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.

Network104.28.0.0/14
Usable hosts262,142
Subnet mask255.252.0.0
Addresses262,144
Network address
104.28.0.0
Broadcast address
104.31.255.255
First usable
104.28.0.1
Last usable
104.31.255.254
Usable hosts
262,142 (262,144 less the network and broadcast addresses)
Subnet mask
255.252.0.0
Wildcard mask
0.3.255.255 (Cisco ACLs, OSPF)
Prefix length
/14
Type
Public public
Old class
A (default /8)
As numbers
Hex 681C0000 · Integer 1746665472 to 1746927615
Reverse DNS zones
28.104.in-addr.arpa
29.104.in-addr.arpa
30.104.in-addr.arpa
31.104.in-addr.arpa
/14 is not on a 8-bit boundary, so it takes 4 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01101000.00011100.00000000.00000000104.28.0.0
Subnet mask11111111.11111100.00000000.00000000255.252.0.0
Network01101000.00011100.00000000.00000000104.28.0.0
Broadcast01101000.00011111.11111111.11111111104.31.255.255
Split into smaller subnets/22
/15 (2)/16 (4)/17 (8)/18 (16)/19 (32)/20 (64)/21 (128)/22 (256)/23 (512)/24 (1,024)/25 (2,048)/26 (4,096)

104.28.0.0/14 makes 256 subnets of /22.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1104.28.0.0/22104.28.0.1 to 104.28.3.254104.28.3.2551,022
2104.28.4.0/22104.28.4.1 to 104.28.7.254104.28.7.2551,022
3104.28.8.0/22104.28.8.1 to 104.28.11.254104.28.11.2551,022
4104.28.12.0/22104.28.12.1 to 104.28.15.254104.28.15.2551,022
5104.28.16.0/22104.28.16.1 to 104.28.19.254104.28.19.2551,022
6104.28.20.0/22104.28.20.1 to 104.28.23.254104.28.23.2551,022
7104.28.24.0/22104.28.24.1 to 104.28.27.254104.28.27.2551,022
8104.28.28.0/22104.28.28.1 to 104.28.31.254104.28.31.2551,022
9104.28.32.0/22104.28.32.1 to 104.28.35.254104.28.35.2551,022
10104.28.36.0/22104.28.36.1 to 104.28.39.254104.28.39.2551,022
11104.28.40.0/22104.28.40.1 to 104.28.43.254104.28.43.2551,022
12104.28.44.0/22104.28.44.1 to 104.28.47.254104.28.47.2551,022
13104.28.48.0/22104.28.48.1 to 104.28.51.254104.28.51.2551,022
14104.28.52.0/22104.28.52.1 to 104.28.55.254104.28.55.2551,022
15104.28.56.0/22104.28.56.1 to 104.28.59.254104.28.59.2551,022
16104.28.60.0/22104.28.60.1 to 104.28.63.254104.28.63.2551,022
17104.28.64.0/22104.28.64.1 to 104.28.67.254104.28.67.2551,022
18104.28.68.0/22104.28.68.1 to 104.28.71.254104.28.71.2551,022
19104.28.72.0/22104.28.72.1 to 104.28.75.254104.28.75.2551,022
20104.28.76.0/22104.28.76.1 to 104.28.79.254104.28.79.2551,022
21104.28.80.0/22104.28.80.1 to 104.28.83.254104.28.83.2551,022
22104.28.84.0/22104.28.84.1 to 104.28.87.254104.28.87.2551,022
23104.28.88.0/22104.28.88.1 to 104.28.91.254104.28.91.2551,022
24104.28.92.0/22104.28.92.1 to 104.28.95.254104.28.95.2551,022
25104.28.96.0/22104.28.96.1 to 104.28.99.254104.28.99.2551,022
26104.28.100.0/22104.28.100.1 to 104.28.103.254104.28.103.2551,022
27104.28.104.0/22104.28.104.1 to 104.28.107.254104.28.107.2551,022
28104.28.108.0/22104.28.108.1 to 104.28.111.254104.28.111.2551,022
29104.28.112.0/22104.28.112.1 to 104.28.115.254104.28.115.2551,022
30104.28.116.0/22104.28.116.1 to 104.28.119.254104.28.119.2551,022
