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:dd0:ec00:c25:c25:dde:2000/116
First address
2c19:dd:dd0:ec00:c25:c25:dde:2000
Last address
2c19:dd:dd0:ec00:c25:c25:dde:2fff
Addresses
4,096
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:0dd0:ec00:0c25:0c25:0dde:2000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
2.e.d.d.0.5.2.c.0.5.2.c.0.0.0.c.e.0.d.d.0.d.d.0.0.9.1.c.2.ip6.arpa
Split into smaller subnets/127
/117 (2)/118 (4)/119 (8)/120 (16)/124 (256)/127 (2,048)/128 (4,096)

2c19:dd:dd0:ec00:c25:c25:dde:2000/116 makes 2,048 subnets of /127; the first 256 are listed.

Subnets
#SubnetLast address
12c19:dd:dd0:ec00:c25:c25:dde:2000/1272c19:dd:dd0:ec00:c25:c25:dde:2001
22c19:dd:dd0:ec00:c25:c25:dde:2002/1272c19:dd:dd0:ec00:c25:c25:dde:2003
32c19:dd:dd0:ec00:c25:c25:dde:2004/1272c19:dd:dd0:ec00:c25:c25:dde:2005
42c19:dd:dd0:ec00:c25:c25:dde:2006/1272c19:dd:dd0:ec00:c25:c25:dde:2007
52c19:dd:dd0:ec00:c25:c25:dde:2008/1272c19:dd:dd0:ec00:c25:c25:dde:2009
62c19:dd:dd0:ec00:c25:c25:dde:200a/1272c19:dd:dd0:ec00:c25:c25:dde:200b
72c19:dd:dd0:ec00:c25:c25:dde:200c/1272c19:dd:dd0:ec00:c25:c25:dde:200d
82c19:dd:dd0:ec00:c25:c25:dde:200e/1272c19:dd:dd0:ec00:c25:c25:dde:200f
92c19:dd:dd0:ec00:c25:c25:dde:2010/1272c19:dd:dd0:ec00:c25:c25:dde:2011
102c19:dd:dd0:ec00:c25:c25:dde:2012/1272c19:dd:dd0:ec00:c25:c25:dde:2013
112c19:dd:dd0:ec00:c25:c25:dde:2014/1272c19:dd:dd0:ec00:c25:c25:dde:2015
122c19:dd:dd0:ec00:c25:c25:dde:2016/1272c19:dd:dd0:ec00:c25:c25:dde:2017
132c19:dd:dd0:ec00:c25:c25:dde:2018/1272c19:dd:dd0:ec00:c25:c25:dde:2019
142c19:dd:dd0:ec00:c25:c25:dde:201a/1272c19:dd:dd0:ec00:c25:c25:dde:201b
152c19:dd:dd0:ec00:c25:c25:dde:201c/1272c19:dd:dd0:ec00:c25:c25:dde:201d
162c19:dd:dd0:ec00:c25:c25:dde:201e/1272c19:dd:dd0:ec00:c25:c25:dde:201f
172c19:dd:dd0:ec00:c25:c25:dde:2020/1272c19:dd:dd0:ec00:c25:c25:dde:2021
182c19:dd:dd0:ec00:c25:c25:dde:2022/1272c19:dd:dd0:ec00:c25:c25:dde:2023
192c19:dd:dd0:ec00:c25:c25:dde:2024/1272c19:dd:dd0:ec00:c25:c25:dde:2025
202c19:dd:dd0:ec00:c25:c25:dde:2026/1272c19:dd:dd0:ec00:c25:c25:dde:2027
212c19:dd:dd0:ec00:c25:c25:dde:2028/1272c19:dd:dd0:ec00:c25:c25:dde:2029
222c19:dd:dd0:ec00:c25:c25:dde:202a/1272c19:dd:dd0:ec00:c25:c25:dde:202b
232c19:dd:dd0:ec00:c25:c25:dde:202c/1272c19:dd:dd0:ec00:c25:c25:dde:202d
242c19:dd:dd0:ec00:c25:c25:dde:202e/1272c19:dd:dd0:ec00:c25:c25:dde:202f
252c19:dd:dd0:ec00:c25:c25:dde:2030/1272c19:dd:dd0:ec00:c25:c25:dde:2031
