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:c25:2005:9000/116
First address
2c19:dd:d9:dd:c25:c25:2005:9000
Last address
2c19:dd:d9:dd:c25:c25:2005:9fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:2005:9000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
9.5.0.0.2.5.2.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:c25:2005:9000/116 makes 256 subnets of /124.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:2005:9000/1242c19:dd:d9:dd:c25:c25:2005:900f
22c19:dd:d9:dd:c25:c25:2005:9010/1242c19:dd:d9:dd:c25:c25:2005:901f
32c19:dd:d9:dd:c25:c25:2005:9020/1242c19:dd:d9:dd:c25:c25:2005:902f
42c19:dd:d9:dd:c25:c25:2005:9030/1242c19:dd:d9:dd:c25:c25:2005:903f
52c19:dd:d9:dd:c25:c25:2005:9040/1242c19:dd:d9:dd:c25:c25:2005:904f
62c19:dd:d9:dd:c25:c25:2005:9050/1242c19:dd:d9:dd:c25:c25:2005:905f
72c19:dd:d9:dd:c25:c25:2005:9060/1242c19:dd:d9:dd:c25:c25:2005:906f
82c19:dd:d9:dd:c25:c25:2005:9070/1242c19:dd:d9:dd:c25:c25:2005:907f
92c19:dd:d9:dd:c25:c25:2005:9080/1242c19:dd:d9:dd:c25:c25:2005:908f
102c19:dd:d9:dd:c25:c25:2005:9090/1242c19:dd:d9:dd:c25:c25:2005:909f
112c19:dd:d9:dd:c25:c25:2005:90a0/1242c19:dd:d9:dd:c25:c25:2005:90af
122c19:dd:d9:dd:c25:c25:2005:90b0/1242c19:dd:d9:dd:c25:c25:2005:90bf
132c19:dd:d9:dd:c25:c25:2005:90c0/1242c19:dd:d9:dd:c25:c25:2005:90cf
142c19:dd:d9:dd:c25:c25:2005:90d0/1242c19:dd:d9:dd:c25:c25:2005:90df
152c19:dd:d9:dd:c25:c25:2005:90e0/1242c19:dd:d9:dd:c25:c25:2005:90ef
162c19:dd:d9:dd:c25:c25:2005:90f0/1242c19:dd:d9:dd:c25:c25:2005:90ff
172c19:dd:d9:dd:c25:c25:2005:9100/1242c19:dd:d9:dd:c25:c25:2005:910f
182c19:dd:d9:dd:c25:c25:2005:9110/1242c19:dd:d9:dd:c25:c25:2005:911f
192c19:dd:d9:dd:c25:c25:2005:9120/1242c19:dd:d9:dd:c25:c25:2005:912f
202c19:dd:d9:dd:c25:c25:2005:9130/1242c19:dd:d9:dd:c25:c25:2005:913f
212c19:dd:d9:dd:c25:c25:2005:9140/1242c19:dd:d9:dd:c25:c25:2005:914f
222c19:dd:d9:dd:c25:c25:2005:9150/1242c19:dd:d9:dd:c25:c25:2005:915f
232c19:dd:d9:dd:c25:c25:2005:9160/1242c19:dd:d9:dd:c25:c25:2005:916f
242c19:dd:d9:dd:c25:c25:2005:9170/1242c19:dd:d9:dd:c25:c25:2005:917f
252c19:dd:d9:dd:c25:c25:2005:9180/1242c19:dd:d9:dd:c25:c25:2005:918f
262c19:dd:d9:dd:c25:c25:2005:9190/1242c19:dd:d9:dd:c25:c25:2005:919f
272c19:dd:d9:dd:c25:c25:2005:91a0/1242c19:dd:d9:dd:c25:c25:2005:91af
