1242c19:dd:d9:dd:c25:c25:8008:866f
1042c19:dd:d9:dd:c25:c25:8008:8670/1242c19:dd:d9:dd:c25:c25:8008:867f
1052c19:dd:d9:dd:c25:c25:8008:8680/1242c19:dd:d9:dd:c25:c25:8008:868f
1062c19:dd:d9:dd:c25:c25:8008:8690/1242c19:dd:d9:dd:c25:c25:8008:869f
1072c19:dd:d9:dd:c25:c25:8008:86a0/1242c19:dd:d9:dd:c25:c25:8008:86af
1082c19:dd:d9:dd:c25:c25:8008:86b0/1242c19:dd:d9:dd:c25:c25:8008:86bf
1092c19:dd:d9:dd:c25:c25:8008:86c0/1242c19:dd:d9:dd:c25:c25:8008:86cf
1102c19:dd:d9:dd:c25:c25:8008:86d0/1242c19:dd:d9:dd:c25:c25:8008:86df
1112c19:dd:d9:dd:c25:c25:8008:86e0/1242c19:dd:d9:dd:c25:c25:8008:86ef
1122c19:dd:d9:dd:c25:c25:8008:86f0/1242c19:dd:d9:dd:c25:c25:8008:86ff
1132c19:dd:d9:dd:c25:c25:8008:8700/1242c19:dd:d9:dd:c25:c25:8008:870f
1142c19:dd:d9:dd:c25:c25:8008:8710/1242c19:dd:d9:dd:c25:c25:8008:871f
1152c19:dd:d9:dd:c25:c25:8008:8720/1242c19:dd:d9:dd:c25:c25:8008:872f
1162c19:dd:d9:dd:c25:c25:8008:8730/1242c19:dd:d9:dd:c25:c25:8008:873f
1172c19:dd:d9:dd:c25:c25:8008:8740/1242c19:dd:d9:dd:c25:c25:8008:874f
1182c19:dd:d9:dd:c25:c25:8008:8750/1242c19:dd:d9:dd:c25:c25:8008:875f
1192c19:dd:d9:dd:c25:c25:8008:8760/1242c19:dd:d9:dd:c25:c25:8008:876f
1202c19:dd:d9:dd:c25:c25:8008:8770/1242c19:dd:d9:dd:c25:c25:8008:877f
1212c19:dd:d9:dd:c25:c25:8008:8780/1242c19:dd:d9:dd:c25:c25:8008:878f
1222c19:dd:d9:dd:c25:c25:8008:8790/1242c19:dd:d9:dd:c25:c25:8008:879f
1232c19:dd:d9:dd:c25:c25:8008:87a0/1242c19:dd:d9:dd:c25:c25:8008:87af
1242c19:dd:d9:dd:c25:c25:8008:87b0/1242c19:dd:d9:dd:c25:c25:8008:87bf
1252c19:dd:d9:dd:c25:c25:8008:87c0/1242c19:dd:d9:dd:c25:c25:8008:87cf
1262c19:dd:d9:dd:c25:c25:8008:87d0/1242c19:dd:d9:dd:c25:c25:8008:87df
1272c19:dd:d9:dd:c25:c25:8008:87e0/1242c19:dd:d9:dd:c25:c25:8008:87ef
1282c19:dd:d9:dd:c25:c25:8008:87f0/1242c19:dd:d9:dd:c25:c25:8008:87ff
1292c19:dd:d9:dd:c25:c25:8008:8800/1242c19:dd:d9:dd:c25:c25:8008:880f
1302c19:dd:d9:dd:c25:c25:8008:8810/1242c19:dd:d9:dd:c25:c25:8008:881f
1312c19:dd:d9:dd:c25:c25:8008:8820/1242c19:dd:d9:dd:c25:c25:8008:882f
1322c19:dd:d9:dd:c25:c25:8008:8830/1242c19:dd:d9:dd:c25:c25:8008:883f
1332c19:dd:d9:dd:c25:c25:8008:8840/1242c19:dd:d9:dd:c25:c25:8008:884f
