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.

Network142.78.0.0/17
Usable hosts32,766
Subnet mask255.255.128.0
Addresses32,768
Network address
142.78.0.0
Broadcast address
142.78.127.255
First usable
142.78.0.1
Last usable
142.78.127.254
Usable hosts
32,766 (32,768 less the network and broadcast addresses)
Subnet mask
255.255.128.0
Wildcard mask
0.0.127.255 (Cisco ACLs, OSPF)
Prefix length
/17
Type
Public public
Old class
B (default /16)
As numbers
Hex 8E4E0000 · Integer 2387476480 to 2387509247
Reverse DNS zones
0.78.142.in-addr.arpa
1.78.142.in-addr.arpa
2.78.142.in-addr.arpa
3.78.142.in-addr.arpa
4.78.142.in-addr.arpa
5.78.142.in-addr.arpa
6.78.142.in-addr.arpa
7.78.142.in-addr.arpa
8.78.142.in-addr.arpa
9.78.142.in-addr.arpa
10.78.142.in-addr.arpa
11.78.142.in-addr.arpa
12.78.142.in-addr.arpa
13.78.142.in-addr.arpa
14.78.142.in-addr.arpa
15.78.142.in-addr.arpa
and 112 more
/17 is not on a 8-bit boundary, so it takes 128 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address10001110.01001110.00000000.00000000142.78.0.0
Subnet mask11111111.11111111.10000000.00000000255.255.128.0
Network10001110.01001110.00000000.00000000142.78.0.0
Broadcast10001110.01001110.01111111.11111111142.78.127.255
Split into smaller subnets/24

142.78.0.0/17 makes 128 subnets of /24.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1142.78.0.0/24142.78.0.1 to 142.78.0.254142.78.0.255254
2142.78.1.0/24142.78.1.1 to 142.78.1.254142.78.1.255254
3142.78.2.0/24142.78.2.1 to 142.78.2.254142.78.2.255254
4142.78.3.0/24142.78.3.1 to 142.78.3.254142.78.3.255254
5142.78.4.0/24142.78.4.1 to 142.78.4.254142.78.4.255254
6142.78.5.0/24142.78.5.1 to 142.78.5.254142.78.5.255254
7142.78.6.0/24142.78.6.1 to 142.78.6.254142.78.6.255254
8142.78.7.0/24142.78.7.1 to 142.78.7.254142.78.7.255254
9142.78.8.0/24142.78.8.1 to 142.78.8.254142.78.8.255254
10142.78.9.0/24142.78.9.1 to 142.78.9.254142.78.9.255254
11142.78.10.0/24142.78.10.1 to 142.78.10.254142.78.10.255254
12142.78.11.0/24142.78.11.1 to 142.78.11.254142.78.11.255254
13142.78.12.0/24142.78.12.1 to 142.78.12.254142.78.12.255254
14142.78.13.0/24142.78.13.1 to 142.78.13.254142.78.13.255254
15142.78.14.0/24142.78.14.1 to 142.78.14.254142.78.14.255254
16142.78.15.0/24142.78.15.1 to 142.78.15.254142.78.15.255254
17142.78.16.0/24142.78.16.1 to 142.78.16.254142.78.16.255254
18142.78.17.0/24142.78.17.1 to 142.78.17.254142.78.17.255254
19142.78.18.0/24142.78.18.1 to 142.78.18.254142.78.18.255254
20142.78.19.0/24142.78.19.1 to 142.78.19.254142.78.19.255254
21142.78.20.0/24142.78.20.1 to 142.78.20.254142.78.20.255254
22142.78.21.0/24142.78.21.1 to 142.78.21.254142.78.21.255254
23142.78.22.0/24142.78.22.1 to 142.78.22.254142.78.22.255254
24142.78.23.0/24142.78.23.1 to 142.78.23.254142.78.23.255254
25142.78.24.0/24142.78.24.1 to 142.78.24.254142.78.24.255254
26142.78.25.0/24142.78.25.1 to 142.78.25.254142.78.25.255254
27142.78.26.0/24142.78.26.1 to 142.78.26.254142.78.26.255254
28142.78.27.0/24142.78.27.1 to 142.78.27.254142.78.27.255254
29142.78.28.0/24142.78.28.1 to 142.78.28.254142.78.28.255254
30142.78.29.0/24142.78.29.1 to 142.78.29.254142.78.29.255254