282c19:dd:d9:dd:c25:c25:2005:91b0/1242c19:dd:d9:dd:c25:c25:2005:91bf
292c19:dd:d9:dd:c25:c25:2005:91c0/1242c19:dd:d9:dd:c25:c25:2005:91cf
302c19:dd:d9:dd:c25:c25:2005:91d0/1242c19:dd:d9:dd:c25:c25:2005:91df
312c19:dd:d9:dd:c25:c25:2005:91e0/1242c19:dd:d9:dd:c25:c25:2005:91ef
322c19:dd:d9:dd:c25:c25:2005:91f0/1242c19:dd:d9:dd:c25:c25:2005:91ff
332c19:dd:d9:dd:c25:c25:2005:9200/1242c19:dd:d9:dd:c25:c25:2005:920f
342c19:dd:d9:dd:c25:c25:2005:9210/1242c19:dd:d9:dd:c25:c25:2005:921f
352c19:dd:d9:dd:c25:c25:2005:9220/1242c19:dd:d9:dd:c25:c25:2005:922f
362c19:dd:d9:dd:c25:c25:2005:9230/1242c19:dd:d9:dd:c25:c25:2005:923f
372c19:dd:d9:dd:c25:c25:2005:9240/1242c19:dd:d9:dd:c25:c25:2005:924f
382c19:dd:d9:dd:c25:c25:2005:9250/1242c19:dd:d9:dd:c25:c25:2005:925f
392c19:dd:d9:dd:c25:c25:2005:9260/1242c19:dd:d9:dd:c25:c25:2005:926f
402c19:dd:d9:dd:c25:c25:2005:9270/1242c19:dd:d9:dd:c25:c25:2005:927f
412c19:dd:d9:dd:c25:c25:2005:9280/1242c19:dd:d9:dd:c25:c25:2005:928f
422c19:dd:d9:dd:c25:c25:2005:9290/1242c19:dd:d9:dd:c25:c25:2005:929f
432c19:dd:d9:dd:c25:c25:2005:92a0/1242c19:dd:d9:dd:c25:c25:2005:92af
442c19:dd:d9:dd:c25:c25:2005:92b0/1242c19:dd:d9:dd:c25:c25:2005:92bf
452c19:dd:d9:dd:c25:c25:2005:92c0/1242c19:dd:d9:dd:c25:c25:2005:92cf
462c19:dd:d9:dd:c25:c25:2005:92d0/1242c19:dd:d9:dd:c25:c25:2005:92df
472c19:dd:d9:dd:c25:c25:2005:92e0/1242c19:dd:d9:dd:c25:c25:2005:92ef
482c19:dd:d9:dd:c25:c25:2005:92f0/1242c19:dd:d9:dd:c25:c25:2005:92ff
492c19:dd:d9:dd:c25:c25:2005:9300/1242c19:dd:d9:dd:c25:c25:2005:930f
502c19:dd:d9:dd:c25:c25:2005:9310/1242c19:dd:d9:dd:c25:c25:2005:931f
512c19:dd:d9:dd:c25:c25:2005:9320/1242c19:dd:d9:dd:c25:c25:2005:932f
522c19:dd:d9:dd:c25:c25:2005:9330/1242c19:dd:d9:dd:c25:c25:2005:933f
532c19:dd:d9:dd:c25:c25:2005:9340/1242c19:dd:d9:dd:c25:c25:2005:934f
542c19:dd:d9:dd:c25:c25:2005:9350/1242c19:dd:d9:dd:c25:c25:2005:935f
552c19:dd:d9:dd:c25:c25:2005:9360/1242c19:dd:d9:dd:c25:c25:2005:936f
562c19:dd:d9:dd:c25:c25:2005:9370/1242c19:dd:d9:dd:c25:c25:2005:937f
572c19:dd:d9:dd:c25:c25:2005:9380/1242c19:dd:d9:dd:c25:c25:2005:938f
582c19:dd:d9:dd:c25:c25:2005:9390/1242c19:dd:d9:dd:c25:c25:2005:939f
592c19:dd:d9:dd:c25:c25:2005:93a0/1242c19:dd:d9:dd:c25:c25:2005:93af
602c19:dd:d9:dd:c25:c25:2005:93b0/1242c19:dd:d9:dd:c25:c25:2005:93bf