262c19:dd:dd0:ec00:c25:c25:dde:2032/1272c19:dd:dd0:ec00:c25:c25:dde:2033
272c19:dd:dd0:ec00:c25:c25:dde:2034/1272c19:dd:dd0:ec00:c25:c25:dde:2035
282c19:dd:dd0:ec00:c25:c25:dde:2036/1272c19:dd:dd0:ec00:c25:c25:dde:2037
292c19:dd:dd0:ec00:c25:c25:dde:2038/1272c19:dd:dd0:ec00:c25:c25:dde:2039
302c19:dd:dd0:ec00:c25:c25:dde:203a/1272c19:dd:dd0:ec00:c25:c25:dde:203b
312c19:dd:dd0:ec00:c25:c25:dde:203c/1272c19:dd:dd0:ec00:c25:c25:dde:203d
322c19:dd:dd0:ec00:c25:c25:dde:203e/1272c19:dd:dd0:ec00:c25:c25:dde:203f
332c19:dd:dd0:ec00:c25:c25:dde:2040/1272c19:dd:dd0:ec00:c25:c25:dde:2041
342c19:dd:dd0:ec00:c25:c25:dde:2042/1272c19:dd:dd0:ec00:c25:c25:dde:2043
352c19:dd:dd0:ec00:c25:c25:dde:2044/1272c19:dd:dd0:ec00:c25:c25:dde:2045
362c19:dd:dd0:ec00:c25:c25:dde:2046/1272c19:dd:dd0:ec00:c25:c25:dde:2047
372c19:dd:dd0:ec00:c25:c25:dde:2048/1272c19:dd:dd0:ec00:c25:c25:dde:2049
382c19:dd:dd0:ec00:c25:c25:dde:204a/1272c19:dd:dd0:ec00:c25:c25:dde:204b
392c19:dd:dd0:ec00:c25:c25:dde:204c/1272c19:dd:dd0:ec00:c25:c25:dde:204d
402c19:dd:dd0:ec00:c25:c25:dde:204e/1272c19:dd:dd0:ec00:c25:c25:dde:204f
412c19:dd:dd0:ec00:c25:c25:dde:2050/1272c19:dd:dd0:ec00:c25:c25:dde:2051
422c19:dd:dd0:ec00:c25:c25:dde:2052/1272c19:dd:dd0:ec00:c25:c25:dde:2053
432c19:dd:dd0:ec00:c25:c25:dde:2054/1272c19:dd:dd0:ec00:c25:c25:dde:2055
442c19:dd:dd0:ec00:c25:c25:dde:2056/1272c19:dd:dd0:ec00:c25:c25:dde:2057
452c19:dd:dd0:ec00:c25:c25:dde:2058/1272c19:dd:dd0:ec00:c25:c25:dde:2059
462c19:dd:dd0:ec00:c25:c25:dde:205a/1272c19:dd:dd0:ec00:c25:c25:dde:205b
472c19:dd:dd0:ec00:c25:c25:dde:205c/1272c19:dd:dd0:ec00:c25:c25:dde:205d
482c19:dd:dd0:ec00:c25:c25:dde:205e/1272c19:dd:dd0:ec00:c25:c25:dde:205f
492c19:dd:dd0:ec00:c25:c25:dde:2060/1272c19:dd:dd0:ec00:c25:c25:dde:2061
502c19:dd:dd0:ec00:c25:c25:dde:2062/1272c19:dd:dd0:ec00:c25:c25:dde:2063
512c19:dd:dd0:ec00:c25:c25:dde:2064/1272c19:dd:dd0:ec00:c25:c25:dde:2065
522c19:dd:dd0:ec00:c25:c25:dde:2066/1272c19:dd:dd0:ec00:c25:c25:dde:2067
532c19:dd:dd0:ec00:c25:c25:dde:2068/1272c19:dd:dd0:ec00:c25:c25:dde:2069
542c19:dd:dd0:ec00:c25:c25:dde:206a/1272c19:dd:dd0:ec00:c25:c25:dde:206b
552c19:dd:dd0:ec00:c25:c25:dde:206c/1272c19:dd:dd0:ec00:c25:c25:dde:206d
562c19:dd:dd0:ec00:c25:c25:dde:206e/1272c19:dd:dd0:ec00:c25:c25:dde:206f
572c19:dd:dd0:ec00:c25:c25:dde:2070/1272c19:dd:dd0:ec00:c25:c25:dde:2071
582c19:dd:dd0:ec00:c25:c25:dde:2072/1272c19:dd:dd0:ec00:c25:c25:dde:2073
