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.

Network17.64.0.0/11
Usable hosts2,097,150
Subnet mask255.224.0.0
Addresses2,097,152
Network address
17.64.0.0
Broadcast address
17.95.255.255
First usable
17.64.0.1
Last usable
17.95.255.254
Usable hosts
2,097,150 (2,097,152 less the network and broadcast addresses)
Subnet mask
255.224.0.0
Wildcard mask
0.31.255.255 (Cisco ACLs, OSPF)
Prefix length
/11
Type
Public public
Old class
A (default /8)
As numbers
Hex 11400000 · Integer 289406976 to 291504127
Reverse DNS zones
64.17.in-addr.arpa
65.17.in-addr.arpa
66.17.in-addr.arpa
67.17.in-addr.arpa
68.17.in-addr.arpa
69.17.in-addr.arpa
70.17.in-addr.arpa
71.17.in-addr.arpa
72.17.in-addr.arpa
73.17.in-addr.arpa
74.17.in-addr.arpa
75.17.in-addr.arpa
76.17.in-addr.arpa
77.17.in-addr.arpa
78.17.in-addr.arpa
79.17.in-addr.arpa
and 16 more
/11 is not on a 8-bit boundary, so it takes 32 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address00010001.01000000.00000000.0000000017.64.0.0
Subnet mask11111111.11100000.00000000.00000000255.224.0.0
Network00010001.01000000.00000000.0000000017.64.0.0
Broadcast00010001.01011111.11111111.1111111117.95.255.255
Split into smaller subnets/22
/12 (2)/13 (4)/14 (8)/15 (16)/16 (32)/17 (64)/18 (128)/19 (256)/20 (512)/21 (1,024)/22 (2,048)/23 (4,096)

17.64.0.0/11 makes 2,048 subnets of /22; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
117.64.0.0/2217.64.0.1 to 17.64.3.25417.64.3.2551,022
217.64.4.0/2217.64.4.1 to 17.64.7.25417.64.7.2551,022
317.64.8.0/2217.64.8.1 to 17.64.11.25417.64.11.2551,022
417.64.12.0/2217.64.12.1 to 17.64.15.25417.64.15.2551,022
517.64.16.0/2217.64.16.1 to 17.64.19.25417.64.19.2551,022
617.64.20.0/2217.64.20.1 to 17.64.23.25417.64.23.2551,022
717.64.24.0/2217.64.24.1 to 17.64.27.25417.64.27.2551,022
817.64.28.0/2217.64.28.1 to 17.64.31.25417.64.31.2551,022
917.64.32.0/2217.64.32.1 to 17.64.35.25417.64.35.2551,022
1017.64.36.0/2217.64.36.1 to 17.64.39.25417.64.39.2551,022
1117.64.40.0/2217.64.40.1 to 17.64.43.25417.64.43.2551,022
1217.64.44.0/2217.64.44.1 to 17.64.47.25417.64.47.2551,022
1317.64.48.0/2217.64.48.1 to 17.64.51.25417.64.51.2551,022
1417.64.52.0/2217.64.52.1 to 17.64.55.25417.64.55.2551,022
1517.64.56.0/2217.64.56.1 to 17.64.59.25417.64.59.2551,022
1617.64.60.0/2217.64.60.1 to 17.64.63.25417.64.63.2551,022
1717.64.64.0/2217.64.64.1 to 17.64.67.25417.64.67.2551,022
1817.64.68.0/2217.64.68.1 to 17.64.71.25417.64.71.2551,022
1917.64.72.0/2217.64.72.1 to 17.64.75.25417.64.75.2551,022
2017.64.76.0/2217.64.76.1 to 17.64.79.25417.64.79.2551,022
2117.64.80.0/2217.64.80.1 to 17.64.83.25417.64.83.2551,022
2217.64.84.0/2217.64.84.1 to 17.64.87.25417.64.87.2551,022
2317.64.88.0/2217.64.88.1 to 17.64.91.25417.64.91.2551,022
2417.64.92.0/2217.64.92.1 to 17.64.95.25417.64.95.2551,022
2517.64.96.0/2217.64.96.1 to 17.64.99.25417.64.99.2551,022