612c19:dd:d9:dd:c25:c25:2005:93c0/1242c19:dd:d9:dd:c25:c25:2005:93cf
622c19:dd:d9:dd:c25:c25:2005:93d0/1242c19:dd:d9:dd:c25:c25:2005:93df
632c19:dd:d9:dd:c25:c25:2005:93e0/1242c19:dd:d9:dd:c25:c25:2005:93ef
642c19:dd:d9:dd:c25:c25:2005:93f0/1242c19:dd:d9:dd:c25:c25:2005:93ff
652c19:dd:d9:dd:c25:c25:2005:9400/1242c19:dd:d9:dd:c25:c25:2005:940f
662c19:dd:d9:dd:c25:c25:2005:9410/1242c19:dd:d9:dd:c25:c25:2005:941f
672c19:dd:d9:dd:c25:c25:2005:9420/1242c19:dd:d9:dd:c25:c25:2005:942f
682c19:dd:d9:dd:c25:c25:2005:9430/1242c19:dd:d9:dd:c25:c25:2005:943f
692c19:dd:d9:dd:c25:c25:2005:9440/1242c19:dd:d9:dd:c25:c25:2005:944f
702c19:dd:d9:dd:c25:c25:2005:9450/1242c19:dd:d9:dd:c25:c25:2005:945f
712c19:dd:d9:dd:c25:c25:2005:9460/1242c19:dd:d9:dd:c25:c25:2005:946f
722c19:dd:d9:dd:c25:c25:2005:9470/1242c19:dd:d9:dd:c25:c25:2005:947f
732c19:dd:d9:dd:c25:c25:2005:9480/1242c19:dd:d9:dd:c25:c25:2005:948f
742c19:dd:d9:dd:c25:c25:2005:9490/1242c19:dd:d9:dd:c25:c25:2005:949f
752c19:dd:d9:dd:c25:c25:2005:94a0/1242c19:dd:d9:dd:c25:c25:2005:94af
762c19:dd:d9:dd:c25:c25:2005:94b0/1242c19:dd:d9:dd:c25:c25:2005:94bf
772c19:dd:d9:dd:c25:c25:2005:94c0/1242c19:dd:d9:dd:c25:c25:2005:94cf
782c19:dd:d9:dd:c25:c25:2005:94d0/1242c19:dd:d9:dd:c25:c25:2005:94df
792c19:dd:d9:dd:c25:c25:2005:94e0/1242c19:dd:d9:dd:c25:c25:2005:94ef
802c19:dd:d9:dd:c25:c25:2005:94f0/1242c19:dd:d9:dd:c25:c25:2005:94ff
812c19:dd:d9:dd:c25:c25:2005:9500/1242c19:dd:d9:dd:c25:c25:2005:950f
822c19:dd:d9:dd:c25:c25:2005:9510/1242c19:dd:d9:dd:c25:c25:2005:951f
832c19:dd:d9:dd:c25:c25:2005:9520/1242c19:dd:d9:dd:c25:c25:2005:952f
842c19:dd:d9:dd:c25:c25:2005:9530/1242c19:dd:d9:dd:c25:c25:2005:953f
852c19:dd:d9:dd:c25:c25:2005:9540/1242c19:dd:d9:dd:c25:c25:2005:954f
862c19:dd:d9:dd:c25:c25:2005:9550/1242c19:dd:d9:dd:c25:c25:2005:955f
872c19:dd:d9:dd:c25:c25:2005:9560/1242c19:dd:d9:dd:c25:c25:2005:956f
882c19:dd:d9:dd:c25:c25:2005:9570/1242c19:dd:d9:dd:c25:c25:2005:957f
892c19:dd:d9:dd:c25:c25:2005:9580/1242c19:dd:d9:dd:c25:c25:2005:958f
902c19:dd:d9:dd:c25:c25:2005:9590/1242c19:dd:d9:dd:c25:c25:2005:959f
912c19:dd:d9:dd:c25:c25:2005:95a0/1242c19:dd:d9:dd:c25:c25:2005:95af
922c19:dd:d9:dd:c25:c25:2005:95b0/1242c19:dd:d9:dd:c25:c25:2005:95bf
932c19:dd:d9:dd:c25:c25:2005:95c0/1242c19:dd:d9:dd:c25:c25:2005:95cf
