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/119
Addresses512
/64 networksPart of one
Network
2c19:dd:d9:dd:c25:c25:d915:bc00/119
First address
2c19:dd:d9:dd:c25:c25:d915:bc00
Last address
2c19:dd:d9:dd:c25:c25:d915:bdff
Addresses
512
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:d915:bc00
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
c.b.5.1.9.d.5.2.c.0.5.2.c.0.d.d.0.0.9.d.0.0.d.d.0.0.9.1.c.2.ip6.arpa
d.b.5.1.9.d.5.2.c.0.5.2.c.0.d.d.0.0.9.d.0.0.d.d.0.0.9.1.c.2.ip6.arpa
/119 is not on a 4-bit boundary, so it takes 2 /120 zones.
Split into smaller subnets/127
/120 (2)/121 (4)/122 (8)/123 (16)/124 (32)/127 (256)/128 (512)

2c19:dd:d9:dd:c25:c25:d915:bc00/119 makes 256 subnets of /127.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:d915:bc00/1272c19:dd:d9:dd:c25:c25:d915:bc01
22c19:dd:d9:dd:c25:c25:d915:bc02/1272c19:dd:d9:dd:c25:c25:d915:bc03
32c19:dd:d9:dd:c25:c25:d915:bc04/1272c19:dd:d9:dd:c25:c25:d915:bc05
42c19:dd:d9:dd:c25:c25:d915:bc06/1272c19:dd:d9:dd:c25:c25:d915:bc07
52c19:dd:d9:dd:c25:c25:d915:bc08/1272c19:dd:d9:dd:c25:c25:d915:bc09
62c19:dd:d9:dd:c25:c25:d915:bc0a/1272c19:dd:d9:dd:c25:c25:d915:bc0b
72c19:dd:d9:dd:c25:c25:d915:bc0c/1272c19:dd:d9:dd:c25:c25:d915:bc0d
82c19:dd:d9:dd:c25:c25:d915:bc0e/1272c19:dd:d9:dd:c25:c25:d915:bc0f
92c19:dd:d9:dd:c25:c25:d915:bc10/1272c19:dd:d9:dd:c25:c25:d915:bc11
102c19:dd:d9:dd:c25:c25:d915:bc12/1272c19:dd:d9:dd:c25:c25:d915:bc13
112c19:dd:d9:dd:c25:c25:d915:bc14/1272c19:dd:d9:dd:c25:c25:d915:bc15
122c19:dd:d9:dd:c25:c25:d915:bc16/1272c19:dd:d9:dd:c25:c25:d915:bc17
132c19:dd:d9:dd:c25:c25:d915:bc18/1272c19:dd:d9:dd:c25:c25:d915:bc19
142c19:dd:d9:dd:c25:c25:d915:bc1a/1272c19:dd:d9:dd:c25:c25:d915:bc1b
152c19:dd:d9:dd:c25:c25:d915:bc1c/1272c19:dd:d9:dd:c25:c25:d915:bc1d
162c19:dd:d9:dd:c25:c25:d915:bc1e/1272c19:dd:d9:dd:c25:c25:d915:bc1f
172c19:dd:d9:dd:c25:c25:d915:bc20/1272c19:dd:d9:dd:c25:c25:d915:bc21
182c19:dd:d9:dd:c25:c25:d915:bc22/1272c19:dd:d9:dd:c25:c25:d915:bc23
192c19:dd:d9:dd:c25:c25:d915:bc24/1272c19:dd:d9:dd:c25:c25:d915:bc25
202c19:dd:d9:dd:c25:c25:d915:bc26/1272c19:dd:d9:dd:c25:c25:d915:bc27
212c19:dd:d9:dd:c25:c25:d915:bc28/1272c19:dd:d9:dd:c25:c25:d915:bc29
222c19:dd:d9:dd:c25:c25:d915:bc2a/1272c19:dd:d9:dd:c25:c25:d915:bc2b
232c19:dd:d9:dd:c25:c25:d915:bc2c/1272c19:dd:d9:dd:c25:c25:d915:bc2d
