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/100
Addresses268,435,456
/64 networksPart of one
Network
2c19:dd:d9:dd:c25:c25:1000:0/100
First address
2c19:dd:d9:dd:c25:c25:1000:0
Last address
2c19:dd:d9:dd:c25:c25:1fff:ffff
Addresses
268,435,456
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:1000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
1.5.2.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/116
/101 (2)/102 (4)/103 (8)/104 (16)/108 (256)/112 (4,096)/116 (65,536)

2c19:dd:d9:dd:c25:c25:1000:0/100 makes 65,536 subnets of /116; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:1000:0/1162c19:dd:d9:dd:c25:c25:1000:fff
22c19:dd:d9:dd:c25:c25:1000:1000/1162c19:dd:d9:dd:c25:c25:1000:1fff
32c19:dd:d9:dd:c25:c25:1000:2000/1162c19:dd:d9:dd:c25:c25:1000:2fff
42c19:dd:d9:dd:c25:c25:1000:3000/1162c19:dd:d9:dd:c25:c25:1000:3fff
52c19:dd:d9:dd:c25:c25:1000:4000/1162c19:dd:d9:dd:c25:c25:1000:4fff
62c19:dd:d9:dd:c25:c25:1000:5000/1162c19:dd:d9:dd:c25:c25:1000:5fff
72c19:dd:d9:dd:c25:c25:1000:6000/1162c19:dd:d9:dd:c25:c25:1000:6fff
82c19:dd:d9:dd:c25:c25:1000:7000/1162c19:dd:d9:dd:c25:c25:1000:7fff
92c19:dd:d9:dd:c25:c25:1000:8000/1162c19:dd:d9:dd:c25:c25:1000:8fff
102c19:dd:d9:dd:c25:c25:1000:9000/1162c19:dd:d9:dd:c25:c25:1000:9fff
112c19:dd:d9:dd:c25:c25:1000:a000/1162c19:dd:d9:dd:c25:c25:1000:afff
122c19:dd:d9:dd:c25:c25:1000:b000/1162c19:dd:d9:dd:c25:c25:1000:bfff
132c19:dd:d9:dd:c25:c25:1000:c000/1162c19:dd:d9:dd:c25:c25:1000:cfff
142c19:dd:d9:dd:c25:c25:1000:d000/1162c19:dd:d9:dd:c25:c25:1000:dfff
152c19:dd:d9:dd:c25:c25:1000:e000/1162c19:dd:d9:dd:c25:c25:1000:efff
162c19:dd:d9:dd:c25:c25:1000:f000/1162c19:dd:d9:dd:c25:c25:1000:ffff
172c19:dd:d9:dd:c25:c25:1001:0/1162c19:dd:d9:dd:c25:c25:1001:fff
182c19:dd:d9:dd:c25:c25:1001:1000/1162c19:dd:d9:dd:c25:c25:1001:1fff
192c19:dd:d9:dd:c25:c25:1001:2000/1162c19:dd:d9:dd:c25:c25:1001:2fff
202c19:dd:d9:dd:c25:c25:1001:3000/1162c19:dd:d9:dd:c25:c25:1001:3fff
212c19:dd:d9:dd:c25:c25:1001:4000/1162c19:dd:d9:dd:c25:c25:1001:4fff
222c19:dd:d9:dd:c25:c25:1001:5000/1162c19:dd:d9:dd:c25:c25:1001:5fff
232c19:dd:d9:dd:c25:c25:1001:6000/1162c19:dd:d9:dd:c25:c25:1001:6fff
242c19:dd:d9:dd:c25:c25:1001:7000/1162c19:dd:d9:dd:c25:c25:1001:7fff
252c19:dd:d9:dd:c25:c25:1001:8000/1162c19:dd:d9:dd:c25:c25:1001:8fff