2617.64.100.0/2217.64.100.1 to 17.64.103.25417.64.103.2551,022
2717.64.104.0/2217.64.104.1 to 17.64.107.25417.64.107.2551,022
2817.64.108.0/2217.64.108.1 to 17.64.111.25417.64.111.2551,022
2917.64.112.0/2217.64.112.1 to 17.64.115.25417.64.115.2551,022
3017.64.116.0/2217.64.116.1 to 17.64.119.25417.64.119.2551,022
3117.64.120.0/2217.64.120.1 to 17.64.123.25417.64.123.2551,022
3217.64.124.0/2217.64.124.1 to 17.64.127.25417.64.127.2551,022
3317.64.128.0/2217.64.128.1 to 17.64.131.25417.64.131.2551,022
3417.64.132.0/2217.64.132.1 to 17.64.135.25417.64.135.2551,022
3517.64.136.0/2217.64.136.1 to 17.64.139.25417.64.139.2551,022
3617.64.140.0/2217.64.140.1 to 17.64.143.25417.64.143.2551,022
3717.64.144.0/2217.64.144.1 to 17.64.147.25417.64.147.2551,022
3817.64.148.0/2217.64.148.1 to 17.64.151.25417.64.151.2551,022
3917.64.152.0/2217.64.152.1 to 17.64.155.25417.64.155.2551,022
4017.64.156.0/2217.64.156.1 to 17.64.159.25417.64.159.2551,022
4117.64.160.0/2217.64.160.1 to 17.64.163.25417.64.163.2551,022
4217.64.164.0/2217.64.164.1 to 17.64.167.25417.64.167.2551,022
4317.64.168.0/2217.64.168.1 to 17.64.171.25417.64.171.2551,022
4417.64.172.0/2217.64.172.1 to 17.64.175.25417.64.175.2551,022
4517.64.176.0/2217.64.176.1 to 17.64.179.25417.64.179.2551,022
4617.64.180.0/2217.64.180.1 to 17.64.183.25417.64.183.2551,022
4717.64.184.0/2217.64.184.1 to 17.64.187.25417.64.187.2551,022
4817.64.188.0/2217.64.188.1 to 17.64.191.25417.64.191.2551,022
4917.64.192.0/2217.64.192.1 to 17.64.195.25417.64.195.2551,022
5017.64.196.0/2217.64.196.1 to 17.64.199.25417.64.199.2551,022
5117.64.200.0/2217.64.200.1 to 17.64.203.25417.64.203.2551,022
5217.64.204.0/2217.64.204.1 to 17.64.207.25417.64.207.2551,022
5317.64.208.0/2217.64.208.1 to 17.64.211.25417.64.211.2551,022
5417.64.212.0/2217.64.212.1 to 17.64.215.25417.64.215.2551,022
5517.64.216.0/2217.64.216.1 to 17.64.219.25417.64.219.2551,022
5617.64.220.0/2217.64.220.1 to 17.64.223.25417.64.223.2551,022
5717.64.224.0/2217.64.224.1 to 17.64.227.25417.64.227.2551,022
5817.64.228.0/2217.64.228.1 to 17.64.231.25417.64.231.2551,022
5917.64.232.0/2217.64.232.1 to 17.64.235.25417.64.235.2551,022
6017.64.236.0/2217.64.236.1 to 17.64.239.25417.64.239.2551,022
6117.64.240.0/2217.64.240.1 to 17.64.243.25417.64.243.2551,022
6217.64.244.0/2217.64.244.1 to 17.64.247.25417.64.247.2551,022
6317.64.248.0/2217.64.248.1 to 17.64.251.25417.64.251.2551,022
6417.64.252.0/2217.64.252.1 to 17.64.255.25417.64.255.2551,022
6517.65.0.0/2217.65.0.1 to 17.65.3.25417.65.3.2551,022
6617.65.4.0/2217.65.4.1 to 17.65.7.25417.65.7.2551,022
6717.65.8.0/2217.65.8.1 to 17.65.11.25417.65.11.2551,022
6817.65.12.0/2217.65.12.1 to 17.65.15.25417.65.15.2551,022
6917.65.16.0/2217.65.16.1 to 17.65.19.25417.65.19.2551,022
7017.65.20.0/2217.65.20.1 to 17.65.23.25417.65.23.2551,022
7117.65.24.0/2217.65.24.1 to 17.65.27.25417.65.27.2551,022
7217.65.28.0/2217.65.28.1 to 17.65.31.25417.65.31.2551,022