31142.78.30.0/24142.78.30.1 to 142.78.30.254142.78.30.255254
32142.78.31.0/24142.78.31.1 to 142.78.31.254142.78.31.255254
33142.78.32.0/24142.78.32.1 to 142.78.32.254142.78.32.255254
34142.78.33.0/24142.78.33.1 to 142.78.33.254142.78.33.255254
35142.78.34.0/24142.78.34.1 to 142.78.34.254142.78.34.255254
36142.78.35.0/24142.78.35.1 to 142.78.35.254142.78.35.255254
37142.78.36.0/24142.78.36.1 to 142.78.36.254142.78.36.255254
38142.78.37.0/24142.78.37.1 to 142.78.37.254142.78.37.255254
39142.78.38.0/24142.78.38.1 to 142.78.38.254142.78.38.255254
40142.78.39.0/24142.78.39.1 to 142.78.39.254142.78.39.255254
41142.78.40.0/24142.78.40.1 to 142.78.40.254142.78.40.255254
42142.78.41.0/24142.78.41.1 to 142.78.41.254142.78.41.255254
43142.78.42.0/24142.78.42.1 to 142.78.42.254142.78.42.255254
44142.78.43.0/24142.78.43.1 to 142.78.43.254142.78.43.255254
45142.78.44.0/24142.78.44.1 to 142.78.44.254142.78.44.255254
46142.78.45.0/24142.78.45.1 to 142.78.45.254142.78.45.255254
47142.78.46.0/24142.78.46.1 to 142.78.46.254142.78.46.255254
48142.78.47.0/24142.78.47.1 to 142.78.47.254142.78.47.255254
49142.78.48.0/24142.78.48.1 to 142.78.48.254142.78.48.255254
50142.78.49.0/24142.78.49.1 to 142.78.49.254142.78.49.255254
51142.78.50.0/24142.78.50.1 to 142.78.50.254142.78.50.255254
52142.78.51.0/24142.78.51.1 to 142.78.51.254142.78.51.255254
53142.78.52.0/24142.78.52.1 to 142.78.52.254142.78.52.255254
54142.78.53.0/24142.78.53.1 to 142.78.53.254142.78.53.255254
55142.78.54.0/24142.78.54.1 to 142.78.54.254142.78.54.255254
56142.78.55.0/24142.78.55.1 to 142.78.55.254142.78.55.255254
57142.78.56.0/24142.78.56.1 to 142.78.56.254142.78.56.255254
58142.78.57.0/24142.78.57.1 to 142.78.57.254142.78.57.255254
59142.78.58.0/24142.78.58.1 to 142.78.58.254142.78.58.255254
60142.78.59.0/24142.78.59.1 to 142.78.59.254142.78.59.255254
61142.78.60.0/24142.78.60.1 to 142.78.60.254142.78.60.255254
62142.78.61.0/24142.78.61.1 to 142.78.61.254142.78.61.255254
63142.78.62.0/24142.78.62.1 to 142.78.62.254142.78.62.255254
64142.78.63.0/24142.78.63.1 to 142.78.63.254142.78.63.255254
65142.78.64.0/24142.78.64.1 to 142.78.64.254142.78.64.255254
66142.78.65.0/24142.78.65.1 to 142.78.65.254142.78.65.255254
67142.78.66.0/24142.78.66.1 to 142.78.66.254142.78.66.255254
68142.78.67.0/24142.78.67.1 to 142.78.67.254142.78.67.255254
69142.78.68.0/24142.78.68.1 to 142.78.68.254142.78.68.255254
70142.78.69.0/24142.78.69.1 to 142.78.69.254142.78.69.255254
71142.78.70.0/24142.78.70.1 to 142.78.70.254142.78.70.255254
72142.78.71.0/24142.78.71.1 to 142.78.71.254142.78.71.255254
73142.78.72.0/24142.78.72.1 to 142.78.72.254142.78.72.255254
74142.78.73.0/24142.78.73.1 to 142.78.73.254142.78.73.255254
75142.78.74.0/24142.78.74.1 to 142.78.74.254142.78.74.255254
76142.78.75.0/24142.78.75.1 to 142.78.75.254142.78.75.255254
77142.78.76.0/24142.78.76.1 to 142.78.76.254142.78.76.255254
78142.78.77.0/24142.78.77.1 to 142.78.77.254142.78.77.255254
79142.78.78.0/24142.78.78.1 to 142.78.78.254142.78.78.255254
80142.78.79.0/24142.78.79.1 to 142.78.79.254142.78.79.255254