592c19:dd:dd0:ec00:c25:c25:dde:2074/1272c19:dd:dd0:ec00:c25:c25:dde:2075
602c19:dd:dd0:ec00:c25:c25:dde:2076/1272c19:dd:dd0:ec00:c25:c25:dde:2077
612c19:dd:dd0:ec00:c25:c25:dde:2078/1272c19:dd:dd0:ec00:c25:c25:dde:2079
622c19:dd:dd0:ec00:c25:c25:dde:207a/1272c19:dd:dd0:ec00:c25:c25:dde:207b
632c19:dd:dd0:ec00:c25:c25:dde:207c/1272c19:dd:dd0:ec00:c25:c25:dde:207d
642c19:dd:dd0:ec00:c25:c25:dde:207e/1272c19:dd:dd0:ec00:c25:c25:dde:207f
652c19:dd:dd0:ec00:c25:c25:dde:2080/1272c19:dd:dd0:ec00:c25:c25:dde:2081
662c19:dd:dd0:ec00:c25:c25:dde:2082/1272c19:dd:dd0:ec00:c25:c25:dde:2083
672c19:dd:dd0:ec00:c25:c25:dde:2084/1272c19:dd:dd0:ec00:c25:c25:dde:2085
682c19:dd:dd0:ec00:c25:c25:dde:2086/1272c19:dd:dd0:ec00:c25:c25:dde:2087
692c19:dd:dd0:ec00:c25:c25:dde:2088/1272c19:dd:dd0:ec00:c25:c25:dde:2089
702c19:dd:dd0:ec00:c25:c25:dde:208a/1272c19:dd:dd0:ec00:c25:c25:dde:208b
712c19:dd:dd0:ec00:c25:c25:dde:208c/1272c19:dd:dd0:ec00:c25:c25:dde:208d
722c19:dd:dd0:ec00:c25:c25:dde:208e/1272c19:dd:dd0:ec00:c25:c25:dde:208f
732c19:dd:dd0:ec00:c25:c25:dde:2090/1272c19:dd:dd0:ec00:c25:c25:dde:2091
742c19:dd:dd0:ec00:c25:c25:dde:2092/1272c19:dd:dd0:ec00:c25:c25:dde:2093
752c19:dd:dd0:ec00:c25:c25:dde:2094/1272c19:dd:dd0:ec00:c25:c25:dde:2095
762c19:dd:dd0:ec00:c25:c25:dde:2096/1272c19:dd:dd0:ec00:c25:c25:dde:2097
772c19:dd:dd0:ec00:c25:c25:dde:2098/1272c19:dd:dd0:ec00:c25:c25:dde:2099
782c19:dd:dd0:ec00:c25:c25:dde:209a/1272c19:dd:dd0:ec00:c25:c25:dde:209b
792c19:dd:dd0:ec00:c25:c25:dde:209c/1272c19:dd:dd0:ec00:c25:c25:dde:209d
802c19:dd:dd0:ec00:c25:c25:dde:209e/1272c19:dd:dd0:ec00:c25:c25:dde:209f
812c19:dd:dd0:ec00:c25:c25:dde:20a0/1272c19:dd:dd0:ec00:c25:c25:dde:20a1
822c19:dd:dd0:ec00:c25:c25:dde:20a2/1272c19:dd:dd0:ec00:c25:c25:dde:20a3
832c19:dd:dd0:ec00:c25:c25:dde:20a4/1272c19:dd:dd0:ec00:c25:c25:dde:20a5
842c19:dd:dd0:ec00:c25:c25:dde:20a6/1272c19:dd:dd0:ec00:c25:c25:dde:20a7
852c19:dd:dd0:ec00:c25:c25:dde:20a8/1272c19:dd:dd0:ec00:c25:c25:dde:20a9
862c19:dd:dd0:ec00:c25:c25:dde:20aa/1272c19:dd:dd0:ec00:c25:c25:dde:20ab
872c19:dd:dd0:ec00:c25:c25:dde:20ac/1272c19:dd:dd0:ec00:c25:c25:dde:20ad
882c19:dd:dd0:ec00:c25:c25:dde:20ae/1272c19:dd:dd0:ec00:c25:c25:dde:20af
892c19:dd:dd0:ec00:c25:c25:dde:20b0/1272c19:dd:dd0:ec00:c25:c25:dde:20b1
902c19:dd:dd0:ec00:c25:c25:dde:20b2/1272c19:dd:dd0:ec00:c25:c25:dde:20b3
912c19:dd:dd0:ec00:c25:c25:dde:20b4/1272c19:dd:dd0:ec00:c25:c25:dde:20b5
922c19:dd:dd0:ec00:c25:c25:dde:20b6/1272c19:dd:dd0:ec00:c25:c25:dde:20b7
