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/114
Addresses16,384
/64 networksPart of one
Network
2c19:dd:d9:dd:c25:c25:61ba:c000/114
First address
2c19:dd:d9:dd:c25:c25:61ba:c000
Last address
2c19:dd:d9:dd:c25:c25:61ba:ffff
Addresses
16,384
/64 networks (LANs)
None: smaller than one /64 LAN
Full form
2c19:00dd:00d9:00dd:0c25:0c25:61ba:c000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zones
c.a.b.1.6.5.2.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.a.b.1.6.5.2.c.0.5.2.c.0.d.d.0.0.9.d.0.0.d.d.0.0.9.1.c.2.ip6.arpa
e.a.b.1.6.5.2.c.0.5.2.c.0.d.d.0.0.9.d.0.0.d.d.0.0.9.1.c.2.ip6.arpa
f.a.b.1.6.5.2.c.0.5.2.c.0.d.d.0.0.9.d.0.0.d.d.0.0.9.1.c.2.ip6.arpa
/114 is not on a 4-bit boundary, so it takes 4 /116 zones.
Split into smaller subnets/120

2c19:dd:d9:dd:c25:c25:61ba:c000/114 makes 64 subnets of /120.

Subnets
#SubnetLast address
12c19:dd:d9:dd:c25:c25:61ba:c000/1202c19:dd:d9:dd:c25:c25:61ba:c0ff
22c19:dd:d9:dd:c25:c25:61ba:c100/1202c19:dd:d9:dd:c25:c25:61ba:c1ff
32c19:dd:d9:dd:c25:c25:61ba:c200/1202c19:dd:d9:dd:c25:c25:61ba:c2ff
42c19:dd:d9:dd:c25:c25:61ba:c300/1202c19:dd:d9:dd:c25:c25:61ba:c3ff
52c19:dd:d9:dd:c25:c25:61ba:c400/1202c19:dd:d9:dd:c25:c25:61ba:c4ff
62c19:dd:d9:dd:c25:c25:61ba:c500/1202c19:dd:d9:dd:c25:c25:61ba:c5ff
72c19:dd:d9:dd:c25:c25:61ba:c600/1202c19:dd:d9:dd:c25:c25:61ba:c6ff
82c19:dd:d9:dd:c25:c25:61ba:c700/1202c19:dd:d9:dd:c25:c25:61ba:c7ff
92c19:dd:d9:dd:c25:c25:61ba:c800/1202c19:dd:d9:dd:c25:c25:61ba:c8ff
102c19:dd:d9:dd:c25:c25:61ba:c900/1202c19:dd:d9:dd:c25:c25:61ba:c9ff
112c19:dd:d9:dd:c25:c25:61ba:ca00/1202c19:dd:d9:dd:c25:c25:61ba:caff
122c19:dd:d9:dd:c25:c25:61ba:cb00/1202c19:dd:d9:dd:c25:c25:61ba:cbff
132c19:dd:d9:dd:c25:c25:61ba:cc00/1202c19:dd:d9:dd:c25:c25:61ba:ccff
142c19:dd:d9:dd:c25:c25:61ba:cd00/1202c19:dd:d9:dd:c25:c25:61ba:cdff
152c19:dd:d9:dd:c25:c25:61ba:ce00/1202c19:dd:d9:dd:c25:c25:61ba:ceff
162c19:dd:d9:dd:c25:c25:61ba:cf00/1202c19:dd:d9:dd:c25:c25:61ba:cfff
172c19:dd:d9:dd:c25:c25:61ba:d000/1202c19:dd:d9:dd:c25:c25:61ba:d0ff
182c19:dd:d9:dd:c25:c25:61ba:d100/1202c19:dd:d9:dd:c25:c25:61ba:d1ff
192c19:dd:d9:dd:c25:c25:61ba:d200/1202c19:dd:d9:dd:c25:c25:61ba:d2ff
202c19:dd:d9:dd:c25:c25:61ba:d300/1202c19:dd:d9:dd:c25:c25:61ba:d3ff
212c19:dd:d9:dd:c25:c25:61ba:d400/1202c19:dd:d9:dd:c25:c25:61ba:d4ff
222c19:dd:d9:dd:c25:c25:61ba:d500/1202c19:dd:d9:dd:c25:c25:61ba:d5ff
232c19:dd:d9:dd:c25:c25:61ba:d600/1202c19:dd:d9:dd:c25:c25:61ba:d6ff
242c19:dd:d9:dd:c25:c25:61ba:d700/1202c19:dd:d9:dd:c25:c25:61ba:d7ff
252c19:dd:d9:dd:c25:c25:61ba:d800/1202c19:dd:d9:dd:c25:c25:61ba:d8ff
262c19:dd:d9:dd:c25:c25:61ba:d900/1202c19:dd:d9:dd:c25:c25:61ba:d9ff
