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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
ff6f::/16
First address
ff6f::
Last address
ff6f: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
ff6f:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
f.6.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)

ff6f::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1ff6f::/24ff6f:ff:ffff:ffff:ffff:ffff:ffff:ffff
2ff6f:100::/24ff6f:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3ff6f:200::/24ff6f:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4ff6f:300::/24ff6f:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5ff6f:400::/24ff6f:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6ff6f:500::/24ff6f:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7ff6f:600::/24ff6f:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8ff6f:700::/24ff6f:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9ff6f:800::/24ff6f:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10ff6f:900::/24ff6f:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11ff6f:a00::/24ff6f:aff:ffff:ffff:ffff:ffff:ffff:ffff
12ff6f:b00::/24ff6f:bff:ffff:ffff:ffff:ffff:ffff:ffff
13ff6f:c00::/24ff6f:cff:ffff:ffff:ffff:ffff:ffff:ffff
14ff6f:d00::/24ff6f:dff:ffff:ffff:ffff:ffff:ffff:ffff
15ff6f:e00::/24ff6f:eff:ffff:ffff:ffff:ffff:ffff:ffff
16ff6f:f00::/24ff6f:fff:ffff:ffff:ffff:ffff:ffff:ffff
17ff6f:1000::/24ff6f:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18ff6f:1100::/24ff6f:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19ff6f:1200::/24ff6f:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20ff6f:1300::/24ff6f:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21ff6f:1400::/24ff6f:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22ff6f:1500::/24ff6f:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23ff6f:1600::/24ff6f:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24ff6f:1700::/24ff6f:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25ff6f:1800::/24ff6f:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26ff6f:1900::/24ff6f:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27ff6f:1a00::/24ff6f:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28ff6f:1b00::/24ff6f:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29ff6f:1c00::/24ff6f:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30ff6f:1d00::/24ff6f:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31ff6f:1e00::/24ff6f:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32ff6f:1f00::/24ff6f:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33ff6f:2000::/24ff6f:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34ff6f:2100::/24ff6f:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35ff6f:2200::/24ff6f:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36ff6f:2300::/24ff6f:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37ff6f:2400::/24ff6f:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38ff6f:2500::/24ff6f:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39ff6f:2600::/24ff6f:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40ff6f:2700::/24ff6f:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41ff6f:2800::/24ff6f:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42ff6f:2900::/24ff6f:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43ff6f:2a00::/24ff6f:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44ff6f:2b00::/24ff6f:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45ff6f:2c00::/24ff6f:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46ff6f:2d00::/24ff6f:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47ff6f:2e00::/24ff6f:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48ff6f:2f00::/24ff6f:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49ff6f:3000::/24ff6f:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50ff6f:3100::/24ff6f:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51ff6f:3200::/24ff6f:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52ff6f:3300::/24ff6f:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53ff6f:3400::/24ff6f:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54ff6f:3500::/24ff6f:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55ff6f:3600::/24ff6f:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56ff6f:3700::/24ff6f:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57ff6f:3800::/24ff6f:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58ff6f:3900::/24ff6f:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59ff6f:3a00::/24ff6f:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60ff6f:3b00::/24ff6f:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61ff6f:3c00::/24ff6f:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62ff6f:3d00::/24ff6f:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63ff6f:3e00::/24ff6f:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64ff6f:3f00::/24ff6f:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65ff6f:4000::/24ff6f:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66ff6f:4100::/24ff6f:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67ff6f:4200::/24ff6f:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68ff6f:4300::/24ff6f:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69ff6f:4400::/24ff6f:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70ff6f:4500::/24ff6f:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71ff6f:4600::/24ff6f:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72ff6f:4700::/24ff6f:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73ff6f:4800::/24ff6f:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74ff6f:4900::/24ff6f:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75ff6f:4a00::/24ff6f:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76ff6f:4b00::/24ff6f:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77ff6f:4c00::/24ff6f:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78ff6f:4d00::/24ff6f:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79ff6f:4e00::/24ff6f:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80ff6f:4f00::/24ff6f:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81ff6f:5000::/24ff6f:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82ff6f:5100::/24ff6f:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83ff6f:5200::/24ff6f:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