932c19:dd:dd0:ec00:c25:c25:dde:20b8/1272c19:dd:dd0:ec00:c25:c25:dde:20b9
942c19:dd:dd0:ec00:c25:c25:dde:20ba/1272c19:dd:dd0:ec00:c25:c25:dde:20bb
952c19:dd:dd0:ec00:c25:c25:dde:20bc/1272c19:dd:dd0:ec00:c25:c25:dde:20bd
962c19:dd:dd0:ec00:c25:c25:dde:20be/1272c19:dd:dd0:ec00:c25:c25:dde:20bf
972c19:dd:dd0:ec00:c25:c25:dde:20c0/1272c19:dd:dd0:ec00:c25:c25:dde:20c1
982c19:dd:dd0:ec00:c25:c25:dde:20c2/1272c19:dd:dd0:ec00:c25:c25:dde:20c3
992c19:dd:dd0:ec00:c25:c25:dde:20c4/1272c19:dd:dd0:ec00:c25:c25:dde:20c5
1002c19:dd:dd0:ec00:c25:c25:dde:20c6/1272c19:dd:dd0:ec00:c25:c25:dde:20c7
1012c19:dd:dd0:ec00:c25:c25:dde:20c8/1272c19:dd:dd0:ec00:c25:c25:dde:20c9
1022c19:dd:dd0:ec00:c25:c25:dde:20ca/1272c19:dd:dd0:ec00:c25:c25:dde:20cb
1032c19:dd:dd0:ec00:c25:c25:dde:20cc/1272c19:dd:dd0:ec00:c25:c25:dde:20cd
1042c19:dd:dd0:ec00:c25:c25:dde:20ce/1272c19:dd:dd0:ec00:c25:c25:dde:20cf
1052c19:dd:dd0:ec00:c25:c25:dde:20d0/1272c19:dd:dd0:ec00:c25:c25:dde:20d1
1062c19:dd:dd0:ec00:c25:c25:dde:20d2/1272c19:dd:dd0:ec00:c25:c25:dde:20d3
1072c19:dd:dd0:ec00:c25:c25:dde:20d4/1272c19:dd:dd0:ec00:c25:c25:dde:20d5
1082c19:dd:dd0:ec00:c25:c25:dde:20d6/1272c19:dd:dd0:ec00:c25:c25:dde:20d7
1092c19:dd:dd0:ec00:c25:c25:dde:20d8/1272c19:dd:dd0:ec00:c25:c25:dde:20d9
1102c19:dd:dd0:ec00:c25:c25:dde:20da/1272c19:dd:dd0:ec00:c25:c25:dde:20db
1112c19:dd:dd0:ec00:c25:c25:dde:20dc/1272c19:dd:dd0:ec00:c25:c25:dde:20dd
1122c19:dd:dd0:ec00:c25:c25:dde:20de/1272c19:dd:dd0:ec00:c25:c25:dde:20df
1132c19:dd:dd0:ec00:c25:c25:dde:20e0/1272c19:dd:dd0:ec00:c25:c25:dde:20e1
1142c19:dd:dd0:ec00:c25:c25:dde:20e2/1272c19:dd:dd0:ec00:c25:c25:dde:20e3
1152c19:dd:dd0:ec00:c25:c25:dde:20e4/1272c19:dd:dd0:ec00:c25:c25:dde:20e5
1162c19:dd:dd0:ec00:c25:c25:dde:20e6/1272c19:dd:dd0:ec00:c25:c25:dde:20e7
1172c19:dd:dd0:ec00:c25:c25:dde:20e8/1272c19:dd:dd0:ec00:c25:c25:dde:20e9
1182c19:dd:dd0:ec00:c25:c25:dde:20ea/1272c19:dd:dd0:ec00:c25:c25:dde:20eb
1192c19:dd:dd0:ec00:c25:c25:dde:20ec/1272c19:dd:dd0:ec00:c25:c25:dde:20ed
1202c19:dd:dd0:ec00:c25:c25:dde:20ee/1272c19:dd:dd0:ec00:c25:c25:dde:20ef
1212c19:dd:dd0:ec00:c25:c25:dde:20f0/1272c19:dd:dd0:ec00:c25:c25:dde:20f1
1222c19:dd:dd0:ec00:c25:c25:dde:20f2/1272c19:dd:dd0:ec00:c25:c25:dde:20f3
1232c19:dd:dd0:ec00:c25:c25:dde:20f4/1272c19:dd:dd0:ec00:c25:c25:dde:20f5
1242c19:dd:dd0:ec00:c25:c25:dde:20f6/1272c19:dd:dd0:ec00:c25:c25:dde:20f7
1252c19:dd:dd0:ec00:c25:c25:dde:20f8/1272c19:dd:dd0:ec00:c25:c25:dde:20f9