942c19:dd:d9:dd:c25:c25:2005:95d0/1242c19:dd:d9:dd:c25:c25:2005:95df
952c19:dd:d9:dd:c25:c25:2005:95e0/1242c19:dd:d9:dd:c25:c25:2005:95ef
962c19:dd:d9:dd:c25:c25:2005:95f0/1242c19:dd:d9:dd:c25:c25:2005:95ff
972c19:dd:d9:dd:c25:c25:2005:9600/1242c19:dd:d9:dd:c25:c25:2005:960f
982c19:dd:d9:dd:c25:c25:2005:9610/1242c19:dd:d9:dd:c25:c25:2005:961f
992c19:dd:d9:dd:c25:c25:2005:9620/1242c19:dd:d9:dd:c25:c25:2005:962f
1002c19:dd:d9:dd:c25:c25:2005:9630/1242c19:dd:d9:dd:c25:c25:2005:963f
1012c19:dd:d9:dd:c25:c25:2005:9640/1242c19:dd:d9:dd:c25:c25:2005:964f
1022c19:dd:d9:dd:c25:c25:2005:9650/1242c19:dd:d9:dd:c25:c25:2005:965f
1032c19:dd:d9:dd:c25:c25:2005:9660/1242c19:dd:d9:dd:c25:c25:2005:966f
1042c19:dd:d9:dd:c25:c25:2005:9670/1242c19:dd:d9:dd:c25:c25:2005:967f
1052c19:dd:d9:dd:c25:c25:2005:9680/1242c19:dd:d9:dd:c25:c25:2005:968f
1062c19:dd:d9:dd:c25:c25:2005:9690/1242c19:dd:d9:dd:c25:c25:2005:969f
1072c19:dd:d9:dd:c25:c25:2005:96a0/1242c19:dd:d9:dd:c25:c25:2005:96af
1082c19:dd:d9:dd:c25:c25:2005:96b0/1242c19:dd:d9:dd:c25:c25:2005:96bf
1092c19:dd:d9:dd:c25:c25:2005:96c0/1242c19:dd:d9:dd:c25:c25:2005:96cf
1102c19:dd:d9:dd:c25:c25:2005:96d0/1242c19:dd:d9:dd:c25:c25:2005:96df
1112c19:dd:d9:dd:c25:c25:2005:96e0/1242c19:dd:d9:dd:c25:c25:2005:96ef
1122c19:dd:d9:dd:c25:c25:2005:96f0/1242c19:dd:d9:dd:c25:c25:2005:96ff
1132c19:dd:d9:dd:c25:c25:2005:9700/1242c19:dd:d9:dd:c25:c25:2005:970f
1142c19:dd:d9:dd:c25:c25:2005:9710/1242c19:dd:d9:dd:c25:c25:2005:971f
1152c19:dd:d9:dd:c25:c25:2005:9720/1242c19:dd:d9:dd:c25:c25:2005:972f
1162c19:dd:d9:dd:c25:c25:2005:9730/1242c19:dd:d9:dd:c25:c25:2005:973f
1172c19:dd:d9:dd:c25:c25:2005:9740/1242c19:dd:d9:dd:c25:c25:2005:974f
1182c19:dd:d9:dd:c25:c25:2005:9750/1242c19:dd:d9:dd:c25:c25:2005:975f
1192c19:dd:d9:dd:c25:c25:2005:9760/1242c19:dd:d9:dd:c25:c25:2005:976f
1202c19:dd:d9:dd:c25:c25:2005:9770/1242c19:dd:d9:dd:c25:c25:2005:977f
1212c19:dd:d9:dd:c25:c25:2005:9780/1242c19:dd:d9:dd:c25:c25:2005:978f
1222c19:dd:d9:dd:c25:c25:2005:9790/1242c19:dd:d9:dd:c25:c25:2005:979f
1232c19:dd:d9:dd:c25:c25:2005:97a0/1242c19:dd:d9:dd:c25:c25:2005:97af
1242c19:dd:d9:dd:c25:c25:2005:97b0/1242c19:dd:d9:dd:c25:c25:2005:97bf
1252c19:dd:d9:dd:c25:c25:2005:97c0/1242c19:dd:d9:dd:c25:c25:2005:97cf
1262c19:dd:d9:dd:c25:c25:2005:97d0/1242c19:dd:d9:dd:c25:c25:2005:97df