7317.65.32.0/2217.65.32.1 to 17.65.35.25417.65.35.2551,022
7417.65.36.0/2217.65.36.1 to 17.65.39.25417.65.39.2551,022
7517.65.40.0/2217.65.40.1 to 17.65.43.25417.65.43.2551,022
7617.65.44.0/2217.65.44.1 to 17.65.47.25417.65.47.2551,022
7717.65.48.0/2217.65.48.1 to 17.65.51.25417.65.51.2551,022
7817.65.52.0/2217.65.52.1 to 17.65.55.25417.65.55.2551,022
7917.65.56.0/2217.65.56.1 to 17.65.59.25417.65.59.2551,022
8017.65.60.0/2217.65.60.1 to 17.65.63.25417.65.63.2551,022
8117.65.64.0/2217.65.64.1 to 17.65.67.25417.65.67.2551,022
8217.65.68.0/2217.65.68.1 to 17.65.71.25417.65.71.2551,022
8317.65.72.0/2217.65.72.1 to 17.65.75.25417.65.75.2551,022
8417.65.76.0/2217.65.76.1 to 17.65.79.25417.65.79.2551,022
8517.65.80.0/2217.65.80.1 to 17.65.83.25417.65.83.2551,022
8617.65.84.0/2217.65.84.1 to 17.65.87.25417.65.87.2551,022
8717.65.88.0/2217.65.88.1 to 17.65.91.25417.65.91.2551,022
8817.65.92.0/2217.65.92.1 to 17.65.95.25417.65.95.2551,022
8917.65.96.0/2217.65.96.1 to 17.65.99.25417.65.99.2551,022
9017.65.100.0/2217.65.100.1 to 17.65.103.25417.65.103.2551,022
9117.65.104.0/2217.65.104.1 to 17.65.107.25417.65.107.2551,022
9217.65.108.0/2217.65.108.1 to 17.65.111.25417.65.111.2551,022
9317.65.112.0/2217.65.112.1 to 17.65.115.25417.65.115.2551,022
9417.65.116.0/2217.65.116.1 to 17.65.119.25417.65.119.2551,022
9517.65.120.0/2217.65.120.1 to 17.65.123.25417.65.123.2551,022
9617.65.124.0/2217.65.124.1 to 17.65.127.25417.65.127.2551,022
9717.65.128.0/2217.65.128.1 to 17.65.131.25417.65.131.2551,022
9817.65.132.0/2217.65.132.1 to 17.65.135.25417.65.135.2551,022
9917.65.136.0/2217.65.136.1 to 17.65.139.25417.65.139.2551,022
10017.65.140.0/2217.65.140.1 to 17.65.143.25417.65.143.2551,022
10117.65.144.0/2217.65.144.1 to 17.65.147.25417.65.147.2551,022
10217.65.148.0/2217.65.148.1 to 17.65.151.25417.65.151.2551,022
10317.65.152.0/2217.65.152.1 to 17.65.155.25417.65.155.2551,022
10417.65.156.0/2217.65.156.1 to 17.65.159.25417.65.159.2551,022
10517.65.160.0/2217.65.160.1 to 17.65.163.25417.65.163.2551,022
10617.65.164.0/2217.65.164.1 to 17.65.167.25417.65.167.2551,022
10717.65.168.0/2217.65.168.1 to 17.65.171.25417.65.171.2551,022
10817.65.172.0/2217.65.172.1 to 17.65.175.25417.65.175.2551,022
10917.65.176.0/2217.65.176.1 to 17.65.179.25417.65.179.2551,022
11017.65.180.0/2217.65.180.1 to 17.65.183.25417.65.183.2551,022
11117.65.184.0/2217.65.184.1 to 17.65.187.25417.65.187.2551,022
11217.65.188.0/2217.65.188.1 to 17.65.191.25417.65.191.2551,022
11317.65.192.0/2217.65.192.1 to 17.65.195.25417.65.195.2551,022
11417.65.196.0/2217.65.196.1 to 17.65.199.25417.65.199.2551,022
11517.65.200.0/2217.65.200.1 to 17.65.203.25417.65.203.2551,022
11617.65.204.0/2217.65.204.1 to 17.65.207.25417.65.207.2551,022
11717.65.208.0/2217.65.208.1 to 17.65.211.25417.65.211.2551,022
11817.65.212.0/2217.65.212.1 to 17.65.215.25417.65.215.2551,022