1262c19:dd:dd0:ec00:c25:c25:dde:20fa/1272c19:dd:dd0:ec00:c25:c25:dde:20fb
1272c19:dd:dd0:ec00:c25:c25:dde:20fc/1272c19:dd:dd0:ec00:c25:c25:dde:20fd
1282c19:dd:dd0:ec00:c25:c25:dde:20fe/1272c19:dd:dd0:ec00:c25:c25:dde:20ff
1292c19:dd:dd0:ec00:c25:c25:dde:2100/1272c19:dd:dd0:ec00:c25:c25:dde:2101
1302c19:dd:dd0:ec00:c25:c25:dde:2102/1272c19:dd:dd0:ec00:c25:c25:dde:2103
1312c19:dd:dd0:ec00:c25:c25:dde:2104/1272c19:dd:dd0:ec00:c25:c25:dde:2105
1322c19:dd:dd0:ec00:c25:c25:dde:2106/1272c19:dd:dd0:ec00:c25:c25:dde:2107
1332c19:dd:dd0:ec00:c25:c25:dde:2108/1272c19:dd:dd0:ec00:c25:c25:dde:2109
1342c19:dd:dd0:ec00:c25:c25:dde:210a/1272c19:dd:dd0:ec00:c25:c25:dde:210b
1352c19:dd:dd0:ec00:c25:c25:dde:210c/1272c19:dd:dd0:ec00:c25:c25:dde:210d
1362c19:dd:dd0:ec00:c25:c25:dde:210e/1272c19:dd:dd0:ec00:c25:c25:dde:210f
1372c19:dd:dd0:ec00:c25:c25:dde:2110/1272c19:dd:dd0:ec00:c25:c25:dde:2111
1382c19:dd:dd0:ec00:c25:c25:dde:2112/1272c19:dd:dd0:ec00:c25:c25:dde:2113
1392c19:dd:dd0:ec00:c25:c25:dde:2114/1272c19:dd:dd0:ec00:c25:c25:dde:2115
1402c19:dd:dd0:ec00:c25:c25:dde:2116/1272c19:dd:dd0:ec00:c25:c25:dde:2117
1412c19:dd:dd0:ec00:c25:c25:dde:2118/1272c19:dd:dd0:ec00:c25:c25:dde:2119
1422c19:dd:dd0:ec00:c25:c25:dde:211a/1272c19:dd:dd0:ec00:c25:c25:dde:211b
1432c19:dd:dd0:ec00:c25:c25:dde:211c/1272c19:dd:dd0:ec00:c25:c25:dde:211d
1442c19:dd:dd0:ec00:c25:c25:dde:211e/1272c19:dd:dd0:ec00:c25:c25:dde:211f
1452c19:dd:dd0:ec00:c25:c25:dde:2120/1272c19:dd:dd0:ec00:c25:c25:dde:2121
1462c19:dd:dd0:ec00:c25:c25:dde:2122/1272c19:dd:dd0:ec00:c25:c25:dde:2123
1472c19:dd:dd0:ec00:c25:c25:dde:2124/1272c19:dd:dd0:ec00:c25:c25:dde:2125
1482c19:dd:dd0:ec00:c25:c25:dde:2126/1272c19:dd:dd0:ec00:c25:c25:dde:2127
1492c19:dd:dd0:ec00:c25:c25:dde:2128/1272c19:dd:dd0:ec00:c25:c25:dde:2129
1502c19:dd:dd0:ec00:c25:c25:dde:212a/1272c19:dd:dd0:ec00:c25:c25:dde:212b
1512c19:dd:dd0:ec00:c25:c25:dde:212c/1272c19:dd:dd0:ec00:c25:c25:dde:212d
1522c19:dd:dd0:ec00:c25:c25:dde:212e/1272c19:dd:dd0:ec00:c25:c25:dde:212f
1532c19:dd:dd0:ec00:c25:c25:dde:2130/1272c19:dd:dd0:ec00:c25:c25:dde:2131
1542c19:dd:dd0:ec00:c25:c25:dde:2132/1272c19:dd:dd0:ec00:c25:c25:dde:2133
1552c19:dd:dd0:ec00:c25:c25:dde:2134/1272c19:dd:dd0:ec00:c25:c25:dde:2135
1562c19:dd:dd0:ec00:c25:c25:dde:2136/1272c19:dd:dd0:ec00:c25:c25:dde:2137
1572c19:dd:dd0:ec00:c25:c25:dde:2138/1272c19:dd:dd0:ec00:c25:c25:dde:2139
1582c19:dd:dd0:ec00:c25:c25:dde:213a/1272c19:dd:dd0:ec00:c25:c25:dde:213b