31104.28.120.0/22104.28.120.1 to 104.28.123.254104.28.123.2551,022
32104.28.124.0/22104.28.124.1 to 104.28.127.254104.28.127.2551,022
33104.28.128.0/22104.28.128.1 to 104.28.131.254104.28.131.2551,022
34104.28.132.0/22104.28.132.1 to 104.28.135.254104.28.135.2551,022
35104.28.136.0/22104.28.136.1 to 104.28.139.254104.28.139.2551,022
36104.28.140.0/22104.28.140.1 to 104.28.143.254104.28.143.2551,022
37104.28.144.0/22104.28.144.1 to 104.28.147.254104.28.147.2551,022
38104.28.148.0/22104.28.148.1 to 104.28.151.254104.28.151.2551,022
39104.28.152.0/22104.28.152.1 to 104.28.155.254104.28.155.2551,022
40104.28.156.0/22104.28.156.1 to 104.28.159.254104.28.159.2551,022
41104.28.160.0/22104.28.160.1 to 104.28.163.254104.28.163.2551,022
42104.28.164.0/22104.28.164.1 to 104.28.167.254104.28.167.2551,022
43104.28.168.0/22104.28.168.1 to 104.28.171.254104.28.171.2551,022
44104.28.172.0/22104.28.172.1 to 104.28.175.254104.28.175.2551,022
45104.28.176.0/22104.28.176.1 to 104.28.179.254104.28.179.2551,022
46104.28.180.0/22104.28.180.1 to 104.28.183.254104.28.183.2551,022
47104.28.184.0/22104.28.184.1 to 104.28.187.254104.28.187.2551,022
48104.28.188.0/22104.28.188.1 to 104.28.191.254104.28.191.2551,022
49104.28.192.0/22104.28.192.1 to 104.28.195.254104.28.195.2551,022
50104.28.196.0/22104.28.196.1 to 104.28.199.254104.28.199.2551,022
51104.28.200.0/22104.28.200.1 to 104.28.203.254104.28.203.2551,022
52104.28.204.0/22104.28.204.1 to 104.28.207.254104.28.207.2551,022
53104.28.208.0/22104.28.208.1 to 104.28.211.254104.28.211.2551,022
54104.28.212.0/22104.28.212.1 to 104.28.215.254104.28.215.2551,022
55104.28.216.0/22104.28.216.1 to 104.28.219.254104.28.219.2551,022
56104.28.220.0/22104.28.220.1 to 104.28.223.254104.28.223.2551,022
57104.28.224.0/22104.28.224.1 to 104.28.227.254104.28.227.2551,022
58104.28.228.0/22104.28.228.1 to 104.28.231.254104.28.231.2551,022
59104.28.232.0/22104.28.232.1 to 104.28.235.254104.28.235.2551,022
60104.28.236.0/22104.28.236.1 to 104.28.239.254104.28.239.2551,022
61104.28.240.0/22104.28.240.1 to 104.28.243.254104.28.243.2551,022
62104.28.244.0/22104.28.244.1 to 104.28.247.254104.28.247.2551,022
63104.28.248.0/22104.28.248.1 to 104.28.251.254104.28.251.2551,022
64104.28.252.0/22104.28.252.1 to 104.28.255.254104.28.255.2551,022
65104.29.0.0/22104.29.0.1 to 104.29.3.254104.29.3.2551,022
66104.29.4.0/22104.29.4.1 to 104.29.7.254104.29.7.2551,022
67104.29.8.0/22104.29.8.1 to 104.29.11.254104.29.11.2551,022
68104.29.12.0/22104.29.12.1 to 104.29.15.254104.29.15.2551,022
69104.29.16.0/22104.29.16.1 to 104.29.19.254104.29.19.2551,022
70104.29.20.0/22104.29.20.1 to 104.29.23.254104.29.23.2551,022
71104.29.24.0/22104.29.24.1 to 104.29.27.254104.29.27.2551,022
72104.29.28.0/22104.29.28.1 to 104.29.31.254104.29.31.2551,022
73104.29.32.0/22104.29.32.1 to 104.29.35.254104.29.35.2551,022
74104.29.36.0/22104.29.36.1 to 104.29.39.254104.29.39.2551,022
75104.29.40.0/22104.29.40.1 to 104.29.43.254104.29.43.2551,022