1272c19:dd:d9:dd:c25:c25:2005:97e0/1242c19:dd:d9:dd:c25:c25:2005:97ef
1282c19:dd:d9:dd:c25:c25:2005:97f0/1242c19:dd:d9:dd:c25:c25:2005:97ff
1292c19:dd:d9:dd:c25:c25:2005:9800/1242c19:dd:d9:dd:c25:c25:2005:980f
1302c19:dd:d9:dd:c25:c25:2005:9810/1242c19:dd:d9:dd:c25:c25:2005:981f
1312c19:dd:d9:dd:c25:c25:2005:9820/1242c19:dd:d9:dd:c25:c25:2005:982f
1322c19:dd:d9:dd:c25:c25:2005:9830/1242c19:dd:d9:dd:c25:c25:2005:983f
1332c19:dd:d9:dd:c25:c25:2005:9840/1242c19:dd:d9:dd:c25:c25:2005:984f
1342c19:dd:d9:dd:c25:c25:2005:9850/1242c19:dd:d9:dd:c25:c25:2005:985f
1352c19:dd:d9:dd:c25:c25:2005:9860/1242c19:dd:d9:dd:c25:c25:2005:986f
1362c19:dd:d9:dd:c25:c25:2005:9870/1242c19:dd:d9:dd:c25:c25:2005:987f
1372c19:dd:d9:dd:c25:c25:2005:9880/1242c19:dd:d9:dd:c25:c25:2005:988f
1382c19:dd:d9:dd:c25:c25:2005:9890/1242c19:dd:d9:dd:c25:c25:2005:989f
1392c19:dd:d9:dd:c25:c25:2005:98a0/1242c19:dd:d9:dd:c25:c25:2005:98af
1402c19:dd:d9:dd:c25:c25:2005:98b0/1242c19:dd:d9:dd:c25:c25:2005:98bf
1412c19:dd:d9:dd:c25:c25:2005:98c0/1242c19:dd:d9:dd:c25:c25:2005:98cf
1422c19:dd:d9:dd:c25:c25:2005:98d0/1242c19:dd:d9:dd:c25:c25:2005:98df
1432c19:dd:d9:dd:c25:c25:2005:98e0/1242c19:dd:d9:dd:c25:c25:2005:98ef
1442c19:dd:d9:dd:c25:c25:2005:98f0/1242c19:dd:d9:dd:c25:c25:2005:98ff
1452c19:dd:d9:dd:c25:c25:2005:9900/1242c19:dd:d9:dd:c25:c25:2005:990f
1462c19:dd:d9:dd:c25:c25:2005:9910/1242c19:dd:d9:dd:c25:c25:2005:991f
1472c19:dd:d9:dd:c25:c25:2005:9920/1242c19:dd:d9:dd:c25:c25:2005:992f
1482c19:dd:d9:dd:c25:c25:2005:9930/1242c19:dd:d9:dd:c25:c25:2005:993f
1492c19:dd:d9:dd:c25:c25:2005:9940/1242c19:dd:d9:dd:c25:c25:2005:994f
1502c19:dd:d9:dd:c25:c25:2005:9950/1242c19:dd:d9:dd:c25:c25:2005:995f
1512c19:dd:d9:dd:c25:c25:2005:9960/1242c19:dd:d9:dd:c25:c25:2005:996f
1522c19:dd:d9:dd:c25:c25:2005:9970/1242c19:dd:d9:dd:c25:c25:2005:997f
1532c19:dd:d9:dd:c25:c25:2005:9980/1242c19:dd:d9:dd:c25:c25:2005:998f
1542c19:dd:d9:dd:c25:c25:2005:9990/1242c19:dd:d9:dd:c25:c25:2005:999f
1552c19:dd:d9:dd:c25:c25:2005:99a0/1242c19:dd:d9:dd:c25:c25:2005:99af
1562c19:dd:d9:dd:c25:c25:2005:99b0/1242c19:dd:d9:dd:c25:c25:2005:99bf
1572c19:dd:d9:dd:c25:c25:2005:99c0/1242c19:dd:d9:dd:c25:c25:2005:99cf
1582c19:dd:d9:dd:c25:c25:2005:99d0/1242c19:dd:d9:dd:c25:c25:2005:99df
1592c19:dd:d9:dd:c25:c25:2005:99e0/1242c19:dd:d9:dd:c25:c25:2005:99ef