242c19:dd:d9:dd:c25:c25:d915:bc2e/1272c19:dd:d9:dd:c25:c25:d915:bc2f
252c19:dd:d9:dd:c25:c25:d915:bc30/1272c19:dd:d9:dd:c25:c25:d915:bc31
262c19:dd:d9:dd:c25:c25:d915:bc32/1272c19:dd:d9:dd:c25:c25:d915:bc33
272c19:dd:d9:dd:c25:c25:d915:bc34/1272c19:dd:d9:dd:c25:c25:d915:bc35
282c19:dd:d9:dd:c25:c25:d915:bc36/1272c19:dd:d9:dd:c25:c25:d915:bc37
292c19:dd:d9:dd:c25:c25:d915:bc38/1272c19:dd:d9:dd:c25:c25:d915:bc39
302c19:dd:d9:dd:c25:c25:d915:bc3a/1272c19:dd:d9:dd:c25:c25:d915:bc3b
312c19:dd:d9:dd:c25:c25:d915:bc3c/1272c19:dd:d9:dd:c25:c25:d915:bc3d
322c19:dd:d9:dd:c25:c25:d915:bc3e/1272c19:dd:d9:dd:c25:c25:d915:bc3f
332c19:dd:d9:dd:c25:c25:d915:bc40/1272c19:dd:d9:dd:c25:c25:d915:bc41
342c19:dd:d9:dd:c25:c25:d915:bc42/1272c19:dd:d9:dd:c25:c25:d915:bc43
352c19:dd:d9:dd:c25:c25:d915:bc44/1272c19:dd:d9:dd:c25:c25:d915:bc45
362c19:dd:d9:dd:c25:c25:d915:bc46/1272c19:dd:d9:dd:c25:c25:d915:bc47
372c19:dd:d9:dd:c25:c25:d915:bc48/1272c19:dd:d9:dd:c25:c25:d915:bc49
382c19:dd:d9:dd:c25:c25:d915:bc4a/1272c19:dd:d9:dd:c25:c25:d915:bc4b
392c19:dd:d9:dd:c25:c25:d915:bc4c/1272c19:dd:d9:dd:c25:c25:d915:bc4d
402c19:dd:d9:dd:c25:c25:d915:bc4e/1272c19:dd:d9:dd:c25:c25:d915:bc4f
412c19:dd:d9:dd:c25:c25:d915:bc50/1272c19:dd:d9:dd:c25:c25:d915:bc51
422c19:dd:d9:dd:c25:c25:d915:bc52/1272c19:dd:d9:dd:c25:c25:d915:bc53
432c19:dd:d9:dd:c25:c25:d915:bc54/1272c19:dd:d9:dd:c25:c25:d915:bc55
442c19:dd:d9:dd:c25:c25:d915:bc56/1272c19:dd:d9:dd:c25:c25:d915:bc57
452c19:dd:d9:dd:c25:c25:d915:bc58/1272c19:dd:d9:dd:c25:c25:d915:bc59
462c19:dd:d9:dd:c25:c25:d915:bc5a/1272c19:dd:d9:dd:c25:c25:d915:bc5b
472c19:dd:d9:dd:c25:c25:d915:bc5c/1272c19:dd:d9:dd:c25:c25:d915:bc5d
482c19:dd:d9:dd:c25:c25:d915:bc5e/1272c19:dd:d9:dd:c25:c25:d915:bc5f
492c19:dd:d9:dd:c25:c25:d915:bc60/1272c19:dd:d9:dd:c25:c25:d915:bc61
502c19:dd:d9:dd:c25:c25:d915:bc62/1272c19:dd:d9:dd:c25:c25:d915:bc63
512c19:dd:d9:dd:c25:c25:d915:bc64/1272c19:dd:d9:dd:c25:c25:d915:bc65
522c19:dd:d9:dd:c25:c25:d915:bc66/1272c19:dd:d9:dd:c25:c25:d915:bc67
532c19:dd:d9:dd:c25:c25:d915:bc68/1272c19:dd:d9:dd:c25:c25:d915:bc69
542c19:dd:d9:dd:c25:c25:d915:bc6a/1272c19:dd:d9:dd:c25:c25:d915:bc6b
552c19:dd:d9:dd:c25:c25:d915:bc6c/1272c19:dd:d9:dd:c25:c25:d915:bc6d
562c19:dd:d9:dd:c25:c25:d915:bc6e/1272c19:dd:d9:dd:c25:c25:d915:bc6f
572c19:dd:d9:dd:c25:c25:d915:bc70/1272c19:dd:d9:dd:c25:c25:d915:bc71