76104.29.44.0/22104.29.44.1 to 104.29.47.254104.29.47.2551,022
77104.29.48.0/22104.29.48.1 to 104.29.51.254104.29.51.2551,022
78104.29.52.0/22104.29.52.1 to 104.29.55.254104.29.55.2551,022
79104.29.56.0/22104.29.56.1 to 104.29.59.254104.29.59.2551,022
80104.29.60.0/22104.29.60.1 to 104.29.63.254104.29.63.2551,022
81104.29.64.0/22104.29.64.1 to 104.29.67.254104.29.67.2551,022
82104.29.68.0/22104.29.68.1 to 104.29.71.254104.29.71.2551,022
83104.29.72.0/22104.29.72.1 to 104.29.75.254104.29.75.2551,022
84104.29.76.0/22104.29.76.1 to 104.29.79.254104.29.79.2551,022
85104.29.80.0/22104.29.80.1 to 104.29.83.254104.29.83.2551,022
86104.29.84.0/22104.29.84.1 to 104.29.87.254104.29.87.2551,022
87104.29.88.0/22104.29.88.1 to 104.29.91.254104.29.91.2551,022
88104.29.92.0/22104.29.92.1 to 104.29.95.254104.29.95.2551,022
89104.29.96.0/22104.29.96.1 to 104.29.99.254104.29.99.2551,022
90104.29.100.0/22104.29.100.1 to 104.29.103.254104.29.103.2551,022
91104.29.104.0/22104.29.104.1 to 104.29.107.254104.29.107.2551,022
92104.29.108.0/22104.29.108.1 to 104.29.111.254104.29.111.2551,022
93104.29.112.0/22104.29.112.1 to 104.29.115.254104.29.115.2551,022
94104.29.116.0/22104.29.116.1 to 104.29.119.254104.29.119.2551,022
95104.29.120.0/22104.29.120.1 to 104.29.123.254104.29.123.2551,022
96104.29.124.0/22104.29.124.1 to 104.29.127.254104.29.127.2551,022
97104.29.128.0/22104.29.128.1 to 104.29.131.254104.29.131.2551,022
98104.29.132.0/22104.29.132.1 to 104.29.135.254104.29.135.2551,022
99104.29.136.0/22104.29.136.1 to 104.29.139.254104.29.139.2551,022
100104.29.140.0/22104.29.140.1 to 104.29.143.254104.29.143.2551,022
101104.29.144.0/22104.29.144.1 to 104.29.147.254104.29.147.2551,022
102104.29.148.0/22104.29.148.1 to 104.29.151.254104.29.151.2551,022
103104.29.152.0/22104.29.152.1 to 104.29.155.254104.29.155.2551,022
104104.29.156.0/22104.29.156.1 to 104.29.159.254104.29.159.2551,022
105104.29.160.0/22104.29.160.1 to 104.29.163.254104.29.163.2551,022
106104.29.164.0/22104.29.164.1 to 104.29.167.254104.29.167.2551,022
107104.29.168.0/22104.29.168.1 to 104.29.171.254104.29.171.2551,022
108104.29.172.0/22104.29.172.1 to 104.29.175.254104.29.175.2551,022
109104.29.176.0/22104.29.176.1 to 104.29.179.254104.29.179.2551,022
110104.29.180.0/22104.29.180.1 to 104.29.183.254104.29.183.2551,022
111104.29.184.0/22104.29.184.1 to 104.29.187.254104.29.187.2551,022
112104.29.188.0/22104.29.188.1 to 104.29.191.254104.29.191.2551,022
113104.29.192.0/22104.29.192.1 to 104.29.195.254104.29.195.2551,022
114104.29.196.0/22104.29.196.1 to 104.29.199.254104.29.199.2551,022
115104.29.200.0/22104.29.200.1 to 104.29.203.254104.29.203.2551,022
116104.29.204.0/22104.29.204.1 to 104.29.207.254104.29.207.2551,022
117104.29.208.0/22104.29.208.1 to 104.29.211.254104.29.211.2551,022
118104.29.212.0/22104.29.212.1 to 104.29.215.254104.29.215.2551,022
119104.29.216.0/22104.29.216.1 to 104.29.219.254104.29.219.2551,022
120104.29.220.0/22104.29.220.1 to 104.29.223.254104.29.223.2551,022
121104.29.224.0/22104.29.224.1 to 104.29.227.254104.29.227.2551,022
