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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
fccb::/16
First address
fccb::
Last address
fccb: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
fccb:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
b.c.c.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

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

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