582c19:dd:d9:dd:c25:c25:d915:bc72/1272c19:dd:d9:dd:c25:c25:d915:bc73
592c19:dd:d9:dd:c25:c25:d915:bc74/1272c19:dd:d9:dd:c25:c25:d915:bc75
602c19:dd:d9:dd:c25:c25:d915:bc76/1272c19:dd:d9:dd:c25:c25:d915:bc77
612c19:dd:d9:dd:c25:c25:d915:bc78/1272c19:dd:d9:dd:c25:c25:d915:bc79
622c19:dd:d9:dd:c25:c25:d915:bc7a/1272c19:dd:d9:dd:c25:c25:d915:bc7b
632c19:dd:d9:dd:c25:c25:d915:bc7c/1272c19:dd:d9:dd:c25:c25:d915:bc7d
642c19:dd:d9:dd:c25:c25:d915:bc7e/1272c19:dd:d9:dd:c25:c25:d915:bc7f
652c19:dd:d9:dd:c25:c25:d915:bc80/1272c19:dd:d9:dd:c25:c25:d915:bc81
662c19:dd:d9:dd:c25:c25:d915:bc82/1272c19:dd:d9:dd:c25:c25:d915:bc83
672c19:dd:d9:dd:c25:c25:d915:bc84/1272c19:dd:d9:dd:c25:c25:d915:bc85
682c19:dd:d9:dd:c25:c25:d915:bc86/1272c19:dd:d9:dd:c25:c25:d915:bc87
692c19:dd:d9:dd:c25:c25:d915:bc88/1272c19:dd:d9:dd:c25:c25:d915:bc89
702c19:dd:d9:dd:c25:c25:d915:bc8a/1272c19:dd:d9:dd:c25:c25:d915:bc8b
712c19:dd:d9:dd:c25:c25:d915:bc8c/1272c19:dd:d9:dd:c25:c25:d915:bc8d
722c19:dd:d9:dd:c25:c25:d915:bc8e/1272c19:dd:d9:dd:c25:c25:d915:bc8f
732c19:dd:d9:dd:c25:c25:d915:bc90/1272c19:dd:d9:dd:c25:c25:d915:bc91
742c19:dd:d9:dd:c25:c25:d915:bc92/1272c19:dd:d9:dd:c25:c25:d915:bc93
752c19:dd:d9:dd:c25:c25:d915:bc94/1272c19:dd:d9:dd:c25:c25:d915:bc95
762c19:dd:d9:dd:c25:c25:d915:bc96/1272c19:dd:d9:dd:c25:c25:d915:bc97
772c19:dd:d9:dd:c25:c25:d915:bc98/1272c19:dd:d9:dd:c25:c25:d915:bc99
782c19:dd:d9:dd:c25:c25:d915:bc9a/1272c19:dd:d9:dd:c25:c25:d915:bc9b
792c19:dd:d9:dd:c25:c25:d915:bc9c/1272c19:dd:d9:dd:c25:c25:d915:bc9d
802c19:dd:d9:dd:c25:c25:d915:bc9e/1272c19:dd:d9:dd:c25:c25:d915:bc9f
812c19:dd:d9:dd:c25:c25:d915:bca0/1272c19:dd:d9:dd:c25:c25:d915:bca1
822c19:dd:d9:dd:c25:c25:d915:bca2/1272c19:dd:d9:dd:c25:c25:d915:bca3
832c19:dd:d9:dd:c25:c25:d915:bca4/1272c19:dd:d9:dd:c25:c25:d915:bca5
842c19:dd:d9:dd:c25:c25:d915:bca6/1272c19:dd:d9:dd:c25:c25:d915:bca7
852c19:dd:d9:dd:c25:c25:d915:bca8/1272c19:dd:d9:dd:c25:c25:d915:bca9
862c19:dd:d9:dd:c25:c25:d915:bcaa/1272c19:dd:d9:dd:c25:c25:d915:bcab
872c19:dd:d9:dd:c25:c25:d915:bcac/1272c19:dd:d9:dd:c25:c25:d915:bcad
882c19:dd:d9:dd:c25:c25:d915:bcae/1272c19:dd:d9:dd:c25:c25:d915:bcaf
892c19:dd:d9:dd:c25:c25:d915:bcb0/1272c19:dd:d9:dd:c25:c25:d915:bcb1
902c19:dd:d9:dd:c25:c25:d915:bcb2/1272c19:dd:d9:dd:c25:c25:d915:bcb3