262c19:dd:d9:dd:c25:c25:1001:9000/1162c19:dd:d9:dd:c25:c25:1001:9fff
272c19:dd:d9:dd:c25:c25:1001:a000/1162c19:dd:d9:dd:c25:c25:1001:afff
282c19:dd:d9:dd:c25:c25:1001:b000/1162c19:dd:d9:dd:c25:c25:1001:bfff
292c19:dd:d9:dd:c25:c25:1001:c000/1162c19:dd:d9:dd:c25:c25:1001:cfff
302c19:dd:d9:dd:c25:c25:1001:d000/1162c19:dd:d9:dd:c25:c25:1001:dfff
312c19:dd:d9:dd:c25:c25:1001:e000/1162c19:dd:d9:dd:c25:c25:1001:efff
322c19:dd:d9:dd:c25:c25:1001:f000/1162c19:dd:d9:dd:c25:c25:1001:ffff
332c19:dd:d9:dd:c25:c25:1002:0/1162c19:dd:d9:dd:c25:c25:1002:fff
342c19:dd:d9:dd:c25:c25:1002:1000/1162c19:dd:d9:dd:c25:c25:1002:1fff
352c19:dd:d9:dd:c25:c25:1002:2000/1162c19:dd:d9:dd:c25:c25:1002:2fff
362c19:dd:d9:dd:c25:c25:1002:3000/1162c19:dd:d9:dd:c25:c25:1002:3fff
372c19:dd:d9:dd:c25:c25:1002:4000/1162c19:dd:d9:dd:c25:c25:1002:4fff
382c19:dd:d9:dd:c25:c25:1002:5000/1162c19:dd:d9:dd:c25:c25:1002:5fff
392c19:dd:d9:dd:c25:c25:1002:6000/1162c19:dd:d9:dd:c25:c25:1002:6fff
402c19:dd:d9:dd:c25:c25:1002:7000/1162c19:dd:d9:dd:c25:c25:1002:7fff
412c19:dd:d9:dd:c25:c25:1002:8000/1162c19:dd:d9:dd:c25:c25:1002:8fff
422c19:dd:d9:dd:c25:c25:1002:9000/1162c19:dd:d9:dd:c25:c25:1002:9fff
432c19:dd:d9:dd:c25:c25:1002:a000/1162c19:dd:d9:dd:c25:c25:1002:afff
442c19:dd:d9:dd:c25:c25:1002:b000/1162c19:dd:d9:dd:c25:c25:1002:bfff
452c19:dd:d9:dd:c25:c25:1002:c000/1162c19:dd:d9:dd:c25:c25:1002:cfff
462c19:dd:d9:dd:c25:c25:1002:d000/1162c19:dd:d9:dd:c25:c25:1002:dfff
472c19:dd:d9:dd:c25:c25:1002:e000/1162c19:dd:d9:dd:c25:c25:1002:efff
482c19:dd:d9:dd:c25:c25:1002:f000/1162c19:dd:d9:dd:c25:c25:1002:ffff
492c19:dd:d9:dd:c25:c25:1003:0/1162c19:dd:d9:dd:c25:c25:1003:fff
502c19:dd:d9:dd:c25:c25:1003:1000/1162c19:dd:d9:dd:c25:c25:1003:1fff
512c19:dd:d9:dd:c25:c25:1003:2000/1162c19:dd:d9:dd:c25:c25:1003:2fff
522c19:dd:d9:dd:c25:c25:1003:3000/1162c19:dd:d9:dd:c25:c25:1003:3fff
532c19:dd:d9:dd:c25:c25:1003:4000/1162c19:dd:d9:dd:c25:c25:1003:4fff
542c19:dd:d9:dd:c25:c25:1003:5000/1162c19:dd:d9:dd:c25:c25:1003:5fff
552c19:dd:d9:dd:c25:c25:1003:6000/1162c19:dd:d9:dd:c25:c25:1003:6fff
562c19:dd:d9:dd:c25:c25:1003:7000/1162c19:dd:d9:dd:c25:c25:1003:7fff
572c19:dd:d9:dd:c25:c25:1003:8000/1162c19:dd:d9:dd:c25:c25:1003:8fff
582c19:dd:d9:dd:c25:c25:1003:9000/1162c19:dd:d9:dd:c25:c25:1003:9fff