1342c19:dd:d9:dd:c25:c25:8008:8850/1242c19:dd:d9:dd:c25:c25:8008:885f
1352c19:dd:d9:dd:c25:c25:8008:8860/1242c19:dd:d9:dd:c25:c25:8008:886f
1362c19:dd:d9:dd:c25:c25:8008:8870/1242c19:dd:d9:dd:c25:c25:8008:887f
1372c19:dd:d9:dd:c25:c25:8008:8880/1242c19:dd:d9:dd:c25:c25:8008:888f
1382c19:dd:d9:dd:c25:c25:8008:8890/1242c19:dd:d9:dd:c25:c25:8008:889f
1392c19:dd:d9:dd:c25:c25:8008:88a0/1242c19:dd:d9:dd:c25:c25:8008:88af
1402c19:dd:d9:dd:c25:c25:8008:88b0/1242c19:dd:d9:dd:c25:c25:8008:88bf
1412c19:dd:d9:dd:c25:c25:8008:88c0/1242c19:dd:d9:dd:c25:c25:8008:88cf
1422c19:dd:d9:dd:c25:c25:8008:88d0/1242c19:dd:d9:dd:c25:c25:8008:88df
1432c19:dd:d9:dd:c25:c25:8008:88e0/1242c19:dd:d9:dd:c25:c25:8008:88ef
1442c19:dd:d9:dd:c25:c25:8008:88f0/1242c19:dd:d9:dd:c25:c25:8008:88ff
1452c19:dd:d9:dd:c25:c25:8008:8900/1242c19:dd:d9:dd:c25:c25:8008:890f
1462c19:dd:d9:dd:c25:c25:8008:8910/1242c19:dd:d9:dd:c25:c25:8008:891f
1472c19:dd:d9:dd:c25:c25:8008:8920/1242c19:dd:d9:dd:c25:c25:8008:892f
1482c19:dd:d9:dd:c25:c25:8008:8930/1242c19:dd:d9:dd:c25:c25:8008:893f
1492c19:dd:d9:dd:c25:c25:8008:8940/1242c19:dd:d9:dd:c25:c25:8008:894f
1502c19:dd:d9:dd:c25:c25:8008:8950/1242c19:dd:d9:dd:c25:c25:8008:895f
1512c19:dd:d9:dd:c25:c25:8008:8960/1242c19:dd:d9:dd:c25:c25:8008:896f
1522c19:dd:d9:dd:c25:c25:8008:8970/1242c19:dd:d9:dd:c25:c25:8008:897f
1532c19:dd:d9:dd:c25:c25:8008:8980/1242c19:dd:d9:dd:c25:c25:8008:898f
1542c19:dd:d9:dd:c25:c25:8008:8990/1242c19:dd:d9:dd:c25:c25:8008:899f
1552c19:dd:d9:dd:c25:c25:8008:89a0/1242c19:dd:d9:dd:c25:c25:8008:89af
1562c19:dd:d9:dd:c25:c25:8008:89b0/1242c19:dd:d9:dd:c25:c25:8008:89bf
1572c19:dd:d9:dd:c25:c25:8008:89c0/1242c19:dd:d9:dd:c25:c25:8008:89cf
1582c19:dd:d9:dd:c25:c25:8008:89d0/1242c19:dd:d9:dd:c25:c25:8008:89df
1592c19:dd:d9:dd:c25:c25:8008:89e0/1242c19:dd:d9:dd:c25:c25:8008:89ef
1602c19:dd:d9:dd:c25:c25:8008:89f0/1242c19:dd:d9:dd:c25:c25:8008:89ff
1612c19:dd:d9:dd:c25:c25:8008:8a00/1242c19:dd:d9:dd:c25:c25:8008:8a0f
1622c19:dd:d9:dd:c25:c25:8008:8a10/1242c19:dd:d9:dd:c25:c25:8008:8a1f
1632c19:dd:d9:dd:c25:c25:8008:8a20/1242c19:dd:d9:dd:c25:c25:8008:8a2f
1642c19:dd:d9:dd:c25:c25:8008:8a30/1242c19:dd:d9:dd:c25:c25:8008:8a3f