912c19:dd:d9:dd:c25:c25:d915:bcb4/1272c19:dd:d9:dd:c25:c25:d915:bcb5
922c19:dd:d9:dd:c25:c25:d915:bcb6/1272c19:dd:d9:dd:c25:c25:d915:bcb7
932c19:dd:d9:dd:c25:c25:d915:bcb8/1272c19:dd:d9:dd:c25:c25:d915:bcb9
942c19:dd:d9:dd:c25:c25:d915:bcba/1272c19:dd:d9:dd:c25:c25:d915:bcbb
952c19:dd:d9:dd:c25:c25:d915:bcbc/1272c19:dd:d9:dd:c25:c25:d915:bcbd
962c19:dd:d9:dd:c25:c25:d915:bcbe/1272c19:dd:d9:dd:c25:c25:d915:bcbf
972c19:dd:d9:dd:c25:c25:d915:bcc0/1272c19:dd:d9:dd:c25:c25:d915:bcc1
982c19:dd:d9:dd:c25:c25:d915:bcc2/1272c19:dd:d9:dd:c25:c25:d915:bcc3
992c19:dd:d9:dd:c25:c25:d915:bcc4/1272c19:dd:d9:dd:c25:c25:d915:bcc5
1002c19:dd:d9:dd:c25:c25:d915:bcc6/1272c19:dd:d9:dd:c25:c25:d915:bcc7
1012c19:dd:d9:dd:c25:c25:d915:bcc8/1272c19:dd:d9:dd:c25:c25:d915:bcc9
1022c19:dd:d9:dd:c25:c25:d915:bcca/1272c19:dd:d9:dd:c25:c25:d915:bccb
1032c19:dd:d9:dd:c25:c25:d915:bccc/1272c19:dd:d9:dd:c25:c25:d915:bccd
1042c19:dd:d9:dd:c25:c25:d915:bcce/1272c19:dd:d9:dd:c25:c25:d915:bccf
1052c19:dd:d9:dd:c25:c25:d915:bcd0/1272c19:dd:d9:dd:c25:c25:d915:bcd1
1062c19:dd:d9:dd:c25:c25:d915:bcd2/1272c19:dd:d9:dd:c25:c25:d915:bcd3
1072c19:dd:d9:dd:c25:c25:d915:bcd4/1272c19:dd:d9:dd:c25:c25:d915:bcd5
1082c19:dd:d9:dd:c25:c25:d915:bcd6/1272c19:dd:d9:dd:c25:c25:d915:bcd7
1092c19:dd:d9:dd:c25:c25:d915:bcd8/1272c19:dd:d9:dd:c25:c25:d915:bcd9
1102c19:dd:d9:dd:c25:c25:d915:bcda/1272c19:dd:d9:dd:c25:c25:d915:bcdb
1112c19:dd:d9:dd:c25:c25:d915:bcdc/1272c19:dd:d9:dd:c25:c25:d915:bcdd
1122c19:dd:d9:dd:c25:c25:d915:bcde/1272c19:dd:d9:dd:c25:c25:d915:bcdf
1132c19:dd:d9:dd:c25:c25:d915:bce0/1272c19:dd:d9:dd:c25:c25:d915:bce1
1142c19:dd:d9:dd:c25:c25:d915:bce2/1272c19:dd:d9:dd:c25:c25:d915:bce3
1152c19:dd:d9:dd:c25:c25:d915:bce4/1272c19:dd:d9:dd:c25:c25:d915:bce5
1162c19:dd:d9:dd:c25:c25:d915:bce6/1272c19:dd:d9:dd:c25:c25:d915:bce7
1172c19:dd:d9:dd:c25:c25:d915:bce8/1272c19:dd:d9:dd:c25:c25:d915:bce9
1182c19:dd:d9:dd:c25:c25:d915:bcea/1272c19:dd:d9:dd:c25:c25:d915:bceb
1192c19:dd:d9:dd:c25:c25:d915:bcec/1272c19:dd:d9:dd:c25:c25:d915:bced
1202c19:dd:d9:dd:c25:c25:d915:bcee/1272c19:dd:d9:dd:c25:c25:d915:bcef
1212c19:dd:d9:dd:c25:c25:d915:bcf0/1272c19:dd:d9:dd:c25:c25:d915:bcf1
1222c19:dd:d9:dd:c25:c25:d915:bcf2/1272c19:dd:d9:dd:c25:c25:d915:bcf3
1232c19:dd:d9:dd:c25:c25:d915:bcf4/1272c19:dd:d9:dd:c25:c25:d915:bcf5
1242c19:dd:d9:dd:c25:c25:d915:bcf6/1272c19:dd:d9:dd:c25:c25:d915:bcf7