81142.78.80.0/24142.78.80.1 to 142.78.80.254142.78.80.255254
82142.78.81.0/24142.78.81.1 to 142.78.81.254142.78.81.255254
83142.78.82.0/24142.78.82.1 to 142.78.82.254142.78.82.255254
84142.78.83.0/24142.78.83.1 to 142.78.83.254142.78.83.255254
85142.78.84.0/24142.78.84.1 to 142.78.84.254142.78.84.255254
86142.78.85.0/24142.78.85.1 to 142.78.85.254142.78.85.255254
87142.78.86.0/24142.78.86.1 to 142.78.86.254142.78.86.255254
88142.78.87.0/24142.78.87.1 to 142.78.87.254142.78.87.255254
89142.78.88.0/24142.78.88.1 to 142.78.88.254142.78.88.255254
90142.78.89.0/24142.78.89.1 to 142.78.89.254142.78.89.255254
91142.78.90.0/24142.78.90.1 to 142.78.90.254142.78.90.255254
92142.78.91.0/24142.78.91.1 to 142.78.91.254142.78.91.255254
93142.78.92.0/24142.78.92.1 to 142.78.92.254142.78.92.255254
94142.78.93.0/24142.78.93.1 to 142.78.93.254142.78.93.255254
95142.78.94.0/24142.78.94.1 to 142.78.94.254142.78.94.255254
96142.78.95.0/24142.78.95.1 to 142.78.95.254142.78.95.255254
97142.78.96.0/24142.78.96.1 to 142.78.96.254142.78.96.255254
98142.78.97.0/24142.78.97.1 to 142.78.97.254142.78.97.255254
99142.78.98.0/24142.78.98.1 to 142.78.98.254142.78.98.255254
100142.78.99.0/24142.78.99.1 to 142.78.99.254142.78.99.255254
101142.78.100.0/24142.78.100.1 to 142.78.100.254142.78.100.255254
102142.78.101.0/24142.78.101.1 to 142.78.101.254142.78.101.255254
103142.78.102.0/24142.78.102.1 to 142.78.102.254142.78.102.255254
104142.78.103.0/24142.78.103.1 to 142.78.103.254142.78.103.255254
105142.78.104.0/24142.78.104.1 to 142.78.104.254142.78.104.255254
106142.78.105.0/24142.78.105.1 to 142.78.105.254142.78.105.255254
107142.78.106.0/24142.78.106.1 to 142.78.106.254142.78.106.255254
108142.78.107.0/24142.78.107.1 to 142.78.107.254142.78.107.255254
109142.78.108.0/24142.78.108.1 to 142.78.108.254142.78.108.255254
110142.78.109.0/24142.78.109.1 to 142.78.109.254142.78.109.255254
111142.78.110.0/24142.78.110.1 to 142.78.110.254142.78.110.255254
112142.78.111.0/24142.78.111.1 to 142.78.111.254142.78.111.255254
113142.78.112.0/24142.78.112.1 to 142.78.112.254142.78.112.255254
114142.78.113.0/24142.78.113.1 to 142.78.113.254142.78.113.255254
115142.78.114.0/24142.78.114.1 to 142.78.114.254142.78.114.255254
116142.78.115.0/24142.78.115.1 to 142.78.115.254142.78.115.255254
117142.78.116.0/24142.78.116.1 to 142.78.116.254142.78.116.255254
118142.78.117.0/24142.78.117.1 to 142.78.117.254142.78.117.255254
119142.78.118.0/24142.78.118.1 to 142.78.118.254142.78.118.255254
120142.78.119.0/24142.78.119.1 to 142.78.119.254142.78.119.255254
121142.78.120.0/24142.78.120.1 to 142.78.120.254142.78.120.255254
122142.78.121.0/24142.78.121.1 to 142.78.121.254142.78.121.255254
123142.78.122.0/24142.78.122.1 to 142.78.122.254142.78.122.255254
124142.78.123.0/24142.78.123.1 to 142.78.123.254142.78.123.255254
125142.78.124.0/24142.78.124.1 to 142.78.124.254142.78.124.255254
126142.78.125.0/24142.78.125.1 to 142.78.125.254142.78.125.255254
127142.78.126.0/24142.78.126.1 to 142.78.126.254142.78.126.255254
128142.78.127.0/24142.78.127.1 to 142.78.127.254142.78.127.255254

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