272c19:dd:d9:dd:c25:c25:61ba:da00/1202c19:dd:d9:dd:c25:c25:61ba:daff
282c19:dd:d9:dd:c25:c25:61ba:db00/1202c19:dd:d9:dd:c25:c25:61ba:dbff
292c19:dd:d9:dd:c25:c25:61ba:dc00/1202c19:dd:d9:dd:c25:c25:61ba:dcff
302c19:dd:d9:dd:c25:c25:61ba:dd00/1202c19:dd:d9:dd:c25:c25:61ba:ddff
312c19:dd:d9:dd:c25:c25:61ba:de00/1202c19:dd:d9:dd:c25:c25:61ba:deff
322c19:dd:d9:dd:c25:c25:61ba:df00/1202c19:dd:d9:dd:c25:c25:61ba:dfff
332c19:dd:d9:dd:c25:c25:61ba:e000/1202c19:dd:d9:dd:c25:c25:61ba:e0ff
342c19:dd:d9:dd:c25:c25:61ba:e100/1202c19:dd:d9:dd:c25:c25:61ba:e1ff
352c19:dd:d9:dd:c25:c25:61ba:e200/1202c19:dd:d9:dd:c25:c25:61ba:e2ff
362c19:dd:d9:dd:c25:c25:61ba:e300/1202c19:dd:d9:dd:c25:c25:61ba:e3ff
372c19:dd:d9:dd:c25:c25:61ba:e400/1202c19:dd:d9:dd:c25:c25:61ba:e4ff
382c19:dd:d9:dd:c25:c25:61ba:e500/1202c19:dd:d9:dd:c25:c25:61ba:e5ff
392c19:dd:d9:dd:c25:c25:61ba:e600/1202c19:dd:d9:dd:c25:c25:61ba:e6ff
402c19:dd:d9:dd:c25:c25:61ba:e700/1202c19:dd:d9:dd:c25:c25:61ba:e7ff
412c19:dd:d9:dd:c25:c25:61ba:e800/1202c19:dd:d9:dd:c25:c25:61ba:e8ff
422c19:dd:d9:dd:c25:c25:61ba:e900/1202c19:dd:d9:dd:c25:c25:61ba:e9ff
432c19:dd:d9:dd:c25:c25:61ba:ea00/1202c19:dd:d9:dd:c25:c25:61ba:eaff
442c19:dd:d9:dd:c25:c25:61ba:eb00/1202c19:dd:d9:dd:c25:c25:61ba:ebff
452c19:dd:d9:dd:c25:c25:61ba:ec00/1202c19:dd:d9:dd:c25:c25:61ba:ecff
462c19:dd:d9:dd:c25:c25:61ba:ed00/1202c19:dd:d9:dd:c25:c25:61ba:edff
472c19:dd:d9:dd:c25:c25:61ba:ee00/1202c19:dd:d9:dd:c25:c25:61ba:eeff
482c19:dd:d9:dd:c25:c25:61ba:ef00/1202c19:dd:d9:dd:c25:c25:61ba:efff
492c19:dd:d9:dd:c25:c25:61ba:f000/1202c19:dd:d9:dd:c25:c25:61ba:f0ff
502c19:dd:d9:dd:c25:c25:61ba:f100/1202c19:dd:d9:dd:c25:c25:61ba:f1ff
512c19:dd:d9:dd:c25:c25:61ba:f200/1202c19:dd:d9:dd:c25:c25:61ba:f2ff
522c19:dd:d9:dd:c25:c25:61ba:f300/1202c19:dd:d9:dd:c25:c25:61ba:f3ff
532c19:dd:d9:dd:c25:c25:61ba:f400/1202c19:dd:d9:dd:c25:c25:61ba:f4ff
542c19:dd:d9:dd:c25:c25:61ba:f500/1202c19:dd:d9:dd:c25:c25:61ba:f5ff
552c19:dd:d9:dd:c25:c25:61ba:f600/1202c19:dd:d9:dd:c25:c25:61ba:f6ff
562c19:dd:d9:dd:c25:c25:61ba:f700/1202c19:dd:d9:dd:c25:c25:61ba:f7ff
572c19:dd:d9:dd:c25:c25:61ba:f800/1202c19:dd:d9:dd:c25:c25:61ba:f8ff
582c19:dd:d9:dd:c25:c25:61ba:f900/1202c19:dd:d9:dd:c25:c25:61ba:f9ff
592c19:dd:d9:dd:c25:c25:61ba:fa00/1202c19:dd:d9:dd:c25:c25:61ba:faff
602c19:dd:d9:dd:c25:c25:61ba:fb00/1202c19:dd:d9:dd:c25:c25:61ba:fbff
612c19:dd:d9:dd:c25:c25:61ba:fc00/1202c19:dd:d9:dd:c25:c25:61ba:fcff
622c19:dd:d9:dd:c25:c25:61ba:fd00/1202c19:dd:d9:dd:c25:c25:61ba:fdff
632c19:dd:d9:dd:c25:c25:61ba:fe00/1202c19:dd:d9:dd:c25:c25:61ba:feff
642c19:dd:d9:dd:c25:c25:61ba:ff00/1202c19:dd:d9:dd:c25:c25:61ba: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