1252c19:dd:d9:dd:c25:c25:d915:bcf8/1272c19:dd:d9:dd:c25:c25:d915:bcf9
1262c19:dd:d9:dd:c25:c25:d915:bcfa/1272c19:dd:d9:dd:c25:c25:d915:bcfb
1272c19:dd:d9:dd:c25:c25:d915:bcfc/1272c19:dd:d9:dd:c25:c25:d915:bcfd
1282c19:dd:d9:dd:c25:c25:d915:bcfe/1272c19:dd:d9:dd:c25:c25:d915:bcff
1292c19:dd:d9:dd:c25:c25:d915:bd00/1272c19:dd:d9:dd:c25:c25:d915:bd01
1302c19:dd:d9:dd:c25:c25:d915:bd02/1272c19:dd:d9:dd:c25:c25:d915:bd03
1312c19:dd:d9:dd:c25:c25:d915:bd04/1272c19:dd:d9:dd:c25:c25:d915:bd05
1322c19:dd:d9:dd:c25:c25:d915:bd06/1272c19:dd:d9:dd:c25:c25:d915:bd07
1332c19:dd:d9:dd:c25:c25:d915:bd08/1272c19:dd:d9:dd:c25:c25:d915:bd09
1342c19:dd:d9:dd:c25:c25:d915:bd0a/1272c19:dd:d9:dd:c25:c25:d915:bd0b
1352c19:dd:d9:dd:c25:c25:d915:bd0c/1272c19:dd:d9:dd:c25:c25:d915:bd0d
1362c19:dd:d9:dd:c25:c25:d915:bd0e/1272c19:dd:d9:dd:c25:c25:d915:bd0f
1372c19:dd:d9:dd:c25:c25:d915:bd10/1272c19:dd:d9:dd:c25:c25:d915:bd11
1382c19:dd:d9:dd:c25:c25:d915:bd12/1272c19:dd:d9:dd:c25:c25:d915:bd13
1392c19:dd:d9:dd:c25:c25:d915:bd14/1272c19:dd:d9:dd:c25:c25:d915:bd15
1402c19:dd:d9:dd:c25:c25:d915:bd16/1272c19:dd:d9:dd:c25:c25:d915:bd17
1412c19:dd:d9:dd:c25:c25:d915:bd18/1272c19:dd:d9:dd:c25:c25:d915:bd19
1422c19:dd:d9:dd:c25:c25:d915:bd1a/1272c19:dd:d9:dd:c25:c25:d915:bd1b
1432c19:dd:d9:dd:c25:c25:d915:bd1c/1272c19:dd:d9:dd:c25:c25:d915:bd1d
1442c19:dd:d9:dd:c25:c25:d915:bd1e/1272c19:dd:d9:dd:c25:c25:d915:bd1f
1452c19:dd:d9:dd:c25:c25:d915:bd20/1272c19:dd:d9:dd:c25:c25:d915:bd21
1462c19:dd:d9:dd:c25:c25:d915:bd22/1272c19:dd:d9:dd:c25:c25:d915:bd23
1472c19:dd:d9:dd:c25:c25:d915:bd24/1272c19:dd:d9:dd:c25:c25:d915:bd25
1482c19:dd:d9:dd:c25:c25:d915:bd26/1272c19:dd:d9:dd:c25:c25:d915:bd27
1492c19:dd:d9:dd:c25:c25:d915:bd28/1272c19:dd:d9:dd:c25:c25:d915:bd29
1502c19:dd:d9:dd:c25:c25:d915:bd2a/1272c19:dd:d9:dd:c25:c25:d915:bd2b
1512c19:dd:d9:dd:c25:c25:d915:bd2c/1272c19:dd:d9:dd:c25:c25:d915:bd2d
1522c19:dd:d9:dd:c25:c25:d915:bd2e/1272c19:dd:d9:dd:c25:c25:d915:bd2f
1532c19:dd:d9:dd:c25:c25:d915:bd30/1272c19:dd:d9:dd:c25:c25:d915:bd31
1542c19:dd:d9:dd:c25:c25:d915:bd32/1272c19:dd:d9:dd:c25:c25:d915:bd33
1552c19:dd:d9:dd:c25:c25:d915:bd34/1272c19:dd:d9:dd:c25:c25:d915:bd35
1562c19:dd:d9:dd:c25:c25:d915:bd36/1272c19:dd:d9:dd:c25:c25:d915:bd37
1572c19:dd:d9:dd:c25:c25:d915:bd38/1272c19:dd:d9:dd:c25:c25:d915:bd39