1592c19:dd:dd0:ec00:c25:c25:dde:213c/1272c19:dd:dd0:ec00:c25:c25:dde:213d
1602c19:dd:dd0:ec00:c25:c25:dde:213e/1272c19:dd:dd0:ec00:c25:c25:dde:213f
1612c19:dd:dd0:ec00:c25:c25:dde:2140/1272c19:dd:dd0:ec00:c25:c25:dde:2141
1622c19:dd:dd0:ec00:c25:c25:dde:2142/1272c19:dd:dd0:ec00:c25:c25:dde:2143
1632c19:dd:dd0:ec00:c25:c25:dde:2144/1272c19:dd:dd0:ec00:c25:c25:dde:2145
1642c19:dd:dd0:ec00:c25:c25:dde:2146/1272c19:dd:dd0:ec00:c25:c25:dde:2147
1652c19:dd:dd0:ec00:c25:c25:dde:2148/1272c19:dd:dd0:ec00:c25:c25:dde:2149
1662c19:dd:dd0:ec00:c25:c25:dde:214a/1272c19:dd:dd0:ec00:c25:c25:dde:214b
1672c19:dd:dd0:ec00:c25:c25:dde:214c/1272c19:dd:dd0:ec00:c25:c25:dde:214d
1682c19:dd:dd0:ec00:c25:c25:dde:214e/1272c19:dd:dd0:ec00:c25:c25:dde:214f
1692c19:dd:dd0:ec00:c25:c25:dde:2150/1272c19:dd:dd0:ec00:c25:c25:dde:2151
1702c19:dd:dd0:ec00:c25:c25:dde:2152/1272c19:dd:dd0:ec00:c25:c25:dde:2153
1712c19:dd:dd0:ec00:c25:c25:dde:2154/1272c19:dd:dd0:ec00:c25:c25:dde:2155
1722c19:dd:dd0:ec00:c25:c25:dde:2156/1272c19:dd:dd0:ec00:c25:c25:dde:2157
1732c19:dd:dd0:ec00:c25:c25:dde:2158/1272c19:dd:dd0:ec00:c25:c25:dde:2159
1742c19:dd:dd0:ec00:c25:c25:dde:215a/1272c19:dd:dd0:ec00:c25:c25:dde:215b
1752c19:dd:dd0:ec00:c25:c25:dde:215c/1272c19:dd:dd0:ec00:c25:c25:dde:215d
1762c19:dd:dd0:ec00:c25:c25:dde:215e/1272c19:dd:dd0:ec00:c25:c25:dde:215f
1772c19:dd:dd0:ec00:c25:c25:dde:2160/1272c19:dd:dd0:ec00:c25:c25:dde:2161
1782c19:dd:dd0:ec00:c25:c25:dde:2162/1272c19:dd:dd0:ec00:c25:c25:dde:2163
1792c19:dd:dd0:ec00:c25:c25:dde:2164/1272c19:dd:dd0:ec00:c25:c25:dde:2165
1802c19:dd:dd0:ec00:c25:c25:dde:2166/1272c19:dd:dd0:ec00:c25:c25:dde:2167
1812c19:dd:dd0:ec00:c25:c25:dde:2168/1272c19:dd:dd0:ec00:c25:c25:dde:2169
1822c19:dd:dd0:ec00:c25:c25:dde:216a/1272c19:dd:dd0:ec00:c25:c25:dde:216b
1832c19:dd:dd0:ec00:c25:c25:dde:216c/1272c19:dd:dd0:ec00:c25:c25:dde:216d
1842c19:dd:dd0:ec00:c25:c25:dde:216e/1272c19:dd:dd0:ec00:c25:c25:dde:216f
1852c19:dd:dd0:ec00:c25:c25:dde:2170/1272c19:dd:dd0:ec00:c25:c25:dde:2171
1862c19:dd:dd0:ec00:c25:c25:dde:2172/1272c19:dd:dd0:ec00:c25:c25:dde:2173
1872c19:dd:dd0:ec00:c25:c25:dde:2174/1272c19:dd:dd0:ec00:c25:c25:dde:2175
1882c19:dd:dd0:ec00:c25:c25:dde:2176/1272c19:dd:dd0:ec00:c25:c25:dde:2177
1892c19:dd:dd0:ec00:c25:c25:dde:2178/1272c19:dd:dd0:ec00:c25:c25:dde:2179
1902c19:dd:dd0:ec00:c25:c25:dde:217a/1272c19:dd:dd0:ec00:c25:c25:dde:217b
1912c19:dd:dd0:ec00:c25:c25:dde:217c/1272c19:dd:dd0:ec00:c25:c25:dde:217d