592c19:dd:d9:dd:c25:c25:1003:a000/1162c19:dd:d9:dd:c25:c25:1003:afff
602c19:dd:d9:dd:c25:c25:1003:b000/1162c19:dd:d9:dd:c25:c25:1003:bfff
612c19:dd:d9:dd:c25:c25:1003:c000/1162c19:dd:d9:dd:c25:c25:1003:cfff
622c19:dd:d9:dd:c25:c25:1003:d000/1162c19:dd:d9:dd:c25:c25:1003:dfff
632c19:dd:d9:dd:c25:c25:1003:e000/1162c19:dd:d9:dd:c25:c25:1003:efff
642c19:dd:d9:dd:c25:c25:1003:f000/1162c19:dd:d9:dd:c25:c25:1003:ffff
652c19:dd:d9:dd:c25:c25:1004:0/1162c19:dd:d9:dd:c25:c25:1004:fff
662c19:dd:d9:dd:c25:c25:1004:1000/1162c19:dd:d9:dd:c25:c25:1004:1fff
672c19:dd:d9:dd:c25:c25:1004:2000/1162c19:dd:d9:dd:c25:c25:1004:2fff
682c19:dd:d9:dd:c25:c25:1004:3000/1162c19:dd:d9:dd:c25:c25:1004:3fff
692c19:dd:d9:dd:c25:c25:1004:4000/1162c19:dd:d9:dd:c25:c25:1004:4fff
702c19:dd:d9:dd:c25:c25:1004:5000/1162c19:dd:d9:dd:c25:c25:1004:5fff
712c19:dd:d9:dd:c25:c25:1004:6000/1162c19:dd:d9:dd:c25:c25:1004:6fff
722c19:dd:d9:dd:c25:c25:1004:7000/1162c19:dd:d9:dd:c25:c25:1004:7fff
732c19:dd:d9:dd:c25:c25:1004:8000/1162c19:dd:d9:dd:c25:c25:1004:8fff
742c19:dd:d9:dd:c25:c25:1004:9000/1162c19:dd:d9:dd:c25:c25:1004:9fff
752c19:dd:d9:dd:c25:c25:1004:a000/1162c19:dd:d9:dd:c25:c25:1004:afff
762c19:dd:d9:dd:c25:c25:1004:b000/1162c19:dd:d9:dd:c25:c25:1004:bfff
772c19:dd:d9:dd:c25:c25:1004:c000/1162c19:dd:d9:dd:c25:c25:1004:cfff
782c19:dd:d9:dd:c25:c25:1004:d000/1162c19:dd:d9:dd:c25:c25:1004:dfff
792c19:dd:d9:dd:c25:c25:1004:e000/1162c19:dd:d9:dd:c25:c25:1004:efff
802c19:dd:d9:dd:c25:c25:1004:f000/1162c19:dd:d9:dd:c25:c25:1004:ffff
812c19:dd:d9:dd:c25:c25:1005:0/1162c19:dd:d9:dd:c25:c25:1005:fff
822c19:dd:d9:dd:c25:c25:1005:1000/1162c19:dd:d9:dd:c25:c25:1005:1fff
832c19:dd:d9:dd:c25:c25:1005:2000/1162c19:dd:d9:dd:c25:c25:1005:2fff
842c19:dd:d9:dd:c25:c25:1005:3000/1162c19:dd:d9:dd:c25:c25:1005:3fff
852c19:dd:d9:dd:c25:c25:1005:4000/1162c19:dd:d9:dd:c25:c25:1005:4fff
862c19:dd:d9:dd:c25:c25:1005:5000/1162c19:dd:d9:dd:c25:c25:1005:5fff
872c19:dd:d9:dd:c25:c25:1005:6000/1162c19:dd:d9:dd:c25:c25:1005:6fff
882c19:dd:d9:dd:c25:c25:1005:7000/1162c19:dd:d9:dd:c25:c25:1005:7fff
892c19:dd:d9:dd:c25:c25:1005:8000/1162c19:dd:d9:dd:c25:c25:1005:8fff
902c19:dd:d9:dd:c25:c25:1005:9000/1162c19:dd:d9:dd:c25:c25:1005:9fff
912c19:dd:d9:dd:c25:c25:1005:a000/1162c19:dd:d9:dd:c25:c25:1005:afff
922c19:dd:d9:dd:c25:c25:1005:b000/1162c19:dd:d9:dd:c25:c25:1005:bfff