1582c19:dd:d9:dd:c25:c25:d915:bd3a/1272c19:dd:d9:dd:c25:c25:d915:bd3b
1592c19:dd:d9:dd:c25:c25:d915:bd3c/1272c19:dd:d9:dd:c25:c25:d915:bd3d
1602c19:dd:d9:dd:c25:c25:d915:bd3e/1272c19:dd:d9:dd:c25:c25:d915:bd3f
1612c19:dd:d9:dd:c25:c25:d915:bd40/1272c19:dd:d9:dd:c25:c25:d915:bd41
1622c19:dd:d9:dd:c25:c25:d915:bd42/1272c19:dd:d9:dd:c25:c25:d915:bd43
1632c19:dd:d9:dd:c25:c25:d915:bd44/1272c19:dd:d9:dd:c25:c25:d915:bd45
1642c19:dd:d9:dd:c25:c25:d915:bd46/1272c19:dd:d9:dd:c25:c25:d915:bd47
1652c19:dd:d9:dd:c25:c25:d915:bd48/1272c19:dd:d9:dd:c25:c25:d915:bd49
1662c19:dd:d9:dd:c25:c25:d915:bd4a/1272c19:dd:d9:dd:c25:c25:d915:bd4b
1672c19:dd:d9:dd:c25:c25:d915:bd4c/1272c19:dd:d9:dd:c25:c25:d915:bd4d
1682c19:dd:d9:dd:c25:c25:d915:bd4e/1272c19:dd:d9:dd:c25:c25:d915:bd4f
1692c19:dd:d9:dd:c25:c25:d915:bd50/1272c19:dd:d9:dd:c25:c25:d915:bd51
1702c19:dd:d9:dd:c25:c25:d915:bd52/1272c19:dd:d9:dd:c25:c25:d915:bd53
1712c19:dd:d9:dd:c25:c25:d915:bd54/1272c19:dd:d9:dd:c25:c25:d915:bd55
1722c19:dd:d9:dd:c25:c25:d915:bd56/1272c19:dd:d9:dd:c25:c25:d915:bd57
1732c19:dd:d9:dd:c25:c25:d915:bd58/1272c19:dd:d9:dd:c25:c25:d915:bd59
1742c19:dd:d9:dd:c25:c25:d915:bd5a/1272c19:dd:d9:dd:c25:c25:d915:bd5b
1752c19:dd:d9:dd:c25:c25:d915:bd5c/1272c19:dd:d9:dd:c25:c25:d915:bd5d
1762c19:dd:d9:dd:c25:c25:d915:bd5e/1272c19:dd:d9:dd:c25:c25:d915:bd5f
1772c19:dd:d9:dd:c25:c25:d915:bd60/1272c19:dd:d9:dd:c25:c25:d915:bd61
1782c19:dd:d9:dd:c25:c25:d915:bd62/1272c19:dd:d9:dd:c25:c25:d915:bd63
1792c19:dd:d9:dd:c25:c25:d915:bd64/1272c19:dd:d9:dd:c25:c25:d915:bd65
1802c19:dd:d9:dd:c25:c25:d915:bd66/1272c19:dd:d9:dd:c25:c25:d915:bd67
1812c19:dd:d9:dd:c25:c25:d915:bd68/1272c19:dd:d9:dd:c25:c25:d915:bd69
1822c19:dd:d9:dd:c25:c25:d915:bd6a/1272c19:dd:d9:dd:c25:c25:d915:bd6b
1832c19:dd:d9:dd:c25:c25:d915:bd6c/1272c19:dd:d9:dd:c25:c25:d915:bd6d
1842c19:dd:d9:dd:c25:c25:d915:bd6e/1272c19:dd:d9:dd:c25:c25:d915:bd6f
1852c19:dd:d9:dd:c25:c25:d915:bd70/1272c19:dd:d9:dd:c25:c25:d915:bd71
1862c19:dd:d9:dd:c25:c25:d915:bd72/1272c19:dd:d9:dd:c25:c25:d915:bd73
1872c19:dd:d9:dd:c25:c25:d915:bd74/1272c19:dd:d9:dd:c25:c25:d915:bd75
1882c19:dd:d9:dd:c25:c25:d915:bd76/1272c19:dd:d9:dd:c25:c25:d915:bd77
1892c19:dd:d9:dd:c25:c25:d915:bd78/1272c19:dd:d9:dd:c25:c25:d915:bd79
1902c19:dd:d9:dd:c25:c25:d915:bd7a/1272c19:dd:d9:dd:c25:c25:d915:bd7b