1602c19:dd:d9:dd:c25:c25:2005:99f0/1242c19:dd:d9:dd:c25:c25:2005:99ff
1612c19:dd:d9:dd:c25:c25:2005:9a00/1242c19:dd:d9:dd:c25:c25:2005:9a0f
1622c19:dd:d9:dd:c25:c25:2005:9a10/1242c19:dd:d9:dd:c25:c25:2005:9a1f
1632c19:dd:d9:dd:c25:c25:2005:9a20/1242c19:dd:d9:dd:c25:c25:2005:9a2f
1642c19:dd:d9:dd:c25:c25:2005:9a30/1242c19:dd:d9:dd:c25:c25:2005:9a3f
1652c19:dd:d9:dd:c25:c25:2005:9a40/1242c19:dd:d9:dd:c25:c25:2005:9a4f
1662c19:dd:d9:dd:c25:c25:2005:9a50/1242c19:dd:d9:dd:c25:c25:2005:9a5f
1672c19:dd:d9:dd:c25:c25:2005:9a60/1242c19:dd:d9:dd:c25:c25:2005:9a6f
1682c19:dd:d9:dd:c25:c25:2005:9a70/1242c19:dd:d9:dd:c25:c25:2005:9a7f
1692c19:dd:d9:dd:c25:c25:2005:9a80/1242c19:dd:d9:dd:c25:c25:2005:9a8f
1702c19:dd:d9:dd:c25:c25:2005:9a90/1242c19:dd:d9:dd:c25:c25:2005:9a9f
1712c19:dd:d9:dd:c25:c25:2005:9aa0/1242c19:dd:d9:dd:c25:c25:2005:9aaf
1722c19:dd:d9:dd:c25:c25:2005:9ab0/1242c19:dd:d9:dd:c25:c25:2005:9abf
1732c19:dd:d9:dd:c25:c25:2005:9ac0/1242c19:dd:d9:dd:c25:c25:2005:9acf
1742c19:dd:d9:dd:c25:c25:2005:9ad0/1242c19:dd:d9:dd:c25:c25:2005:9adf
1752c19:dd:d9:dd:c25:c25:2005:9ae0/1242c19:dd:d9:dd:c25:c25:2005:9aef
1762c19:dd:d9:dd:c25:c25:2005:9af0/1242c19:dd:d9:dd:c25:c25:2005:9aff
1772c19:dd:d9:dd:c25:c25:2005:9b00/1242c19:dd:d9:dd:c25:c25:2005:9b0f
1782c19:dd:d9:dd:c25:c25:2005:9b10/1242c19:dd:d9:dd:c25:c25:2005:9b1f
1792c19:dd:d9:dd:c25:c25:2005:9b20/1242c19:dd:d9:dd:c25:c25:2005:9b2f
1802c19:dd:d9:dd:c25:c25:2005:9b30/1242c19:dd:d9:dd:c25:c25:2005:9b3f
1812c19:dd:d9:dd:c25:c25:2005:9b40/1242c19:dd:d9:dd:c25:c25:2005:9b4f
1822c19:dd:d9:dd:c25:c25:2005:9b50/1242c19:dd:d9:dd:c25:c25:2005:9b5f
1832c19:dd:d9:dd:c25:c25:2005:9b60/1242c19:dd:d9:dd:c25:c25:2005:9b6f
1842c19:dd:d9:dd:c25:c25:2005:9b70/1242c19:dd:d9:dd:c25:c25:2005:9b7f
1852c19:dd:d9:dd:c25:c25:2005:9b80/1242c19:dd:d9:dd:c25:c25:2005:9b8f
1862c19:dd:d9:dd:c25:c25:2005:9b90/1242c19:dd:d9:dd:c25:c25:2005:9b9f
1872c19:dd:d9:dd:c25:c25:2005:9ba0/1242c19:dd:d9:dd:c25:c25:2005:9baf
1882c19:dd:d9:dd:c25:c25:2005:9bb0/1242c19:dd:d9:dd:c25:c25:2005:9bbf
1892c19:dd:d9:dd:c25:c25:2005:9bc0/1242c19:dd:d9:dd:c25:c25:2005:9bcf
1902c19:dd:d9:dd:c25:c25:2005:9bd0/1242c19:dd:d9:dd:c25:c25:2005:9bdf
1912c19:dd:d9:dd:c25:c25:2005:9be0/1242c19:dd:d9:dd:c25:c25:2005:9bef