932c19:dd:d9:dd:c25:c25:1005:c000/1162c19:dd:d9:dd:c25:c25:1005:cfff
942c19:dd:d9:dd:c25:c25:1005:d000/1162c19:dd:d9:dd:c25:c25:1005:dfff
952c19:dd:d9:dd:c25:c25:1005:e000/1162c19:dd:d9:dd:c25:c25:1005:efff
962c19:dd:d9:dd:c25:c25:1005:f000/1162c19:dd:d9:dd:c25:c25:1005:ffff
972c19:dd:d9:dd:c25:c25:1006:0/1162c19:dd:d9:dd:c25:c25:1006:fff
982c19:dd:d9:dd:c25:c25:1006:1000/1162c19:dd:d9:dd:c25:c25:1006:1fff
992c19:dd:d9:dd:c25:c25:1006:2000/1162c19:dd:d9:dd:c25:c25:1006:2fff
1002c19:dd:d9:dd:c25:c25:1006:3000/1162c19:dd:d9:dd:c25:c25:1006:3fff
1012c19:dd:d9:dd:c25:c25:1006:4000/1162c19:dd:d9:dd:c25:c25:1006:4fff
1022c19:dd:d9:dd:c25:c25:1006:5000/1162c19:dd:d9:dd:c25:c25:1006:5fff
1032c19:dd:d9:dd:c25:c25:1006:6000/1162c19:dd:d9:dd:c25:c25:1006:6fff
1042c19:dd:d9:dd:c25:c25:1006:7000/1162c19:dd:d9:dd:c25:c25:1006:7fff
1052c19:dd:d9:dd:c25:c25:1006:8000/1162c19:dd:d9:dd:c25:c25:1006:8fff
1062c19:dd:d9:dd:c25:c25:1006:9000/1162c19:dd:d9:dd:c25:c25:1006:9fff
1072c19:dd:d9:dd:c25:c25:1006:a000/1162c19:dd:d9:dd:c25:c25:1006:afff
1082c19:dd:d9:dd:c25:c25:1006:b000/1162c19:dd:d9:dd:c25:c25:1006:bfff
1092c19:dd:d9:dd:c25:c25:1006:c000/1162c19:dd:d9:dd:c25:c25:1006:cfff
1102c19:dd:d9:dd:c25:c25:1006:d000/1162c19:dd:d9:dd:c25:c25:1006:dfff
1112c19:dd:d9:dd:c25:c25:1006:e000/1162c19:dd:d9:dd:c25:c25:1006:efff
1122c19:dd:d9:dd:c25:c25:1006:f000/1162c19:dd:d9:dd:c25:c25:1006:ffff
1132c19:dd:d9:dd:c25:c25:1007:0/1162c19:dd:d9:dd:c25:c25:1007:fff
1142c19:dd:d9:dd:c25:c25:1007:1000/1162c19:dd:d9:dd:c25:c25:1007:1fff
1152c19:dd:d9:dd:c25:c25:1007:2000/1162c19:dd:d9:dd:c25:c25:1007:2fff
1162c19:dd:d9:dd:c25:c25:1007:3000/1162c19:dd:d9:dd:c25:c25:1007:3fff
1172c19:dd:d9:dd:c25:c25:1007:4000/1162c19:dd:d9:dd:c25:c25:1007:4fff
1182c19:dd:d9:dd:c25:c25:1007:5000/1162c19:dd:d9:dd:c25:c25:1007:5fff
1192c19:dd:d9:dd:c25:c25:1007:6000/1162c19:dd:d9:dd:c25:c25:1007:6fff
1202c19:dd:d9:dd:c25:c25:1007:7000/1162c19:dd:d9:dd:c25:c25:1007:7fff
1212c19:dd:d9:dd:c25:c25:1007:8000/1162c19:dd:d9:dd:c25:c25:1007:8fff
1222c19:dd:d9:dd:c25:c25:1007:9000/1162c19:dd:d9:dd:c25:c25:1007:9fff
1232c19:dd:d9:dd:c25:c25:1007:a000/1162c19:dd:d9:dd:c25:c25:1007:afff
1242c19:dd:d9:dd:c25:c25:1007:b000/1162c19:dd:d9:dd:c25:c25:1007:bfff
1252c19:dd:d9:dd:c25:c25:1007:c000/1162c19:dd:d9:dd:c25:c25:1007:cfff