84ff6f:5300::/24ff6f:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85ff6f:5400::/24ff6f:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86ff6f:5500::/24ff6f:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87ff6f:5600::/24ff6f:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88ff6f:5700::/24ff6f:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89ff6f:5800::/24ff6f:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90ff6f:5900::/24ff6f:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91ff6f:5a00::/24ff6f:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92ff6f:5b00::/24ff6f:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93ff6f:5c00::/24ff6f:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94ff6f:5d00::/24ff6f:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95ff6f:5e00::/24ff6f:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96ff6f:5f00::/24ff6f:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97ff6f:6000::/24ff6f:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98ff6f:6100::/24ff6f:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99ff6f:6200::/24ff6f:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100ff6f:6300::/24ff6f:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101ff6f:6400::/24ff6f:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102ff6f:6500::/24ff6f:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103ff6f:6600::/24ff6f:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104ff6f:6700::/24ff6f:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105ff6f:6800::/24ff6f:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106ff6f:6900::/24ff6f:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107ff6f:6a00::/24ff6f:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108ff6f:6b00::/24ff6f:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109ff6f:6c00::/24ff6f:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110ff6f:6d00::/24ff6f:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111ff6f:6e00::/24ff6f:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112ff6f:6f00::/24ff6f:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113ff6f:7000::/24ff6f:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114ff6f:7100::/24ff6f:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115ff6f:7200::/24ff6f:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116ff6f:7300::/24ff6f:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117ff6f:7400::/24ff6f:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118ff6f:7500::/24ff6f:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119ff6f:7600::/24ff6f:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120ff6f:7700::/24ff6f:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121ff6f:7800::/24ff6f:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122ff6f:7900::/24ff6f:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123ff6f:7a00::/24ff6f:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124ff6f:7b00::/24ff6f:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125ff6f:7c00::/24ff6f:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126ff6f:7d00::/24ff6f:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127ff6f:7e00::/24ff6f:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128ff6f:7f00::/24ff6f:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129ff6f:8000::/24ff6f:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130ff6f:8100::/24ff6f:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131ff6f:8200::/24ff6f:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132ff6f:8300::/24ff6f:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133ff6f:8400::/24ff6f:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134ff6f:8500::/24ff6f:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135ff6f:8600::/24ff6f:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136ff6f:8700::/24ff6f:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137ff6f:8800::/24ff6f:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138ff6f:8900::/24ff6f:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139ff6f:8a00::/24ff6f:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140ff6f:8b00::/24ff6f:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141ff6f:8c00::/24ff6f:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142ff6f:8d00::/24ff6f:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143ff6f:8e00::/24ff6f:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144ff6f:8f00::/24ff6f:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145ff6f:9000::/24ff6f:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146ff6f:9100::/24ff6f:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147ff6f:9200::/24ff6f:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148ff6f:9300::/24ff6f:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149ff6f:9400::/24ff6f:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150ff6f:9500::/24ff6f:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151ff6f:9600::/24ff6f:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152ff6f:9700::/24ff6f:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153ff6f:9800::/24ff6f:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154ff6f:9900::/24ff6f:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155ff6f:9a00::/24ff6f:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156ff6f:9b00::/24ff6f:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157ff6f:9c00::/24ff6f:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158ff6f:9d00::/24ff6f:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159ff6f:9e00::/24ff6f:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160ff6f:9f00::/24ff6f:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161ff6f:a000::/24ff6f:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162ff6f:a100::/24ff6f:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163ff6f:a200::/24ff6f:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164ff6f:a300::/24ff6f:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165ff6f:a400::/24ff6f:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166ff6f:a500::/24ff6f:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167ff6f:a600::/24ff6f:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168ff6f:a700::/24ff6f:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169ff6f:a800::/24ff6f:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170ff6f:a900::/24ff6f:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171ff6f:aa00::/24ff6f:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172ff6f:ab00::/24ff6f:abff:ffff:ffff:ffff:ffff:ffff:ffff
