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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.

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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.

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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/16
Addresses2^112
/64 networks2^48
Network
ffc3::/16
First address
ffc3::
Last address
ffc3:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
ffc3:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
3.c.f.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ffc3::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1ffc3::/24ffc3:ff:ffff:ffff:ffff:ffff:ffff:ffff
2ffc3:100::/24ffc3:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3ffc3:200::/24ffc3:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4ffc3:300::/24ffc3:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5ffc3:400::/24ffc3:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6ffc3:500::/24ffc3:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7ffc3:600::/24ffc3:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8ffc3:700::/24ffc3:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9ffc3:800::/24ffc3:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10ffc3:900::/24ffc3:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11ffc3:a00::/24ffc3:aff:ffff:ffff:ffff:ffff:ffff:ffff
12ffc3:b00::/24ffc3:bff:ffff:ffff:ffff:ffff:ffff:ffff
13ffc3:c00::/24ffc3:cff:ffff:ffff:ffff:ffff:ffff:ffff
14ffc3:d00::/24ffc3:dff:ffff:ffff:ffff:ffff:ffff:ffff
15ffc3:e00::/24ffc3:eff:ffff:ffff:ffff:ffff:ffff:ffff
16ffc3:f00::/24ffc3:fff:ffff:ffff:ffff:ffff:ffff:ffff
17ffc3:1000::/24ffc3:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18ffc3:1100::/24ffc3:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19ffc3:1200::/24ffc3:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20ffc3:1300::/24ffc3:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21ffc3:1400::/24ffc3:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22ffc3:1500::/24ffc3:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23ffc3:1600::/24ffc3:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24ffc3:1700::/24ffc3:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25ffc3:1800::/24ffc3:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26ffc3:1900::/24ffc3:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27ffc3:1a00::/24ffc3:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28ffc3:1b00::/24ffc3:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29ffc3:1c00::/24ffc3:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30ffc3:1d00::/24ffc3:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31ffc3:1e00::/24ffc3:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32ffc3:1f00::/24ffc3:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33ffc3:2000::/24ffc3:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34ffc3:2100::/24ffc3:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35ffc3:2200::/24ffc3:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36ffc3:2300::/24ffc3:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37ffc3:2400::/24ffc3:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38ffc3:2500::/24ffc3:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39ffc3:2600::/24ffc3:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40ffc3:2700::/24ffc3:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41ffc3:2800::/24ffc3:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42ffc3:2900::/24ffc3:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43ffc3:2a00::/24ffc3:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44ffc3:2b00::/24ffc3:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45ffc3:2c00::/24ffc3:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46ffc3:2d00::/24ffc3:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47ffc3:2e00::/24ffc3:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48ffc3:2f00::/24ffc3:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49ffc3:3000::/24ffc3:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50ffc3:3100::/24ffc3:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51ffc3:3200::/24ffc3:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52ffc3:3300::/24ffc3:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53ffc3:3400::/24ffc3:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54ffc3:3500::/24ffc3:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55ffc3:3600::/24ffc3:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56ffc3:3700::/24ffc3:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57ffc3:3800::/24ffc3:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58ffc3:3900::/24ffc3:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59ffc3:3a00::/24ffc3:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60ffc3:3b00::/24ffc3:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61ffc3:3c00::/24ffc3:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62ffc3:3d00::/24ffc3:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63ffc3:3e00::/24ffc3:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64ffc3:3f00::/24ffc3:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65ffc3:4000::/24ffc3:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66ffc3:4100::/24ffc3:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67ffc3:4200::/24ffc3:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68ffc3:4300::/24ffc3:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69ffc3:4400::/24ffc3:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70ffc3:4500::/24ffc3:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71ffc3:4600::/24ffc3:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72ffc3:4700::/24ffc3:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73ffc3:4800::/24ffc3:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74ffc3:4900::/24ffc3:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75ffc3:4a00::/24ffc3:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76ffc3:4b00::/24ffc3:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77ffc3:4c00::/24ffc3:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78ffc3:4d00::/24ffc3:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79ffc3:4e00::/24ffc3:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80ffc3:4f00::/24ffc3:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81ffc3:5000::/24ffc3:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