1262c19:dd:d9:dd:c25:c25:1007:d000/1162c19:dd:d9:dd:c25:c25:1007:dfff
1272c19:dd:d9:dd:c25:c25:1007:e000/1162c19:dd:d9:dd:c25:c25:1007:efff
1282c19:dd:d9:dd:c25:c25:1007:f000/1162c19:dd:d9:dd:c25:c25:1007:ffff
1292c19:dd:d9:dd:c25:c25:1008:0/1162c19:dd:d9:dd:c25:c25:1008:fff
1302c19:dd:d9:dd:c25:c25:1008:1000/1162c19:dd:d9:dd:c25:c25:1008:1fff
1312c19:dd:d9:dd:c25:c25:1008:2000/1162c19:dd:d9:dd:c25:c25:1008:2fff
1322c19:dd:d9:dd:c25:c25:1008:3000/1162c19:dd:d9:dd:c25:c25:1008:3fff
1332c19:dd:d9:dd:c25:c25:1008:4000/1162c19:dd:d9:dd:c25:c25:1008:4fff
1342c19:dd:d9:dd:c25:c25:1008:5000/1162c19:dd:d9:dd:c25:c25:1008:5fff
1352c19:dd:d9:dd:c25:c25:1008:6000/1162c19:dd:d9:dd:c25:c25:1008:6fff
1362c19:dd:d9:dd:c25:c25:1008:7000/1162c19:dd:d9:dd:c25:c25:1008:7fff
1372c19:dd:d9:dd:c25:c25:1008:8000/1162c19:dd:d9:dd:c25:c25:1008:8fff
1382c19:dd:d9:dd:c25:c25:1008:9000/1162c19:dd:d9:dd:c25:c25:1008:9fff
1392c19:dd:d9:dd:c25:c25:1008:a000/1162c19:dd:d9:dd:c25:c25:1008:afff
1402c19:dd:d9:dd:c25:c25:1008:b000/1162c19:dd:d9:dd:c25:c25:1008:bfff
1412c19:dd:d9:dd:c25:c25:1008:c000/1162c19:dd:d9:dd:c25:c25:1008:cfff
1422c19:dd:d9:dd:c25:c25:1008:d000/1162c19:dd:d9:dd:c25:c25:1008:dfff
1432c19:dd:d9:dd:c25:c25:1008:e000/1162c19:dd:d9:dd:c25:c25:1008:efff
1442c19:dd:d9:dd:c25:c25:1008:f000/1162c19:dd:d9:dd:c25:c25:1008:ffff
1452c19:dd:d9:dd:c25:c25:1009:0/1162c19:dd:d9:dd:c25:c25:1009:fff
1462c19:dd:d9:dd:c25:c25:1009:1000/1162c19:dd:d9:dd:c25:c25:1009:1fff
1472c19:dd:d9:dd:c25:c25:1009:2000/1162c19:dd:d9:dd:c25:c25:1009:2fff
1482c19:dd:d9:dd:c25:c25:1009:3000/1162c19:dd:d9:dd:c25:c25:1009:3fff
1492c19:dd:d9:dd:c25:c25:1009:4000/1162c19:dd:d9:dd:c25:c25:1009:4fff
1502c19:dd:d9:dd:c25:c25:1009:5000/1162c19:dd:d9:dd:c25:c25:1009:5fff
1512c19:dd:d9:dd:c25:c25:1009:6000/1162c19:dd:d9:dd:c25:c25:1009:6fff
1522c19:dd:d9:dd:c25:c25:1009:7000/1162c19:dd:d9:dd:c25:c25:1009:7fff
1532c19:dd:d9:dd:c25:c25:1009:8000/1162c19:dd:d9:dd:c25:c25:1009:8fff
1542c19:dd:d9:dd:c25:c25:1009:9000/1162c19:dd:d9:dd:c25:c25:1009:9fff
1552c19:dd:d9:dd:c25:c25:1009:a000/1162c19:dd:d9:dd:c25:c25:1009:afff
1562c19:dd:d9:dd:c25:c25:1009:b000/1162c19:dd:d9:dd:c25:c25:1009:bfff
1572c19:dd:d9:dd:c25:c25:1009:c000/1162c19:dd:d9:dd:c25:c25:1009:cfff
1582c19:dd:d9:dd:c25:c25:1009:d000/1162c19:dd:d9:dd:c25:c25:1009:dfff