173ff6f:ac00::/24ff6f:acff:ffff:ffff:ffff:ffff:ffff:ffff
174ff6f:ad00::/24ff6f:adff:ffff:ffff:ffff:ffff:ffff:ffff
175ff6f:ae00::/24ff6f:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176ff6f:af00::/24ff6f:afff:ffff:ffff:ffff:ffff:ffff:ffff
177ff6f:b000::/24ff6f:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178ff6f:b100::/24ff6f:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179ff6f:b200::/24ff6f:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180ff6f:b300::/24ff6f:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181ff6f:b400::/24ff6f:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182ff6f:b500::/24ff6f:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183ff6f:b600::/24ff6f:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184ff6f:b700::/24ff6f:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185ff6f:b800::/24ff6f:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186ff6f:b900::/24ff6f:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187ff6f:ba00::/24ff6f:baff:ffff:ffff:ffff:ffff:ffff:ffff
188ff6f:bb00::/24ff6f:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189ff6f:bc00::/24ff6f:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190ff6f:bd00::/24ff6f:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191ff6f:be00::/24ff6f:beff:ffff:ffff:ffff:ffff:ffff:ffff
192ff6f:bf00::/24ff6f:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193ff6f:c000::/24ff6f:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194ff6f:c100::/24ff6f:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195ff6f:c200::/24ff6f:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196ff6f:c300::/24ff6f:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197ff6f:c400::/24ff6f:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198ff6f:c500::/24ff6f:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199ff6f:c600::/24ff6f:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200ff6f:c700::/24ff6f:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201ff6f:c800::/24ff6f:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202ff6f:c900::/24ff6f:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203ff6f:ca00::/24ff6f:caff:ffff:ffff:ffff:ffff:ffff:ffff
204ff6f:cb00::/24ff6f:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205ff6f:cc00::/24ff6f:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206ff6f:cd00::/24ff6f:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207ff6f:ce00::/24ff6f:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208ff6f:cf00::/24ff6f:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209ff6f:d000::/24ff6f:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210ff6f:d100::/24ff6f:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211ff6f:d200::/24ff6f:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212ff6f:d300::/24ff6f:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213ff6f:d400::/24ff6f:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214ff6f:d500::/24ff6f:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215ff6f:d600::/24ff6f:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216ff6f:d700::/24ff6f:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217ff6f:d800::/24ff6f:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218ff6f:d900::/24ff6f:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219ff6f:da00::/24ff6f:daff:ffff:ffff:ffff:ffff:ffff:ffff
220ff6f:db00::/24ff6f:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221ff6f:dc00::/24ff6f:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222ff6f:dd00::/24ff6f:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223ff6f:de00::/24ff6f:deff:ffff:ffff:ffff:ffff:ffff:ffff
224ff6f:df00::/24ff6f:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225ff6f:e000::/24ff6f:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226ff6f:e100::/24ff6f:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227ff6f:e200::/24ff6f:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228ff6f:e300::/24ff6f:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229ff6f:e400::/24ff6f:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230ff6f:e500::/24ff6f:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231ff6f:e600::/24ff6f:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232ff6f:e700::/24ff6f:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233ff6f:e800::/24ff6f:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234ff6f:e900::/24ff6f:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235ff6f:ea00::/24ff6f:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236ff6f:eb00::/24ff6f:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237ff6f:ec00::/24ff6f:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238ff6f:ed00::/24ff6f:edff:ffff:ffff:ffff:ffff:ffff:ffff
239ff6f:ee00::/24ff6f:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240ff6f:ef00::/24ff6f:efff:ffff:ffff:ffff:ffff:ffff:ffff
241ff6f:f000::/24ff6f:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242ff6f:f100::/24ff6f:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243ff6f:f200::/24ff6f:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244ff6f:f300::/24ff6f:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245ff6f:f400::/24ff6f:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246ff6f:f500::/24ff6f:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247ff6f:f600::/24ff6f:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248ff6f:f700::/24ff6f:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249ff6f:f800::/24ff6f:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250ff6f:f900::/24ff6f:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251ff6f:fa00::/24ff6f:faff:ffff:ffff:ffff:ffff:ffff:ffff
252ff6f:fb00::/24ff6f:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253ff6f:fc00::/24ff6f:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254ff6f:fd00::/24ff6f:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255ff6f:fe00::/24ff6f:feff:ffff:ffff:ffff:ffff:ffff:ffff
256ff6f:ff00::/24ff6f: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.