1922c19:dd:dd0:ec00:c25:c25:dde:217e/1272c19:dd:dd0:ec00:c25:c25:dde:217f
1932c19:dd:dd0:ec00:c25:c25:dde:2180/1272c19:dd:dd0:ec00:c25:c25:dde:2181
1942c19:dd:dd0:ec00:c25:c25:dde:2182/1272c19:dd:dd0:ec00:c25:c25:dde:2183
1952c19:dd:dd0:ec00:c25:c25:dde:2184/1272c19:dd:dd0:ec00:c25:c25:dde:2185
1962c19:dd:dd0:ec00:c25:c25:dde:2186/1272c19:dd:dd0:ec00:c25:c25:dde:2187
1972c19:dd:dd0:ec00:c25:c25:dde:2188/1272c19:dd:dd0:ec00:c25:c25:dde:2189
1982c19:dd:dd0:ec00:c25:c25:dde:218a/1272c19:dd:dd0:ec00:c25:c25:dde:218b
1992c19:dd:dd0:ec00:c25:c25:dde:218c/1272c19:dd:dd0:ec00:c25:c25:dde:218d
2002c19:dd:dd0:ec00:c25:c25:dde:218e/1272c19:dd:dd0:ec00:c25:c25:dde:218f
2012c19:dd:dd0:ec00:c25:c25:dde:2190/1272c19:dd:dd0:ec00:c25:c25:dde:2191
2022c19:dd:dd0:ec00:c25:c25:dde:2192/1272c19:dd:dd0:ec00:c25:c25:dde:2193
2032c19:dd:dd0:ec00:c25:c25:dde:2194/1272c19:dd:dd0:ec00:c25:c25:dde:2195
2042c19:dd:dd0:ec00:c25:c25:dde:2196/1272c19:dd:dd0:ec00:c25:c25:dde:2197
2052c19:dd:dd0:ec00:c25:c25:dde:2198/1272c19:dd:dd0:ec00:c25:c25:dde:2199
2062c19:dd:dd0:ec00:c25:c25:dde:219a/1272c19:dd:dd0:ec00:c25:c25:dde:219b
2072c19:dd:dd0:ec00:c25:c25:dde:219c/1272c19:dd:dd0:ec00:c25:c25:dde:219d
2082c19:dd:dd0:ec00:c25:c25:dde:219e/1272c19:dd:dd0:ec00:c25:c25:dde:219f
2092c19:dd:dd0:ec00:c25:c25:dde:21a0/1272c19:dd:dd0:ec00:c25:c25:dde:21a1
2102c19:dd:dd0:ec00:c25:c25:dde:21a2/1272c19:dd:dd0:ec00:c25:c25:dde:21a3
2112c19:dd:dd0:ec00:c25:c25:dde:21a4/1272c19:dd:dd0:ec00:c25:c25:dde:21a5
2122c19:dd:dd0:ec00:c25:c25:dde:21a6/1272c19:dd:dd0:ec00:c25:c25:dde:21a7
2132c19:dd:dd0:ec00:c25:c25:dde:21a8/1272c19:dd:dd0:ec00:c25:c25:dde:21a9
2142c19:dd:dd0:ec00:c25:c25:dde:21aa/1272c19:dd:dd0:ec00:c25:c25:dde:21ab
2152c19:dd:dd0:ec00:c25:c25:dde:21ac/1272c19:dd:dd0:ec00:c25:c25:dde:21ad
2162c19:dd:dd0:ec00:c25:c25:dde:21ae/1272c19:dd:dd0:ec00:c25:c25:dde:21af
2172c19:dd:dd0:ec00:c25:c25:dde:21b0/1272c19:dd:dd0:ec00:c25:c25:dde:21b1
2182c19:dd:dd0:ec00:c25:c25:dde:21b2/1272c19:dd:dd0:ec00:c25:c25:dde:21b3
2192c19:dd:dd0:ec00:c25:c25:dde:21b4/1272c19:dd:dd0:ec00:c25:c25:dde:21b5
2202c19:dd:dd0:ec00:c25:c25:dde:21b6/1272c19:dd:dd0:ec00:c25:c25:dde:21b7
2212c19:dd:dd0:ec00:c25:c25:dde:21b8/1272c19:dd:dd0:ec00:c25:c25:dde:21b9
2222c19:dd:dd0:ec00:c25:c25:dde:21ba/1272c19:dd:dd0:ec00:c25:c25:dde:21bb
2232c19:dd:dd0:ec00:c25:c25:dde:21bc/1272c19:dd:dd0:ec00:c25:c25:dde:21bd
2242c19:dd:dd0:ec00:c25:c25:dde:21be/1272c19:dd:dd0:ec00:c25:c25:dde:21bf