1912c19:dd:d9:dd:c25:c25:d915:bd7c/1272c19:dd:d9:dd:c25:c25:d915:bd7d
1922c19:dd:d9:dd:c25:c25:d915:bd7e/1272c19:dd:d9:dd:c25:c25:d915:bd7f
1932c19:dd:d9:dd:c25:c25:d915:bd80/1272c19:dd:d9:dd:c25:c25:d915:bd81
1942c19:dd:d9:dd:c25:c25:d915:bd82/1272c19:dd:d9:dd:c25:c25:d915:bd83
1952c19:dd:d9:dd:c25:c25:d915:bd84/1272c19:dd:d9:dd:c25:c25:d915:bd85
1962c19:dd:d9:dd:c25:c25:d915:bd86/1272c19:dd:d9:dd:c25:c25:d915:bd87
1972c19:dd:d9:dd:c25:c25:d915:bd88/1272c19:dd:d9:dd:c25:c25:d915:bd89
1982c19:dd:d9:dd:c25:c25:d915:bd8a/1272c19:dd:d9:dd:c25:c25:d915:bd8b
1992c19:dd:d9:dd:c25:c25:d915:bd8c/1272c19:dd:d9:dd:c25:c25:d915:bd8d
2002c19:dd:d9:dd:c25:c25:d915:bd8e/1272c19:dd:d9:dd:c25:c25:d915:bd8f
2012c19:dd:d9:dd:c25:c25:d915:bd90/1272c19:dd:d9:dd:c25:c25:d915:bd91
2022c19:dd:d9:dd:c25:c25:d915:bd92/1272c19:dd:d9:dd:c25:c25:d915:bd93
2032c19:dd:d9:dd:c25:c25:d915:bd94/1272c19:dd:d9:dd:c25:c25:d915:bd95
2042c19:dd:d9:dd:c25:c25:d915:bd96/1272c19:dd:d9:dd:c25:c25:d915:bd97
2052c19:dd:d9:dd:c25:c25:d915:bd98/1272c19:dd:d9:dd:c25:c25:d915:bd99
2062c19:dd:d9:dd:c25:c25:d915:bd9a/1272c19:dd:d9:dd:c25:c25:d915:bd9b
2072c19:dd:d9:dd:c25:c25:d915:bd9c/1272c19:dd:d9:dd:c25:c25:d915:bd9d
2082c19:dd:d9:dd:c25:c25:d915:bd9e/1272c19:dd:d9:dd:c25:c25:d915:bd9f
2092c19:dd:d9:dd:c25:c25:d915:bda0/1272c19:dd:d9:dd:c25:c25:d915:bda1
2102c19:dd:d9:dd:c25:c25:d915:bda2/1272c19:dd:d9:dd:c25:c25:d915:bda3
2112c19:dd:d9:dd:c25:c25:d915:bda4/1272c19:dd:d9:dd:c25:c25:d915:bda5
2122c19:dd:d9:dd:c25:c25:d915:bda6/1272c19:dd:d9:dd:c25:c25:d915:bda7
2132c19:dd:d9:dd:c25:c25:d915:bda8/1272c19:dd:d9:dd:c25:c25:d915:bda9
2142c19:dd:d9:dd:c25:c25:d915:bdaa/1272c19:dd:d9:dd:c25:c25:d915:bdab
2152c19:dd:d9:dd:c25:c25:d915:bdac/1272c19:dd:d9:dd:c25:c25:d915:bdad
2162c19:dd:d9:dd:c25:c25:d915:bdae/1272c19:dd:d9:dd:c25:c25:d915:bdaf
2172c19:dd:d9:dd:c25:c25:d915:bdb0/1272c19:dd:d9:dd:c25:c25:d915:bdb1
2182c19:dd:d9:dd:c25:c25:d915:bdb2/1272c19:dd:d9:dd:c25:c25:d915:bdb3
2192c19:dd:d9:dd:c25:c25:d915:bdb4/1272c19:dd:d9:dd:c25:c25:d915:bdb5
2202c19:dd:d9:dd:c25:c25:d915:bdb6/1272c19:dd:d9:dd:c25:c25:d915:bdb7
2212c19:dd:d9:dd:c25:c25:d915:bdb8/1272c19:dd:d9:dd:c25:c25:d915:bdb9
2222c19:dd:d9:dd:c25:c25:d915:bdba/1272c19:dd:d9:dd:c25:c25:d915:bdbb
2232c19:dd:d9:dd:c25:c25:d915:bdbc/1272c19:dd:d9:dd:c25:c25:d915:bdbd
2242c19:dd:d9:dd:c25:c25:d915:bdbe/1272c19:dd:d9:dd:c25:c25:d915:bdbf