11917.65.216.0/2217.65.216.1 to 17.65.219.25417.65.219.2551,022
12017.65.220.0/2217.65.220.1 to 17.65.223.25417.65.223.2551,022
12117.65.224.0/2217.65.224.1 to 17.65.227.25417.65.227.2551,022
12217.65.228.0/2217.65.228.1 to 17.65.231.25417.65.231.2551,022
12317.65.232.0/2217.65.232.1 to 17.65.235.25417.65.235.2551,022
12417.65.236.0/2217.65.236.1 to 17.65.239.25417.65.239.2551,022
12517.65.240.0/2217.65.240.1 to 17.65.243.25417.65.243.2551,022
12617.65.244.0/2217.65.244.1 to 17.65.247.25417.65.247.2551,022
12717.65.248.0/2217.65.248.1 to 17.65.251.25417.65.251.2551,022
12817.65.252.0/2217.65.252.1 to 17.65.255.25417.65.255.2551,022
12917.66.0.0/2217.66.0.1 to 17.66.3.25417.66.3.2551,022
13017.66.4.0/2217.66.4.1 to 17.66.7.25417.66.7.2551,022
13117.66.8.0/2217.66.8.1 to 17.66.11.25417.66.11.2551,022
13217.66.12.0/2217.66.12.1 to 17.66.15.25417.66.15.2551,022
13317.66.16.0/2217.66.16.1 to 17.66.19.25417.66.19.2551,022
13417.66.20.0/2217.66.20.1 to 17.66.23.25417.66.23.2551,022
13517.66.24.0/2217.66.24.1 to 17.66.27.25417.66.27.2551,022
13617.66.28.0/2217.66.28.1 to 17.66.31.25417.66.31.2551,022
13717.66.32.0/2217.66.32.1 to 17.66.35.25417.66.35.2551,022
13817.66.36.0/2217.66.36.1 to 17.66.39.25417.66.39.2551,022
13917.66.40.0/2217.66.40.1 to 17.66.43.25417.66.43.2551,022
14017.66.44.0/2217.66.44.1 to 17.66.47.25417.66.47.2551,022
14117.66.48.0/2217.66.48.1 to 17.66.51.25417.66.51.2551,022
14217.66.52.0/2217.66.52.1 to 17.66.55.25417.66.55.2551,022
14317.66.56.0/2217.66.56.1 to 17.66.59.25417.66.59.2551,022
14417.66.60.0/2217.66.60.1 to 17.66.63.25417.66.63.2551,022
14517.66.64.0/2217.66.64.1 to 17.66.67.25417.66.67.2551,022
14617.66.68.0/2217.66.68.1 to 17.66.71.25417.66.71.2551,022
14717.66.72.0/2217.66.72.1 to 17.66.75.25417.66.75.2551,022
14817.66.76.0/2217.66.76.1 to 17.66.79.25417.66.79.2551,022
14917.66.80.0/2217.66.80.1 to 17.66.83.25417.66.83.2551,022
15017.66.84.0/2217.66.84.1 to 17.66.87.25417.66.87.2551,022
15117.66.88.0/2217.66.88.1 to 17.66.91.25417.66.91.2551,022
15217.66.92.0/2217.66.92.1 to 17.66.95.25417.66.95.2551,022
15317.66.96.0/2217.66.96.1 to 17.66.99.25417.66.99.2551,022
15417.66.100.0/2217.66.100.1 to 17.66.103.25417.66.103.2551,022
15517.66.104.0/2217.66.104.1 to 17.66.107.25417.66.107.2551,022
15617.66.108.0/2217.66.108.1 to 17.66.111.25417.66.111.2551,022
15717.66.112.0/2217.66.112.1 to 17.66.115.25417.66.115.2551,022
15817.66.116.0/2217.66.116.1 to 17.66.119.25417.66.119.2551,022
15917.66.120.0/2217.66.120.1 to 17.66.123.25417.66.123.2551,022
16017.66.124.0/2217.66.124.1 to 17.66.127.25417.66.127.2551,022
16117.66.128.0/2217.66.128.1 to 17.66.131.25417.66.131.2551,022
16217.66.132.0/2217.66.132.1 to 17.66.135.25417.66.135.2551,022
16317.66.136.0/2217.66.136.1 to 17.66.139.25417.66.139.2551,022
16417.66.140.0/2217.66.140.1 to 17.66.143.25417.66.143.2551,022
16517.66.144.0/2217.66.144.1 to 17.66.147.25417.66.147.2551,022