2252c19:dd:dd0:ec00:c25:c25:dde:21c0/1272c19:dd:dd0:ec00:c25:c25:dde:21c1
2262c19:dd:dd0:ec00:c25:c25:dde:21c2/1272c19:dd:dd0:ec00:c25:c25:dde:21c3
2272c19:dd:dd0:ec00:c25:c25:dde:21c4/1272c19:dd:dd0:ec00:c25:c25:dde:21c5
2282c19:dd:dd0:ec00:c25:c25:dde:21c6/1272c19:dd:dd0:ec00:c25:c25:dde:21c7
2292c19:dd:dd0:ec00:c25:c25:dde:21c8/1272c19:dd:dd0:ec00:c25:c25:dde:21c9
2302c19:dd:dd0:ec00:c25:c25:dde:21ca/1272c19:dd:dd0:ec00:c25:c25:dde:21cb
2312c19:dd:dd0:ec00:c25:c25:dde:21cc/1272c19:dd:dd0:ec00:c25:c25:dde:21cd
2322c19:dd:dd0:ec00:c25:c25:dde:21ce/1272c19:dd:dd0:ec00:c25:c25:dde:21cf
2332c19:dd:dd0:ec00:c25:c25:dde:21d0/1272c19:dd:dd0:ec00:c25:c25:dde:21d1
2342c19:dd:dd0:ec00:c25:c25:dde:21d2/1272c19:dd:dd0:ec00:c25:c25:dde:21d3
2352c19:dd:dd0:ec00:c25:c25:dde:21d4/1272c19:dd:dd0:ec00:c25:c25:dde:21d5
2362c19:dd:dd0:ec00:c25:c25:dde:21d6/1272c19:dd:dd0:ec00:c25:c25:dde:21d7
2372c19:dd:dd0:ec00:c25:c25:dde:21d8/1272c19:dd:dd0:ec00:c25:c25:dde:21d9
2382c19:dd:dd0:ec00:c25:c25:dde:21da/1272c19:dd:dd0:ec00:c25:c25:dde:21db
2392c19:dd:dd0:ec00:c25:c25:dde:21dc/1272c19:dd:dd0:ec00:c25:c25:dde:21dd
2402c19:dd:dd0:ec00:c25:c25:dde:21de/1272c19:dd:dd0:ec00:c25:c25:dde:21df
2412c19:dd:dd0:ec00:c25:c25:dde:21e0/1272c19:dd:dd0:ec00:c25:c25:dde:21e1
2422c19:dd:dd0:ec00:c25:c25:dde:21e2/1272c19:dd:dd0:ec00:c25:c25:dde:21e3
2432c19:dd:dd0:ec00:c25:c25:dde:21e4/1272c19:dd:dd0:ec00:c25:c25:dde:21e5
2442c19:dd:dd0:ec00:c25:c25:dde:21e6/1272c19:dd:dd0:ec00:c25:c25:dde:21e7
2452c19:dd:dd0:ec00:c25:c25:dde:21e8/1272c19:dd:dd0:ec00:c25:c25:dde:21e9
2462c19:dd:dd0:ec00:c25:c25:dde:21ea/1272c19:dd:dd0:ec00:c25:c25:dde:21eb
2472c19:dd:dd0:ec00:c25:c25:dde:21ec/1272c19:dd:dd0:ec00:c25:c25:dde:21ed
2482c19:dd:dd0:ec00:c25:c25:dde:21ee/1272c19:dd:dd0:ec00:c25:c25:dde:21ef
2492c19:dd:dd0:ec00:c25:c25:dde:21f0/1272c19:dd:dd0:ec00:c25:c25:dde:21f1
2502c19:dd:dd0:ec00:c25:c25:dde:21f2/1272c19:dd:dd0:ec00:c25:c25:dde:21f3
2512c19:dd:dd0:ec00:c25:c25:dde:21f4/1272c19:dd:dd0:ec00:c25:c25:dde:21f5
2522c19:dd:dd0:ec00:c25:c25:dde:21f6/1272c19:dd:dd0:ec00:c25:c25:dde:21f7
2532c19:dd:dd0:ec00:c25:c25:dde:21f8/1272c19:dd:dd0:ec00:c25:c25:dde:21f9
2542c19:dd:dd0:ec00:c25:c25:dde:21fa/1272c19:dd:dd0:ec00:c25:c25:dde:21fb
2552c19:dd:dd0:ec00:c25:c25:dde:21fc/1272c19:dd:dd0:ec00:c25:c25:dde:21fd
2562c19:dd:dd0:ec00:c25:c25:dde:21fe/1272c19:dd:dd0:ec00:c25:c25:dde:21ff

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.