2252c19:dd:d9:dd:c25:c25:d915:bdc0/1272c19:dd:d9:dd:c25:c25:d915:bdc1
2262c19:dd:d9:dd:c25:c25:d915:bdc2/1272c19:dd:d9:dd:c25:c25:d915:bdc3
2272c19:dd:d9:dd:c25:c25:d915:bdc4/1272c19:dd:d9:dd:c25:c25:d915:bdc5
2282c19:dd:d9:dd:c25:c25:d915:bdc6/1272c19:dd:d9:dd:c25:c25:d915:bdc7
2292c19:dd:d9:dd:c25:c25:d915:bdc8/1272c19:dd:d9:dd:c25:c25:d915:bdc9
2302c19:dd:d9:dd:c25:c25:d915:bdca/1272c19:dd:d9:dd:c25:c25:d915:bdcb
2312c19:dd:d9:dd:c25:c25:d915:bdcc/1272c19:dd:d9:dd:c25:c25:d915:bdcd
2322c19:dd:d9:dd:c25:c25:d915:bdce/1272c19:dd:d9:dd:c25:c25:d915:bdcf
2332c19:dd:d9:dd:c25:c25:d915:bdd0/1272c19:dd:d9:dd:c25:c25:d915:bdd1
2342c19:dd:d9:dd:c25:c25:d915:bdd2/1272c19:dd:d9:dd:c25:c25:d915:bdd3
2352c19:dd:d9:dd:c25:c25:d915:bdd4/1272c19:dd:d9:dd:c25:c25:d915:bdd5
2362c19:dd:d9:dd:c25:c25:d915:bdd6/1272c19:dd:d9:dd:c25:c25:d915:bdd7
2372c19:dd:d9:dd:c25:c25:d915:bdd8/1272c19:dd:d9:dd:c25:c25:d915:bdd9
2382c19:dd:d9:dd:c25:c25:d915:bdda/1272c19:dd:d9:dd:c25:c25:d915:bddb
2392c19:dd:d9:dd:c25:c25:d915:bddc/1272c19:dd:d9:dd:c25:c25:d915:bddd
2402c19:dd:d9:dd:c25:c25:d915:bdde/1272c19:dd:d9:dd:c25:c25:d915:bddf
2412c19:dd:d9:dd:c25:c25:d915:bde0/1272c19:dd:d9:dd:c25:c25:d915:bde1
2422c19:dd:d9:dd:c25:c25:d915:bde2/1272c19:dd:d9:dd:c25:c25:d915:bde3
2432c19:dd:d9:dd:c25:c25:d915:bde4/1272c19:dd:d9:dd:c25:c25:d915:bde5
2442c19:dd:d9:dd:c25:c25:d915:bde6/1272c19:dd:d9:dd:c25:c25:d915:bde7
2452c19:dd:d9:dd:c25:c25:d915:bde8/1272c19:dd:d9:dd:c25:c25:d915:bde9
2462c19:dd:d9:dd:c25:c25:d915:bdea/1272c19:dd:d9:dd:c25:c25:d915:bdeb
2472c19:dd:d9:dd:c25:c25:d915:bdec/1272c19:dd:d9:dd:c25:c25:d915:bded
2482c19:dd:d9:dd:c25:c25:d915:bdee/1272c19:dd:d9:dd:c25:c25:d915:bdef
2492c19:dd:d9:dd:c25:c25:d915:bdf0/1272c19:dd:d9:dd:c25:c25:d915:bdf1
2502c19:dd:d9:dd:c25:c25:d915:bdf2/1272c19:dd:d9:dd:c25:c25:d915:bdf3
2512c19:dd:d9:dd:c25:c25:d915:bdf4/1272c19:dd:d9:dd:c25:c25:d915:bdf5
2522c19:dd:d9:dd:c25:c25:d915:bdf6/1272c19:dd:d9:dd:c25:c25:d915:bdf7
2532c19:dd:d9:dd:c25:c25:d915:bdf8/1272c19:dd:d9:dd:c25:c25:d915:bdf9
2542c19:dd:d9:dd:c25:c25:d915:bdfa/1272c19:dd:d9:dd:c25:c25:d915:bdfb
2552c19:dd:d9:dd:c25:c25:d915:bdfc/1272c19:dd:d9:dd:c25:c25:d915:bdfd
2562c19:dd:d9:dd:c25:c25:d915:bdfe/1272c19:dd:d9:dd:c25:c25:d915:bdff

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.