16617.66.148.0/2217.66.148.1 to 17.66.151.25417.66.151.2551,022
16717.66.152.0/2217.66.152.1 to 17.66.155.25417.66.155.2551,022
16817.66.156.0/2217.66.156.1 to 17.66.159.25417.66.159.2551,022
16917.66.160.0/2217.66.160.1 to 17.66.163.25417.66.163.2551,022
17017.66.164.0/2217.66.164.1 to 17.66.167.25417.66.167.2551,022
17117.66.168.0/2217.66.168.1 to 17.66.171.25417.66.171.2551,022
17217.66.172.0/2217.66.172.1 to 17.66.175.25417.66.175.2551,022
17317.66.176.0/2217.66.176.1 to 17.66.179.25417.66.179.2551,022
17417.66.180.0/2217.66.180.1 to 17.66.183.25417.66.183.2551,022
17517.66.184.0/2217.66.184.1 to 17.66.187.25417.66.187.2551,022
17617.66.188.0/2217.66.188.1 to 17.66.191.25417.66.191.2551,022
17717.66.192.0/2217.66.192.1 to 17.66.195.25417.66.195.2551,022
17817.66.196.0/2217.66.196.1 to 17.66.199.25417.66.199.2551,022
17917.66.200.0/2217.66.200.1 to 17.66.203.25417.66.203.2551,022
18017.66.204.0/2217.66.204.1 to 17.66.207.25417.66.207.2551,022
18117.66.208.0/2217.66.208.1 to 17.66.211.25417.66.211.2551,022
18217.66.212.0/2217.66.212.1 to 17.66.215.25417.66.215.2551,022
18317.66.216.0/2217.66.216.1 to 17.66.219.25417.66.219.2551,022
18417.66.220.0/2217.66.220.1 to 17.66.223.25417.66.223.2551,022
18517.66.224.0/2217.66.224.1 to 17.66.227.25417.66.227.2551,022
18617.66.228.0/2217.66.228.1 to 17.66.231.25417.66.231.2551,022
18717.66.232.0/2217.66.232.1 to 17.66.235.25417.66.235.2551,022
18817.66.236.0/2217.66.236.1 to 17.66.239.25417.66.239.2551,022
18917.66.240.0/2217.66.240.1 to 17.66.243.25417.66.243.2551,022
19017.66.244.0/2217.66.244.1 to 17.66.247.25417.66.247.2551,022
19117.66.248.0/2217.66.248.1 to 17.66.251.25417.66.251.2551,022
19217.66.252.0/2217.66.252.1 to 17.66.255.25417.66.255.2551,022
19317.67.0.0/2217.67.0.1 to 17.67.3.25417.67.3.2551,022
19417.67.4.0/2217.67.4.1 to 17.67.7.25417.67.7.2551,022
19517.67.8.0/2217.67.8.1 to 17.67.11.25417.67.11.2551,022
19617.67.12.0/2217.67.12.1 to 17.67.15.25417.67.15.2551,022
19717.67.16.0/2217.67.16.1 to 17.67.19.25417.67.19.2551,022
19817.67.20.0/2217.67.20.1 to 17.67.23.25417.67.23.2551,022
19917.67.24.0/2217.67.24.1 to 17.67.27.25417.67.27.2551,022
20017.67.28.0/2217.67.28.1 to 17.67.31.25417.67.31.2551,022
20117.67.32.0/2217.67.32.1 to 17.67.35.25417.67.35.2551,022
20217.67.36.0/2217.67.36.1 to 17.67.39.25417.67.39.2551,022
20317.67.40.0/2217.67.40.1 to 17.67.43.25417.67.43.2551,022
20417.67.44.0/2217.67.44.1 to 17.67.47.25417.67.47.2551,022
20517.67.48.0/2217.67.48.1 to 17.67.51.25417.67.51.2551,022
20617.67.52.0/2217.67.52.1 to 17.67.55.25417.67.55.2551,022
20717.67.56.0/2217.67.56.1 to 17.67.59.25417.67.59.2551,022
20817.67.60.0/2217.67.60.1 to 17.67.63.25417.67.63.2551,022
20917.67.64.0/2217.67.64.1 to 17.67.67.25417.67.67.2551,022
21017.67.68.0/2217.67.68.1 to 17.67.71.25417.67.71.2551,022
21117.67.72.0/2217.67.72.1 to 17.67.75.25417.67.75.2551,022