1592c19:dd:d9:dd:c25:c25:1009:e000/1162c19:dd:d9:dd:c25:c25:1009:efff
1602c19:dd:d9:dd:c25:c25:1009:f000/1162c19:dd:d9:dd:c25:c25:1009:ffff
1612c19:dd:d9:dd:c25:c25:100a:0/1162c19:dd:d9:dd:c25:c25:100a:fff
1622c19:dd:d9:dd:c25:c25:100a:1000/1162c19:dd:d9:dd:c25:c25:100a:1fff
1632c19:dd:d9:dd:c25:c25:100a:2000/1162c19:dd:d9:dd:c25:c25:100a:2fff
1642c19:dd:d9:dd:c25:c25:100a:3000/1162c19:dd:d9:dd:c25:c25:100a:3fff
1652c19:dd:d9:dd:c25:c25:100a:4000/1162c19:dd:d9:dd:c25:c25:100a:4fff
1662c19:dd:d9:dd:c25:c25:100a:5000/1162c19:dd:d9:dd:c25:c25:100a:5fff
1672c19:dd:d9:dd:c25:c25:100a:6000/1162c19:dd:d9:dd:c25:c25:100a:6fff
1682c19:dd:d9:dd:c25:c25:100a:7000/1162c19:dd:d9:dd:c25:c25:100a:7fff
1692c19:dd:d9:dd:c25:c25:100a:8000/1162c19:dd:d9:dd:c25:c25:100a:8fff
1702c19:dd:d9:dd:c25:c25:100a:9000/1162c19:dd:d9:dd:c25:c25:100a:9fff
1712c19:dd:d9:dd:c25:c25:100a:a000/1162c19:dd:d9:dd:c25:c25:100a:afff
1722c19:dd:d9:dd:c25:c25:100a:b000/1162c19:dd:d9:dd:c25:c25:100a:bfff
1732c19:dd:d9:dd:c25:c25:100a:c000/1162c19:dd:d9:dd:c25:c25:100a:cfff
1742c19:dd:d9:dd:c25:c25:100a:d000/1162c19:dd:d9:dd:c25:c25:100a:dfff
1752c19:dd:d9:dd:c25:c25:100a:e000/1162c19:dd:d9:dd:c25:c25:100a:efff
1762c19:dd:d9:dd:c25:c25:100a:f000/1162c19:dd:d9:dd:c25:c25:100a:ffff
1772c19:dd:d9:dd:c25:c25:100b:0/1162c19:dd:d9:dd:c25:c25:100b:fff
1782c19:dd:d9:dd:c25:c25:100b:1000/1162c19:dd:d9:dd:c25:c25:100b:1fff
1792c19:dd:d9:dd:c25:c25:100b:2000/1162c19:dd:d9:dd:c25:c25:100b:2fff
1802c19:dd:d9:dd:c25:c25:100b:3000/1162c19:dd:d9:dd:c25:c25:100b:3fff
1812c19:dd:d9:dd:c25:c25:100b:4000/1162c19:dd:d9:dd:c25:c25:100b:4fff
1822c19:dd:d9:dd:c25:c25:100b:5000/1162c19:dd:d9:dd:c25:c25:100b:5fff
1832c19:dd:d9:dd:c25:c25:100b:6000/1162c19:dd:d9:dd:c25:c25:100b:6fff
1842c19:dd:d9:dd:c25:c25:100b:7000/1162c19:dd:d9:dd:c25:c25:100b:7fff
1852c19:dd:d9:dd:c25:c25:100b:8000/1162c19:dd:d9:dd:c25:c25:100b:8fff
1862c19:dd:d9:dd:c25:c25:100b:9000/1162c19:dd:d9:dd:c25:c25:100b:9fff
1872c19:dd:d9:dd:c25:c25:100b:a000/1162c19:dd:d9:dd:c25:c25:100b:afff
1882c19:dd:d9:dd:c25:c25:100b:b000/1162c19:dd:d9:dd:c25:c25:100b:bfff
1892c19:dd:d9:dd:c25:c25:100b:c000/1162c19:dd:d9:dd:c25:c25:100b:cfff
1902c19:dd:d9:dd:c25:c25:100b:d000/1162c19:dd:d9:dd:c25:c25:100b:dfff
1912c19:dd:d9:dd:c25:c25:100b:e000/1162c19:dd:d9:dd:c25:c25:100b:efff