1922c19:dd:d9:dd:c25:c25:2005:9bf0/1242c19:dd:d9:dd:c25:c25:2005:9bff
1932c19:dd:d9:dd:c25:c25:2005:9c00/1242c19:dd:d9:dd:c25:c25:2005:9c0f
1942c19:dd:d9:dd:c25:c25:2005:9c10/1242c19:dd:d9:dd:c25:c25:2005:9c1f
1952c19:dd:d9:dd:c25:c25:2005:9c20/1242c19:dd:d9:dd:c25:c25:2005:9c2f
1962c19:dd:d9:dd:c25:c25:2005:9c30/1242c19:dd:d9:dd:c25:c25:2005:9c3f
1972c19:dd:d9:dd:c25:c25:2005:9c40/1242c19:dd:d9:dd:c25:c25:2005:9c4f
1982c19:dd:d9:dd:c25:c25:2005:9c50/1242c19:dd:d9:dd:c25:c25:2005:9c5f
1992c19:dd:d9:dd:c25:c25:2005:9c60/1242c19:dd:d9:dd:c25:c25:2005:9c6f
2002c19:dd:d9:dd:c25:c25:2005:9c70/1242c19:dd:d9:dd:c25:c25:2005:9c7f
2012c19:dd:d9:dd:c25:c25:2005:9c80/1242c19:dd:d9:dd:c25:c25:2005:9c8f
2022c19:dd:d9:dd:c25:c25:2005:9c90/1242c19:dd:d9:dd:c25:c25:2005:9c9f
2032c19:dd:d9:dd:c25:c25:2005:9ca0/1242c19:dd:d9:dd:c25:c25:2005:9caf
2042c19:dd:d9:dd:c25:c25:2005:9cb0/1242c19:dd:d9:dd:c25:c25:2005:9cbf
2052c19:dd:d9:dd:c25:c25:2005:9cc0/1242c19:dd:d9:dd:c25:c25:2005:9ccf
2062c19:dd:d9:dd:c25:c25:2005:9cd0/1242c19:dd:d9:dd:c25:c25:2005:9cdf
2072c19:dd:d9:dd:c25:c25:2005:9ce0/1242c19:dd:d9:dd:c25:c25:2005:9cef
2082c19:dd:d9:dd:c25:c25:2005:9cf0/1242c19:dd:d9:dd:c25:c25:2005:9cff
2092c19:dd:d9:dd:c25:c25:2005:9d00/1242c19:dd:d9:dd:c25:c25:2005:9d0f
2102c19:dd:d9:dd:c25:c25:2005:9d10/1242c19:dd:d9:dd:c25:c25:2005:9d1f
2112c19:dd:d9:dd:c25:c25:2005:9d20/1242c19:dd:d9:dd:c25:c25:2005:9d2f
2122c19:dd:d9:dd:c25:c25:2005:9d30/1242c19:dd:d9:dd:c25:c25:2005:9d3f
2132c19:dd:d9:dd:c25:c25:2005:9d40/1242c19:dd:d9:dd:c25:c25:2005:9d4f
2142c19:dd:d9:dd:c25:c25:2005:9d50/1242c19:dd:d9:dd:c25:c25:2005:9d5f
2152c19:dd:d9:dd:c25:c25:2005:9d60/1242c19:dd:d9:dd:c25:c25:2005:9d6f
2162c19:dd:d9:dd:c25:c25:2005:9d70/1242c19:dd:d9:dd:c25:c25:2005:9d7f
2172c19:dd:d9:dd:c25:c25:2005:9d80/1242c19:dd:d9:dd:c25:c25:2005:9d8f
2182c19:dd:d9:dd:c25:c25:2005:9d90/1242c19:dd:d9:dd:c25:c25:2005:9d9f
2192c19:dd:d9:dd:c25:c25:2005:9da0/1242c19:dd:d9:dd:c25:c25:2005:9daf
2202c19:dd:d9:dd:c25:c25:2005:9db0/1242c19:dd:d9:dd:c25:c25:2005:9dbf
2212c19:dd:d9:dd:c25:c25:2005:9dc0/1242c19:dd:d9:dd:c25:c25:2005:9dcf
2222c19:dd:d9:dd:c25:c25:2005:9dd0/1242c19:dd:d9:dd:c25:c25:2005:9ddf
2232c19:dd:d9:dd:c25:c25:2005:9de0/1242c19:dd:d9:dd:c25:c25:2005:9def
2242c19:dd:d9:dd:c25:c25:2005:9df0/1242c19:dd:d9:dd:c25:c25:2005:9dff