21217.67.76.0/2217.67.76.1 to 17.67.79.25417.67.79.2551,022
21317.67.80.0/2217.67.80.1 to 17.67.83.25417.67.83.2551,022
21417.67.84.0/2217.67.84.1 to 17.67.87.25417.67.87.2551,022
21517.67.88.0/2217.67.88.1 to 17.67.91.25417.67.91.2551,022
21617.67.92.0/2217.67.92.1 to 17.67.95.25417.67.95.2551,022
21717.67.96.0/2217.67.96.1 to 17.67.99.25417.67.99.2551,022
21817.67.100.0/2217.67.100.1 to 17.67.103.25417.67.103.2551,022
21917.67.104.0/2217.67.104.1 to 17.67.107.25417.67.107.2551,022
22017.67.108.0/2217.67.108.1 to 17.67.111.25417.67.111.2551,022
22117.67.112.0/2217.67.112.1 to 17.67.115.25417.67.115.2551,022
22217.67.116.0/2217.67.116.1 to 17.67.119.25417.67.119.2551,022
22317.67.120.0/2217.67.120.1 to 17.67.123.25417.67.123.2551,022
22417.67.124.0/2217.67.124.1 to 17.67.127.25417.67.127.2551,022
22517.67.128.0/2217.67.128.1 to 17.67.131.25417.67.131.2551,022
22617.67.132.0/2217.67.132.1 to 17.67.135.25417.67.135.2551,022
22717.67.136.0/2217.67.136.1 to 17.67.139.25417.67.139.2551,022
22817.67.140.0/2217.67.140.1 to 17.67.143.25417.67.143.2551,022
22917.67.144.0/2217.67.144.1 to 17.67.147.25417.67.147.2551,022
23017.67.148.0/2217.67.148.1 to 17.67.151.25417.67.151.2551,022
23117.67.152.0/2217.67.152.1 to 17.67.155.25417.67.155.2551,022
23217.67.156.0/2217.67.156.1 to 17.67.159.25417.67.159.2551,022
23317.67.160.0/2217.67.160.1 to 17.67.163.25417.67.163.2551,022
23417.67.164.0/2217.67.164.1 to 17.67.167.25417.67.167.2551,022
23517.67.168.0/2217.67.168.1 to 17.67.171.25417.67.171.2551,022
23617.67.172.0/2217.67.172.1 to 17.67.175.25417.67.175.2551,022
23717.67.176.0/2217.67.176.1 to 17.67.179.25417.67.179.2551,022
23817.67.180.0/2217.67.180.1 to 17.67.183.25417.67.183.2551,022
23917.67.184.0/2217.67.184.1 to 17.67.187.25417.67.187.2551,022
24017.67.188.0/2217.67.188.1 to 17.67.191.25417.67.191.2551,022
24117.67.192.0/2217.67.192.1 to 17.67.195.25417.67.195.2551,022
24217.67.196.0/2217.67.196.1 to 17.67.199.25417.67.199.2551,022
24317.67.200.0/2217.67.200.1 to 17.67.203.25417.67.203.2551,022
24417.67.204.0/2217.67.204.1 to 17.67.207.25417.67.207.2551,022
24517.67.208.0/2217.67.208.1 to 17.67.211.25417.67.211.2551,022
24617.67.212.0/2217.67.212.1 to 17.67.215.25417.67.215.2551,022
24717.67.216.0/2217.67.216.1 to 17.67.219.25417.67.219.2551,022
24817.67.220.0/2217.67.220.1 to 17.67.223.25417.67.223.2551,022
24917.67.224.0/2217.67.224.1 to 17.67.227.25417.67.227.2551,022
25017.67.228.0/2217.67.228.1 to 17.67.231.25417.67.231.2551,022
25117.67.232.0/2217.67.232.1 to 17.67.235.25417.67.235.2551,022
25217.67.236.0/2217.67.236.1 to 17.67.239.25417.67.239.2551,022
25317.67.240.0/2217.67.240.1 to 17.67.243.25417.67.243.2551,022
25417.67.244.0/2217.67.244.1 to 17.67.247.25417.67.247.2551,022
25517.67.248.0/2217.67.248.1 to 17.67.251.25417.67.251.2551,022
25617.67.252.0/2217.67.252.1 to 17.67.255.25417.67.255.2551,022

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.