1652c19:dd:d9:dd:c25:c25:8008:8a40/1242c19:dd:d9:dd:c25:c25:8008:8a4f
1662c19:dd:d9:dd:c25:c25:8008:8a50/1242c19:dd:d9:dd:c25:c25:8008:8a5f
1672c19:dd:d9:dd:c25:c25:8008:8a60/1242c19:dd:d9:dd:c25:c25:8008:8a6f
1682c19:dd:d9:dd:c25:c25:8008:8a70/1242c19:dd:d9:dd:c25:c25:8008:8a7f
1692c19:dd:d9:dd:c25:c25:8008:8a80/1242c19:dd:d9:dd:c25:c25:8008:8a8f
1702c19:dd:d9:dd:c25:c25:8008:8a90/1242c19:dd:d9:dd:c25:c25:8008:8a9f
1712c19:dd:d9:dd:c25:c25:8008:8aa0/1242c19:dd:d9:dd:c25:c25:8008:8aaf
1722c19:dd:d9:dd:c25:c25:8008:8ab0/1242c19:dd:d9:dd:c25:c25:8008:8abf
1732c19:dd:d9:dd:c25:c25:8008:8ac0/1242c19:dd:d9:dd:c25:c25:8008:8acf
1742c19:dd:d9:dd:c25:c25:8008:8ad0/1242c19:dd:d9:dd:c25:c25:8008:8adf
1752c19:dd:d9:dd:c25:c25:8008:8ae0/1242c19:dd:d9:dd:c25:c25:8008:8aef
1762c19:dd:d9:dd:c25:c25:8008:8af0/1242c19:dd:d9:dd:c25:c25:8008:8aff
1772c19:dd:d9:dd:c25:c25:8008:8b00/1242c19:dd:d9:dd:c25:c25:8008:8b0f
1782c19:dd:d9:dd:c25:c25:8008:8b10/1242c19:dd:d9:dd:c25:c25:8008:8b1f
1792c19:dd:d9:dd:c25:c25:8008:8b20/1242c19:dd:d9:dd:c25:c25:8008:8b2f
1802c19:dd:d9:dd:c25:c25:8008:8b30/1242c19:dd:d9:dd:c25:c25:8008:8b3f
1812c19:dd:d9:dd:c25:c25:8008:8b40/1242c19:dd:d9:dd:c25:c25:8008:8b4f
1822c19:dd:d9:dd:c25:c25:8008:8b50/1242c19:dd:d9:dd:c25:c25:8008:8b5f
1832c19:dd:d9:dd:c25:c25:8008:8b60/1242c19:dd:d9:dd:c25:c25:8008:8b6f
1842c19:dd:d9:dd:c25:c25:8008:8b70/1242c19:dd:d9:dd:c25:c25:8008:8b7f
1852c19:dd:d9:dd:c25:c25:8008:8b80/1242c19:dd:d9:dd:c25:c25:8008:8b8f
1862c19:dd:d9:dd:c25:c25:8008:8b90/1242c19:dd:d9:dd:c25:c25:8008:8b9f
1872c19:dd:d9:dd:c25:c25:8008:8ba0/1242c19:dd:d9:dd:c25:c25:8008:8baf
1882c19:dd:d9:dd:c25:c25:8008:8bb0/1242c19:dd:d9:dd:c25:c25:8008:8bbf
1892c19:dd:d9:dd:c25:c25:8008:8bc0/1242c19:dd:d9:dd:c25:c25:8008:8bcf
1902c19:dd:d9:dd:c25:c25:8008:8bd0/1242c19:dd:d9:dd:c25:c25:8008:8bdf
1912c19:dd:d9:dd:c25:c25:8008:8be0/1242c19:dd:d9:dd:c25:c25:8008:8bef
1922c19:dd:d9:dd:c25:c25:8008:8bf0/1242c19:dd:d9:dd:c25:c25:8008:8bff
1932c19:dd:d9:dd:c25:c25:8008:8c00/1242c19:dd:d9:dd:c25:c25:8008:8c0f
1942c19:dd:d9:dd:c25:c25:8008:8c10/1242c19:dd:d9:dd:c25:c25:8008:8c1f
1952c19:dd:d9:dd:c25:c25:8008:8c20/1242c19:dd:d9:dd:c25:c25:8008:8c2f