1922c19:dd:d9:dd:c25:c25:100b:f000/1162c19:dd:d9:dd:c25:c25:100b:ffff
1932c19:dd:d9:dd:c25:c25:100c:0/1162c19:dd:d9:dd:c25:c25:100c:fff
1942c19:dd:d9:dd:c25:c25:100c:1000/1162c19:dd:d9:dd:c25:c25:100c:1fff
1952c19:dd:d9:dd:c25:c25:100c:2000/1162c19:dd:d9:dd:c25:c25:100c:2fff
1962c19:dd:d9:dd:c25:c25:100c:3000/1162c19:dd:d9:dd:c25:c25:100c:3fff
1972c19:dd:d9:dd:c25:c25:100c:4000/1162c19:dd:d9:dd:c25:c25:100c:4fff
1982c19:dd:d9:dd:c25:c25:100c:5000/1162c19:dd:d9:dd:c25:c25:100c:5fff
1992c19:dd:d9:dd:c25:c25:100c:6000/1162c19:dd:d9:dd:c25:c25:100c:6fff
2002c19:dd:d9:dd:c25:c25:100c:7000/1162c19:dd:d9:dd:c25:c25:100c:7fff
2012c19:dd:d9:dd:c25:c25:100c:8000/1162c19:dd:d9:dd:c25:c25:100c:8fff
2022c19:dd:d9:dd:c25:c25:100c:9000/1162c19:dd:d9:dd:c25:c25:100c:9fff
2032c19:dd:d9:dd:c25:c25:100c:a000/1162c19:dd:d9:dd:c25:c25:100c:afff
2042c19:dd:d9:dd:c25:c25:100c:b000/1162c19:dd:d9:dd:c25:c25:100c:bfff
2052c19:dd:d9:dd:c25:c25:100c:c000/1162c19:dd:d9:dd:c25:c25:100c:cfff
2062c19:dd:d9:dd:c25:c25:100c:d000/1162c19:dd:d9:dd:c25:c25:100c:dfff
2072c19:dd:d9:dd:c25:c25:100c:e000/1162c19:dd:d9:dd:c25:c25:100c:efff
2082c19:dd:d9:dd:c25:c25:100c:f000/1162c19:dd:d9:dd:c25:c25:100c:ffff
2092c19:dd:d9:dd:c25:c25:100d:0/1162c19:dd:d9:dd:c25:c25:100d:fff
2102c19:dd:d9:dd:c25:c25:100d:1000/1162c19:dd:d9:dd:c25:c25:100d:1fff
2112c19:dd:d9:dd:c25:c25:100d:2000/1162c19:dd:d9:dd:c25:c25:100d:2fff
2122c19:dd:d9:dd:c25:c25:100d:3000/1162c19:dd:d9:dd:c25:c25:100d:3fff
2132c19:dd:d9:dd:c25:c25:100d:4000/1162c19:dd:d9:dd:c25:c25:100d:4fff
2142c19:dd:d9:dd:c25:c25:100d:5000/1162c19:dd:d9:dd:c25:c25:100d:5fff
2152c19:dd:d9:dd:c25:c25:100d:6000/1162c19:dd:d9:dd:c25:c25:100d:6fff
2162c19:dd:d9:dd:c25:c25:100d:7000/1162c19:dd:d9:dd:c25:c25:100d:7fff
2172c19:dd:d9:dd:c25:c25:100d:8000/1162c19:dd:d9:dd:c25:c25:100d:8fff
2182c19:dd:d9:dd:c25:c25:100d:9000/1162c19:dd:d9:dd:c25:c25:100d:9fff
2192c19:dd:d9:dd:c25:c25:100d:a000/1162c19:dd:d9:dd:c25:c25:100d:afff
2202c19:dd:d9:dd:c25:c25:100d:b000/1162c19:dd:d9:dd:c25:c25:100d:bfff
2212c19:dd:d9:dd:c25:c25:100d:c000/1162c19:dd:d9:dd:c25:c25:100d:cfff
2222c19:dd:d9:dd:c25:c25:100d:d000/1162c19:dd:d9:dd:c25:c25:100d:dfff
2232c19:dd:d9:dd:c25:c25:100d:e000/1162c19:dd:d9:dd:c25:c25:100d:efff
2242c19:dd:d9:dd:c25:c25:100d:f000/1162c19:dd:d9:dd:c25:c25:100d:ffff