2252c19:dd:d9:dd:c25:c25:2005:9e00/1242c19:dd:d9:dd:c25:c25:2005:9e0f
2262c19:dd:d9:dd:c25:c25:2005:9e10/1242c19:dd:d9:dd:c25:c25:2005:9e1f
2272c19:dd:d9:dd:c25:c25:2005:9e20/1242c19:dd:d9:dd:c25:c25:2005:9e2f
2282c19:dd:d9:dd:c25:c25:2005:9e30/1242c19:dd:d9:dd:c25:c25:2005:9e3f
2292c19:dd:d9:dd:c25:c25:2005:9e40/1242c19:dd:d9:dd:c25:c25:2005:9e4f
2302c19:dd:d9:dd:c25:c25:2005:9e50/1242c19:dd:d9:dd:c25:c25:2005:9e5f
2312c19:dd:d9:dd:c25:c25:2005:9e60/1242c19:dd:d9:dd:c25:c25:2005:9e6f
2322c19:dd:d9:dd:c25:c25:2005:9e70/1242c19:dd:d9:dd:c25:c25:2005:9e7f
2332c19:dd:d9:dd:c25:c25:2005:9e80/1242c19:dd:d9:dd:c25:c25:2005:9e8f
2342c19:dd:d9:dd:c25:c25:2005:9e90/1242c19:dd:d9:dd:c25:c25:2005:9e9f
2352c19:dd:d9:dd:c25:c25:2005:9ea0/1242c19:dd:d9:dd:c25:c25:2005:9eaf
2362c19:dd:d9:dd:c25:c25:2005:9eb0/1242c19:dd:d9:dd:c25:c25:2005:9ebf
2372c19:dd:d9:dd:c25:c25:2005:9ec0/1242c19:dd:d9:dd:c25:c25:2005:9ecf
2382c19:dd:d9:dd:c25:c25:2005:9ed0/1242c19:dd:d9:dd:c25:c25:2005:9edf
2392c19:dd:d9:dd:c25:c25:2005:9ee0/1242c19:dd:d9:dd:c25:c25:2005:9eef
2402c19:dd:d9:dd:c25:c25:2005:9ef0/1242c19:dd:d9:dd:c25:c25:2005:9eff
2412c19:dd:d9:dd:c25:c25:2005:9f00/1242c19:dd:d9:dd:c25:c25:2005:9f0f
2422c19:dd:d9:dd:c25:c25:2005:9f10/1242c19:dd:d9:dd:c25:c25:2005:9f1f
2432c19:dd:d9:dd:c25:c25:2005:9f20/1242c19:dd:d9:dd:c25:c25:2005:9f2f
2442c19:dd:d9:dd:c25:c25:2005:9f30/1242c19:dd:d9:dd:c25:c25:2005:9f3f
2452c19:dd:d9:dd:c25:c25:2005:9f40/1242c19:dd:d9:dd:c25:c25:2005:9f4f
2462c19:dd:d9:dd:c25:c25:2005:9f50/1242c19:dd:d9:dd:c25:c25:2005:9f5f
2472c19:dd:d9:dd:c25:c25:2005:9f60/1242c19:dd:d9:dd:c25:c25:2005:9f6f
2482c19:dd:d9:dd:c25:c25:2005:9f70/1242c19:dd:d9:dd:c25:c25:2005:9f7f
2492c19:dd:d9:dd:c25:c25:2005:9f80/1242c19:dd:d9:dd:c25:c25:2005:9f8f
2502c19:dd:d9:dd:c25:c25:2005:9f90/1242c19:dd:d9:dd:c25:c25:2005:9f9f
2512c19:dd:d9:dd:c25:c25:2005:9fa0/1242c19:dd:d9:dd:c25:c25:2005:9faf
2522c19:dd:d9:dd:c25:c25:2005:9fb0/1242c19:dd:d9:dd:c25:c25:2005:9fbf
2532c19:dd:d9:dd:c25:c25:2005:9fc0/1242c19:dd:d9:dd:c25:c25:2005:9fcf
2542c19:dd:d9:dd:c25:c25:2005:9fd0/1242c19:dd:d9:dd:c25:c25:2005:9fdf
2552c19:dd:d9:dd:c25:c25:2005:9fe0/1242c19:dd:d9:dd:c25:c25:2005:9fef
2562c19:dd:d9:dd:c25:c25:2005:9ff0/1242c19:dd:d9:dd:c25:c25:2005:9fff

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.