1962c19:dd:d9:dd:c25:c25:8008:8c30/1242c19:dd:d9:dd:c25:c25:8008:8c3f
1972c19:dd:d9:dd:c25:c25:8008:8c40/1242c19:dd:d9:dd:c25:c25:8008:8c4f
1982c19:dd:d9:dd:c25:c25:8008:8c50/1242c19:dd:d9:dd:c25:c25:8008:8c5f
1992c19:dd:d9:dd:c25:c25:8008:8c60/1242c19:dd:d9:dd:c25:c25:8008:8c6f
2002c19:dd:d9:dd:c25:c25:8008:8c70/1242c19:dd:d9:dd:c25:c25:8008:8c7f
2012c19:dd:d9:dd:c25:c25:8008:8c80/1242c19:dd:d9:dd:c25:c25:8008:8c8f
2022c19:dd:d9:dd:c25:c25:8008:8c90/1242c19:dd:d9:dd:c25:c25:8008:8c9f
2032c19:dd:d9:dd:c25:c25:8008:8ca0/1242c19:dd:d9:dd:c25:c25:8008:8caf
2042c19:dd:d9:dd:c25:c25:8008:8cb0/1242c19:dd:d9:dd:c25:c25:8008:8cbf
2052c19:dd:d9:dd:c25:c25:8008:8cc0/1242c19:dd:d9:dd:c25:c25:8008:8ccf
2062c19:dd:d9:dd:c25:c25:8008:8cd0/1242c19:dd:d9:dd:c25:c25:8008:8cdf
2072c19:dd:d9:dd:c25:c25:8008:8ce0/1242c19:dd:d9:dd:c25:c25:8008:8cef
2082c19:dd:d9:dd:c25:c25:8008:8cf0/1242c19:dd:d9:dd:c25:c25:8008:8cff
2092c19:dd:d9:dd:c25:c25:8008:8d00/1242c19:dd:d9:dd:c25:c25:8008:8d0f
2102c19:dd:d9:dd:c25:c25:8008:8d10/1242c19:dd:d9:dd:c25:c25:8008:8d1f
2112c19:dd:d9:dd:c25:c25:8008:8d20/1242c19:dd:d9:dd:c25:c25:8008:8d2f
2122c19:dd:d9:dd:c25:c25:8008:8d30/1242c19:dd:d9:dd:c25:c25:8008:8d3f
2132c19:dd:d9:dd:c25:c25:8008:8d40/1242c19:dd:d9:dd:c25:c25:8008:8d4f
2142c19:dd:d9:dd:c25:c25:8008:8d50/1242c19:dd:d9:dd:c25:c25:8008:8d5f
2152c19:dd:d9:dd:c25:c25:8008:8d60/1242c19:dd:d9:dd:c25:c25:8008:8d6f
2162c19:dd:d9:dd:c25:c25:8008:8d70/1242c19:dd:d9:dd:c25:c25:8008:8d7f
2172c19:dd:d9:dd:c25:c25:8008:8d80/1242c19:dd:d9:dd:c25:c25:8008:8d8f
2182c19:dd:d9:dd:c25:c25:8008:8d90/1242c19:dd:d9:dd:c25:c25:8008:8d9f
2192c19:dd:d9:dd:c25:c25:8008:8da0/1242c19:dd:d9:dd:c25:c25:8008:8daf
2202c19:dd:d9:dd:c25:c25:8008:8db0/1242c19:dd:d9:dd:c25:c25:8008:8dbf
2212c19:dd:d9:dd:c25:c25:8008:8dc0/1242c19:dd:d9:dd:c25:c25:8008:8dcf
2222c19:dd:d9:dd:c25:c25:8008:8dd0/1242c19:dd:d9:dd:c25:c25:8008:8ddf
2232c19:dd:d9:dd:c25:c25:8008:8de0/1242c19:dd:d9:dd:c25:c25:8008:8def
2242c19:dd:d9:dd:c25:c25:8008:8df0/1242c19:dd:d9:dd:c25:c25:8008:8dff
2252c19:dd:d9:dd:c25:c25:8008:8e00/1242c19:dd:d9:dd:c25:c25:8008:8e0f
2262c19:dd:d9:dd:c25:c25:8008:8e10/1242c19:dd:d9:dd:c25:c25:8008:8e1f