122104.29.228.0/22104.29.228.1 to 104.29.231.254104.29.231.2551,022
123104.29.232.0/22104.29.232.1 to 104.29.235.254104.29.235.2551,022
124104.29.236.0/22104.29.236.1 to 104.29.239.254104.29.239.2551,022
125104.29.240.0/22104.29.240.1 to 104.29.243.254104.29.243.2551,022
126104.29.244.0/22104.29.244.1 to 104.29.247.254104.29.247.2551,022
127104.29.248.0/22104.29.248.1 to 104.29.251.254104.29.251.2551,022
128104.29.252.0/22104.29.252.1 to 104.29.255.254104.29.255.2551,022
129104.30.0.0/22104.30.0.1 to 104.30.3.254104.30.3.2551,022
130104.30.4.0/22104.30.4.1 to 104.30.7.254104.30.7.2551,022
131104.30.8.0/22104.30.8.1 to 104.30.11.254104.30.11.2551,022
132104.30.12.0/22104.30.12.1 to 104.30.15.254104.30.15.2551,022
133104.30.16.0/22104.30.16.1 to 104.30.19.254104.30.19.2551,022
134104.30.20.0/22104.30.20.1 to 104.30.23.254104.30.23.2551,022
135104.30.24.0/22104.30.24.1 to 104.30.27.254104.30.27.2551,022
136104.30.28.0/22104.30.28.1 to 104.30.31.254104.30.31.2551,022
137104.30.32.0/22104.30.32.1 to 104.30.35.254104.30.35.2551,022
138104.30.36.0/22104.30.36.1 to 104.30.39.254104.30.39.2551,022
139104.30.40.0/22104.30.40.1 to 104.30.43.254104.30.43.2551,022
140104.30.44.0/22104.30.44.1 to 104.30.47.254104.30.47.2551,022
141104.30.48.0/22104.30.48.1 to 104.30.51.254104.30.51.2551,022
142104.30.52.0/22104.30.52.1 to 104.30.55.254104.30.55.2551,022
143104.30.56.0/22104.30.56.1 to 104.30.59.254104.30.59.2551,022
144104.30.60.0/22104.30.60.1 to 104.30.63.254104.30.63.2551,022
145104.30.64.0/22104.30.64.1 to 104.30.67.254104.30.67.2551,022
146104.30.68.0/22104.30.68.1 to 104.30.71.254104.30.71.2551,022
147104.30.72.0/22104.30.72.1 to 104.30.75.254104.30.75.2551,022
148104.30.76.0/22104.30.76.1 to 104.30.79.254104.30.79.2551,022
149104.30.80.0/22104.30.80.1 to 104.30.83.254104.30.83.2551,022
150104.30.84.0/22104.30.84.1 to 104.30.87.254104.30.87.2551,022
151104.30.88.0/22104.30.88.1 to 104.30.91.254104.30.91.2551,022
152104.30.92.0/22104.30.92.1 to 104.30.95.254104.30.95.2551,022
153104.30.96.0/22104.30.96.1 to 104.30.99.254104.30.99.2551,022
154104.30.100.0/22104.30.100.1 to 104.30.103.254104.30.103.2551,022
155104.30.104.0/22104.30.104.1 to 104.30.107.254104.30.107.2551,022
156104.30.108.0/22104.30.108.1 to 104.30.111.254104.30.111.2551,022
157104.30.112.0/22104.30.112.1 to 104.30.115.254104.30.115.2551,022
158104.30.116.0/22104.30.116.1 to 104.30.119.254104.30.119.2551,022
159104.30.120.0/22104.30.120.1 to 104.30.123.254104.30.123.2551,022
160104.30.124.0/22104.30.124.1 to 104.30.127.254104.30.127.2551,022
161104.30.128.0/22104.30.128.1 to 104.30.131.254104.30.131.2551,022
162104.30.132.0/22104.30.132.1 to 104.30.135.254104.30.135.2551,022
163104.30.136.0/22104.30.136.1 to 104.30.139.254104.30.139.2551,022
164104.30.140.0/22104.30.140.1 to 104.30.143.254104.30.143.2551,022
165104.30.144.0/22104.30.144.1 to 104.30.147.254104.30.147.2551,022
166104.30.148.0/22104.30.148.1 to 104.30.151.254104.30.151.2551,022
167104.30.152.0/22104.30.152.1 to 104.30.155.254104.30.155.2551,022