2252c19:dd:d9:dd:c25:c25:100e:0/1162c19:dd:d9:dd:c25:c25:100e:fff
2262c19:dd:d9:dd:c25:c25:100e:1000/1162c19:dd:d9:dd:c25:c25:100e:1fff
2272c19:dd:d9:dd:c25:c25:100e:2000/1162c19:dd:d9:dd:c25:c25:100e:2fff
2282c19:dd:d9:dd:c25:c25:100e:3000/1162c19:dd:d9:dd:c25:c25:100e:3fff
2292c19:dd:d9:dd:c25:c25:100e:4000/1162c19:dd:d9:dd:c25:c25:100e:4fff
2302c19:dd:d9:dd:c25:c25:100e:5000/1162c19:dd:d9:dd:c25:c25:100e:5fff
2312c19:dd:d9:dd:c25:c25:100e:6000/1162c19:dd:d9:dd:c25:c25:100e:6fff
2322c19:dd:d9:dd:c25:c25:100e:7000/1162c19:dd:d9:dd:c25:c25:100e:7fff
2332c19:dd:d9:dd:c25:c25:100e:8000/1162c19:dd:d9:dd:c25:c25:100e:8fff
2342c19:dd:d9:dd:c25:c25:100e:9000/1162c19:dd:d9:dd:c25:c25:100e:9fff
2352c19:dd:d9:dd:c25:c25:100e:a000/1162c19:dd:d9:dd:c25:c25:100e:afff
2362c19:dd:d9:dd:c25:c25:100e:b000/1162c19:dd:d9:dd:c25:c25:100e:bfff
2372c19:dd:d9:dd:c25:c25:100e:c000/1162c19:dd:d9:dd:c25:c25:100e:cfff
2382c19:dd:d9:dd:c25:c25:100e:d000/1162c19:dd:d9:dd:c25:c25:100e:dfff
2392c19:dd:d9:dd:c25:c25:100e:e000/1162c19:dd:d9:dd:c25:c25:100e:efff
2402c19:dd:d9:dd:c25:c25:100e:f000/1162c19:dd:d9:dd:c25:c25:100e:ffff
2412c19:dd:d9:dd:c25:c25:100f:0/1162c19:dd:d9:dd:c25:c25:100f:fff
2422c19:dd:d9:dd:c25:c25:100f:1000/1162c19:dd:d9:dd:c25:c25:100f:1fff
2432c19:dd:d9:dd:c25:c25:100f:2000/1162c19:dd:d9:dd:c25:c25:100f:2fff
2442c19:dd:d9:dd:c25:c25:100f:3000/1162c19:dd:d9:dd:c25:c25:100f:3fff
2452c19:dd:d9:dd:c25:c25:100f:4000/1162c19:dd:d9:dd:c25:c25:100f:4fff
2462c19:dd:d9:dd:c25:c25:100f:5000/1162c19:dd:d9:dd:c25:c25:100f:5fff
2472c19:dd:d9:dd:c25:c25:100f:6000/1162c19:dd:d9:dd:c25:c25:100f:6fff
2482c19:dd:d9:dd:c25:c25:100f:7000/1162c19:dd:d9:dd:c25:c25:100f:7fff
2492c19:dd:d9:dd:c25:c25:100f:8000/1162c19:dd:d9:dd:c25:c25:100f:8fff
2502c19:dd:d9:dd:c25:c25:100f:9000/1162c19:dd:d9:dd:c25:c25:100f:9fff
2512c19:dd:d9:dd:c25:c25:100f:a000/1162c19:dd:d9:dd:c25:c25:100f:afff
2522c19:dd:d9:dd:c25:c25:100f:b000/1162c19:dd:d9:dd:c25:c25:100f:bfff
2532c19:dd:d9:dd:c25:c25:100f:c000/1162c19:dd:d9:dd:c25:c25:100f:cfff
2542c19:dd:d9:dd:c25:c25:100f:d000/1162c19:dd:d9:dd:c25:c25:100f:dfff
2552c19:dd:d9:dd:c25:c25:100f:e000/1162c19:dd:d9:dd:c25:c25:100f:efff
2562c19:dd:d9:dd:c25:c25:100f:f000/1162c19:dd:d9:dd:c25:c25:100f:ffff

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.