2272c19:dd:d9:dd:c25:c25:8008:8e20/1242c19:dd:d9:dd:c25:c25:8008:8e2f
2282c19:dd:d9:dd:c25:c25:8008:8e30/1242c19:dd:d9:dd:c25:c25:8008:8e3f
2292c19:dd:d9:dd:c25:c25:8008:8e40/1242c19:dd:d9:dd:c25:c25:8008:8e4f
2302c19:dd:d9:dd:c25:c25:8008:8e50/1242c19:dd:d9:dd:c25:c25:8008:8e5f
2312c19:dd:d9:dd:c25:c25:8008:8e60/1242c19:dd:d9:dd:c25:c25:8008:8e6f
2322c19:dd:d9:dd:c25:c25:8008:8e70/1242c19:dd:d9:dd:c25:c25:8008:8e7f
2332c19:dd:d9:dd:c25:c25:8008:8e80/1242c19:dd:d9:dd:c25:c25:8008:8e8f
2342c19:dd:d9:dd:c25:c25:8008:8e90/1242c19:dd:d9:dd:c25:c25:8008:8e9f
2352c19:dd:d9:dd:c25:c25:8008:8ea0/1242c19:dd:d9:dd:c25:c25:8008:8eaf
2362c19:dd:d9:dd:c25:c25:8008:8eb0/1242c19:dd:d9:dd:c25:c25:8008:8ebf
2372c19:dd:d9:dd:c25:c25:8008:8ec0/1242c19:dd:d9:dd:c25:c25:8008:8ecf
2382c19:dd:d9:dd:c25:c25:8008:8ed0/1242c19:dd:d9:dd:c25:c25:8008:8edf
2392c19:dd:d9:dd:c25:c25:8008:8ee0/1242c19:dd:d9:dd:c25:c25:8008:8eef
2402c19:dd:d9:dd:c25:c25:8008:8ef0/1242c19:dd:d9:dd:c25:c25:8008:8eff
2412c19:dd:d9:dd:c25:c25:8008:8f00/1242c19:dd:d9:dd:c25:c25:8008:8f0f
2422c19:dd:d9:dd:c25:c25:8008:8f10/1242c19:dd:d9:dd:c25:c25:8008:8f1f
2432c19:dd:d9:dd:c25:c25:8008:8f20/1242c19:dd:d9:dd:c25:c25:8008:8f2f
2442c19:dd:d9:dd:c25:c25:8008:8f30/1242c19:dd:d9:dd:c25:c25:8008:8f3f
2452c19:dd:d9:dd:c25:c25:8008:8f40/1242c19:dd:d9:dd:c25:c25:8008:8f4f
2462c19:dd:d9:dd:c25:c25:8008:8f50/1242c19:dd:d9:dd:c25:c25:8008:8f5f
2472c19:dd:d9:dd:c25:c25:8008:8f60/1242c19:dd:d9:dd:c25:c25:8008:8f6f
2482c19:dd:d9:dd:c25:c25:8008:8f70/1242c19:dd:d9:dd:c25:c25:8008:8f7f
2492c19:dd:d9:dd:c25:c25:8008:8f80/1242c19:dd:d9:dd:c25:c25:8008:8f8f
2502c19:dd:d9:dd:c25:c25:8008:8f90/1242c19:dd:d9:dd:c25:c25:8008:8f9f
2512c19:dd:d9:dd:c25:c25:8008:8fa0/1242c19:dd:d9:dd:c25:c25:8008:8faf
2522c19:dd:d9:dd:c25:c25:8008:8fb0/1242c19:dd:d9:dd:c25:c25:8008:8fbf
2532c19:dd:d9:dd:c25:c25:8008:8fc0/1242c19:dd:d9:dd:c25:c25:8008:8fcf
2542c19:dd:d9:dd:c25:c25:8008:8fd0/1242c19:dd:d9:dd:c25:c25:8008:8fdf
2552c19:dd:d9:dd:c25:c25:8008:8fe0/1242c19:dd:d9:dd:c25:c25:8008:8fef
2562c19:dd:d9:dd:c25:c25:8008:8ff0/1242c19:dd:d9:dd:c25:c25:8008:8fff

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.