168104.30.156.0/22104.30.156.1 to 104.30.159.254104.30.159.2551,022
169104.30.160.0/22104.30.160.1 to 104.30.163.254104.30.163.2551,022
170104.30.164.0/22104.30.164.1 to 104.30.167.254104.30.167.2551,022
171104.30.168.0/22104.30.168.1 to 104.30.171.254104.30.171.2551,022
172104.30.172.0/22104.30.172.1 to 104.30.175.254104.30.175.2551,022
173104.30.176.0/22104.30.176.1 to 104.30.179.254104.30.179.2551,022
174104.30.180.0/22104.30.180.1 to 104.30.183.254104.30.183.2551,022
175104.30.184.0/22104.30.184.1 to 104.30.187.254104.30.187.2551,022
176104.30.188.0/22104.30.188.1 to 104.30.191.254104.30.191.2551,022
177104.30.192.0/22104.30.192.1 to 104.30.195.254104.30.195.2551,022
178104.30.196.0/22104.30.196.1 to 104.30.199.254104.30.199.2551,022
179104.30.200.0/22104.30.200.1 to 104.30.203.254104.30.203.2551,022
180104.30.204.0/22104.30.204.1 to 104.30.207.254104.30.207.2551,022
181104.30.208.0/22104.30.208.1 to 104.30.211.254104.30.211.2551,022
182104.30.212.0/22104.30.212.1 to 104.30.215.254104.30.215.2551,022
183104.30.216.0/22104.30.216.1 to 104.30.219.254104.30.219.2551,022
184104.30.220.0/22104.30.220.1 to 104.30.223.254104.30.223.2551,022
185104.30.224.0/22104.30.224.1 to 104.30.227.254104.30.227.2551,022
186104.30.228.0/22104.30.228.1 to 104.30.231.254104.30.231.2551,022
187104.30.232.0/22104.30.232.1 to 104.30.235.254104.30.235.2551,022
188104.30.236.0/22104.30.236.1 to 104.30.239.254104.30.239.2551,022
189104.30.240.0/22104.30.240.1 to 104.30.243.254104.30.243.2551,022
190104.30.244.0/22104.30.244.1 to 104.30.247.254104.30.247.2551,022
191104.30.248.0/22104.30.248.1 to 104.30.251.254104.30.251.2551,022
192104.30.252.0/22104.30.252.1 to 104.30.255.254104.30.255.2551,022
193104.31.0.0/22104.31.0.1 to 104.31.3.254104.31.3.2551,022
194104.31.4.0/22104.31.4.1 to 104.31.7.254104.31.7.2551,022
195104.31.8.0/22104.31.8.1 to 104.31.11.254104.31.11.2551,022
196104.31.12.0/22104.31.12.1 to 104.31.15.254104.31.15.2551,022
197104.31.16.0/22104.31.16.1 to 104.31.19.254104.31.19.2551,022
198104.31.20.0/22104.31.20.1 to 104.31.23.254104.31.23.2551,022
199104.31.24.0/22104.31.24.1 to 104.31.27.254104.31.27.2551,022
200104.31.28.0/22104.31.28.1 to 104.31.31.254104.31.31.2551,022
201104.31.32.0/22104.31.32.1 to 104.31.35.254104.31.35.2551,022
202104.31.36.0/22104.31.36.1 to 104.31.39.254104.31.39.2551,022
203104.31.40.0/22104.31.40.1 to 104.31.43.254104.31.43.2551,022
204104.31.44.0/22104.31.44.1 to 104.31.47.254104.31.47.2551,022
205104.31.48.0/22104.31.48.1 to 104.31.51.254104.31.51.2551,022
206104.31.52.0/22104.31.52.1 to 104.31.55.254104.31.55.2551,022
207104.31.56.0/22104.31.56.1 to 104.31.59.254104.31.59.2551,022
208104.31.60.0/22104.31.60.1 to 104.31.63.254104.31.63.2551,022
209104.31.64.0/22104.31.64.1 to 104.31.67.254104.31.67.2551,022
210104.31.68.0/22104.31.68.1 to 104.31.71.254104.31.71.2551,022
211104.31.72.0/22104.31.72.1 to 104.31.75.254104.31.75.2551,022
212104.31.76.0/22104.31.76.1 to 104.31.79.254104.31.79.2551,022