82ffc3:5100::/24ffc3:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83ffc3:5200::/24ffc3:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84ffc3:5300::/24ffc3:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85ffc3:5400::/24ffc3:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86ffc3:5500::/24ffc3:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87ffc3:5600::/24ffc3:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88ffc3:5700::/24ffc3:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89ffc3:5800::/24ffc3:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90ffc3:5900::/24ffc3:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91ffc3:5a00::/24ffc3:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92ffc3:5b00::/24ffc3:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93ffc3:5c00::/24ffc3:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94ffc3:5d00::/24ffc3:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95ffc3:5e00::/24ffc3:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96ffc3:5f00::/24ffc3:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97ffc3:6000::/24ffc3:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98ffc3:6100::/24ffc3:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99ffc3:6200::/24ffc3:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100ffc3:6300::/24ffc3:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101ffc3:6400::/24ffc3:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102ffc3:6500::/24ffc3:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103ffc3:6600::/24ffc3:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104ffc3:6700::/24ffc3:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105ffc3:6800::/24ffc3:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106ffc3:6900::/24ffc3:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107ffc3:6a00::/24ffc3:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108ffc3:6b00::/24ffc3:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109ffc3:6c00::/24ffc3:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110ffc3:6d00::/24ffc3:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111ffc3:6e00::/24ffc3:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112ffc3:6f00::/24ffc3:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113ffc3:7000::/24ffc3:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114ffc3:7100::/24ffc3:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115ffc3:7200::/24ffc3:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116ffc3:7300::/24ffc3:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117ffc3:7400::/24ffc3:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118ffc3:7500::/24ffc3:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119ffc3:7600::/24ffc3:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120ffc3:7700::/24ffc3:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121ffc3:7800::/24ffc3:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122ffc3:7900::/24ffc3:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123ffc3:7a00::/24ffc3:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124ffc3:7b00::/24ffc3:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125ffc3:7c00::/24ffc3:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126ffc3:7d00::/24ffc3:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127ffc3:7e00::/24ffc3:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128ffc3:7f00::/24ffc3:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129ffc3:8000::/24ffc3:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130ffc3:8100::/24ffc3:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131ffc3:8200::/24ffc3:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132ffc3:8300::/24ffc3:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133ffc3:8400::/24ffc3:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134ffc3:8500::/24ffc3:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135ffc3:8600::/24ffc3:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136ffc3:8700::/24ffc3:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137ffc3:8800::/24ffc3:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138ffc3:8900::/24ffc3:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139ffc3:8a00::/24ffc3:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140ffc3:8b00::/24ffc3:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141ffc3:8c00::/24ffc3:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142ffc3:8d00::/24ffc3:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143ffc3:8e00::/24ffc3:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144ffc3:8f00::/24ffc3:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145ffc3:9000::/24ffc3:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146ffc3:9100::/24ffc3:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147ffc3:9200::/24ffc3:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148ffc3:9300::/24ffc3:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149ffc3:9400::/24ffc3:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150ffc3:9500::/24ffc3:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151ffc3:9600::/24ffc3:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152ffc3:9700::/24ffc3:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153ffc3:9800::/24ffc3:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154ffc3:9900::/24ffc3:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155ffc3:9a00::/24ffc3:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156ffc3:9b00::/24ffc3:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157ffc3:9c00::/24ffc3:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158ffc3:9d00::/24ffc3:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159ffc3:9e00::/24ffc3:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160ffc3:9f00::/24ffc3:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161ffc3:a000::/24ffc3:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162ffc3:a100::/24ffc3:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163ffc3:a200::/24ffc3:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164ffc3:a300::/24ffc3:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165ffc3:a400::/24ffc3:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166ffc3:a500::/24ffc3:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167ffc3:a600::/24ffc3:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168ffc3:a700::/24ffc3:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169ffc3:a800::/24ffc3:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170ffc3:a900::/24ffc3:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171ffc3:aa00::/24ffc3:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172ffc3:ab00::/24ffc3:abff:ffff:ffff:ffff:ffff:ffff:ffff