213104.31.80.0/22104.31.80.1 to 104.31.83.254104.31.83.2551,022
214104.31.84.0/22104.31.84.1 to 104.31.87.254104.31.87.2551,022
215104.31.88.0/22104.31.88.1 to 104.31.91.254104.31.91.2551,022
216104.31.92.0/22104.31.92.1 to 104.31.95.254104.31.95.2551,022
217104.31.96.0/22104.31.96.1 to 104.31.99.254104.31.99.2551,022
218104.31.100.0/22104.31.100.1 to 104.31.103.254104.31.103.2551,022
219104.31.104.0/22104.31.104.1 to 104.31.107.254104.31.107.2551,022
220104.31.108.0/22104.31.108.1 to 104.31.111.254104.31.111.2551,022
221104.31.112.0/22104.31.112.1 to 104.31.115.254104.31.115.2551,022
222104.31.116.0/22104.31.116.1 to 104.31.119.254104.31.119.2551,022
223104.31.120.0/22104.31.120.1 to 104.31.123.254104.31.123.2551,022
224104.31.124.0/22104.31.124.1 to 104.31.127.254104.31.127.2551,022
225104.31.128.0/22104.31.128.1 to 104.31.131.254104.31.131.2551,022
226104.31.132.0/22104.31.132.1 to 104.31.135.254104.31.135.2551,022
227104.31.136.0/22104.31.136.1 to 104.31.139.254104.31.139.2551,022
228104.31.140.0/22104.31.140.1 to 104.31.143.254104.31.143.2551,022
229104.31.144.0/22104.31.144.1 to 104.31.147.254104.31.147.2551,022
230104.31.148.0/22104.31.148.1 to 104.31.151.254104.31.151.2551,022
231104.31.152.0/22104.31.152.1 to 104.31.155.254104.31.155.2551,022
232104.31.156.0/22104.31.156.1 to 104.31.159.254104.31.159.2551,022
233104.31.160.0/22104.31.160.1 to 104.31.163.254104.31.163.2551,022
234104.31.164.0/22104.31.164.1 to 104.31.167.254104.31.167.2551,022
235104.31.168.0/22104.31.168.1 to 104.31.171.254104.31.171.2551,022
236104.31.172.0/22104.31.172.1 to 104.31.175.254104.31.175.2551,022
237104.31.176.0/22104.31.176.1 to 104.31.179.254104.31.179.2551,022
238104.31.180.0/22104.31.180.1 to 104.31.183.254104.31.183.2551,022
239104.31.184.0/22104.31.184.1 to 104.31.187.254104.31.187.2551,022
240104.31.188.0/22104.31.188.1 to 104.31.191.254104.31.191.2551,022
241104.31.192.0/22104.31.192.1 to 104.31.195.254104.31.195.2551,022
242104.31.196.0/22104.31.196.1 to 104.31.199.254104.31.199.2551,022
243104.31.200.0/22104.31.200.1 to 104.31.203.254104.31.203.2551,022
244104.31.204.0/22104.31.204.1 to 104.31.207.254104.31.207.2551,022
245104.31.208.0/22104.31.208.1 to 104.31.211.254104.31.211.2551,022
246104.31.212.0/22104.31.212.1 to 104.31.215.254104.31.215.2551,022
247104.31.216.0/22104.31.216.1 to 104.31.219.254104.31.219.2551,022
248104.31.220.0/22104.31.220.1 to 104.31.223.254104.31.223.2551,022
249104.31.224.0/22104.31.224.1 to 104.31.227.254104.31.227.2551,022
250104.31.228.0/22104.31.228.1 to 104.31.231.254104.31.231.2551,022
251104.31.232.0/22104.31.232.1 to 104.31.235.254104.31.235.2551,022
252104.31.236.0/22104.31.236.1 to 104.31.239.254104.31.239.2551,022
253104.31.240.0/22104.31.240.1 to 104.31.243.254104.31.243.2551,022
254104.31.244.0/22104.31.244.1 to 104.31.247.254104.31.247.2551,022
255104.31.248.0/22104.31.248.1 to 104.31.251.254104.31.251.2551,022
256104.31.252.0/22104.31.252.1 to 104.31.255.254104.31.255.2551,022

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.