173ffc3:ac00::/24ffc3:acff:ffff:ffff:ffff:ffff:ffff:ffff
174ffc3:ad00::/24ffc3:adff:ffff:ffff:ffff:ffff:ffff:ffff
175ffc3:ae00::/24ffc3:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176ffc3:af00::/24ffc3:afff:ffff:ffff:ffff:ffff:ffff:ffff
177ffc3:b000::/24ffc3:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178ffc3:b100::/24ffc3:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179ffc3:b200::/24ffc3:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180ffc3:b300::/24ffc3:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181ffc3:b400::/24ffc3:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182ffc3:b500::/24ffc3:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183ffc3:b600::/24ffc3:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184ffc3:b700::/24ffc3:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185ffc3:b800::/24ffc3:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186ffc3:b900::/24ffc3:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187ffc3:ba00::/24ffc3:baff:ffff:ffff:ffff:ffff:ffff:ffff
188ffc3:bb00::/24ffc3:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189ffc3:bc00::/24ffc3:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190ffc3:bd00::/24ffc3:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191ffc3:be00::/24ffc3:beff:ffff:ffff:ffff:ffff:ffff:ffff
192ffc3:bf00::/24ffc3:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193ffc3:c000::/24ffc3:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194ffc3:c100::/24ffc3:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195ffc3:c200::/24ffc3:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196ffc3:c300::/24ffc3:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197ffc3:c400::/24ffc3:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198ffc3:c500::/24ffc3:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199ffc3:c600::/24ffc3:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200ffc3:c700::/24ffc3:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201ffc3:c800::/24ffc3:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202ffc3:c900::/24ffc3:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203ffc3:ca00::/24ffc3:caff:ffff:ffff:ffff:ffff:ffff:ffff
204ffc3:cb00::/24ffc3:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205ffc3:cc00::/24ffc3:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206ffc3:cd00::/24ffc3:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207ffc3:ce00::/24ffc3:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208ffc3:cf00::/24ffc3:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209ffc3:d000::/24ffc3:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210ffc3:d100::/24ffc3:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211ffc3:d200::/24ffc3:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212ffc3:d300::/24ffc3:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213ffc3:d400::/24ffc3:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214ffc3:d500::/24ffc3:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215ffc3:d600::/24ffc3:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216ffc3:d700::/24ffc3:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217ffc3:d800::/24ffc3:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218ffc3:d900::/24ffc3:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219ffc3:da00::/24ffc3:daff:ffff:ffff:ffff:ffff:ffff:ffff
220ffc3:db00::/24ffc3:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221ffc3:dc00::/24ffc3:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222ffc3:dd00::/24ffc3:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223ffc3:de00::/24ffc3:deff:ffff:ffff:ffff:ffff:ffff:ffff
224ffc3:df00::/24ffc3:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225ffc3:e000::/24ffc3:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226ffc3:e100::/24ffc3:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227ffc3:e200::/24ffc3:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228ffc3:e300::/24ffc3:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229ffc3:e400::/24ffc3:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230ffc3:e500::/24ffc3:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231ffc3:e600::/24ffc3:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232ffc3:e700::/24ffc3:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233ffc3:e800::/24ffc3:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234ffc3:e900::/24ffc3:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235ffc3:ea00::/24ffc3:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236ffc3:eb00::/24ffc3:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237ffc3:ec00::/24ffc3:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238ffc3:ed00::/24ffc3:edff:ffff:ffff:ffff:ffff:ffff:ffff
239ffc3:ee00::/24ffc3:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240ffc3:ef00::/24ffc3:efff:ffff:ffff:ffff:ffff:ffff:ffff
241ffc3:f000::/24ffc3:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242ffc3:f100::/24ffc3:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243ffc3:f200::/24ffc3:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244ffc3:f300::/24ffc3:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245ffc3:f400::/24ffc3:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246ffc3:f500::/24ffc3:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247ffc3:f600::/24ffc3:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248ffc3:f700::/24ffc3:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249ffc3:f800::/24ffc3:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250ffc3:f900::/24ffc3:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251ffc3:fa00::/24ffc3:faff:ffff:ffff:ffff:ffff:ffff:ffff
252ffc3:fb00::/24ffc3:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253ffc3:fc00::/24ffc3:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254ffc3:fd00::/24ffc3:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255ffc3:fe00::/24ffc3:feff:ffff:ffff:ffff:ffff:ffff:ffff
256ffc3:ff00::/24ffc3:ffff:ffff:ffff:ffff:ffff:ffff: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

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.