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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/20
Addresses2^108
/64 networks2^44
Network
ff0b:2000::/20
First address
ff0b:2000::
Last address
ff0b:2fff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
324,518,553,658,426,726,783,156,020,576,256 (2^108)
/64 networks (LANs)
17,592,186,044,416 (2^44)
Full form
ff0b:2000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
2.b.0.f.f.ip6.arpa
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

ff0b:2000::/20 makes 256 subnets of /28.

Subnets
#SubnetLast address
1ff0b:2000::/28ff0b:200f:ffff:ffff:ffff:ffff:ffff:ffff
2ff0b:2010::/28ff0b:201f:ffff:ffff:ffff:ffff:ffff:ffff
3ff0b:2020::/28ff0b:202f:ffff:ffff:ffff:ffff:ffff:ffff
4ff0b:2030::/28ff0b:203f:ffff:ffff:ffff:ffff:ffff:ffff
5ff0b:2040::/28ff0b:204f:ffff:ffff:ffff:ffff:ffff:ffff
6ff0b:2050::/28ff0b:205f:ffff:ffff:ffff:ffff:ffff:ffff
7ff0b:2060::/28ff0b:206f:ffff:ffff:ffff:ffff:ffff:ffff
8ff0b:2070::/28ff0b:207f:ffff:ffff:ffff:ffff:ffff:ffff
9ff0b:2080::/28ff0b:208f:ffff:ffff:ffff:ffff:ffff:ffff
10ff0b:2090::/28ff0b:209f:ffff:ffff:ffff:ffff:ffff:ffff
11ff0b:20a0::/28ff0b:20af:ffff:ffff:ffff:ffff:ffff:ffff
12ff0b:20b0::/28ff0b:20bf:ffff:ffff:ffff:ffff:ffff:ffff
13ff0b:20c0::/28ff0b:20cf:ffff:ffff:ffff:ffff:ffff:ffff
14ff0b:20d0::/28ff0b:20df:ffff:ffff:ffff:ffff:ffff:ffff
15ff0b:20e0::/28ff0b:20ef:ffff:ffff:ffff:ffff:ffff:ffff
16ff0b:20f0::/28ff0b:20ff:ffff:ffff:ffff:ffff:ffff:ffff
17ff0b:2100::/28ff0b:210f:ffff:ffff:ffff:ffff:ffff:ffff
18ff0b:2110::/28ff0b:211f:ffff:ffff:ffff:ffff:ffff:ffff
19ff0b:2120::/28ff0b:212f:ffff:ffff:ffff:ffff:ffff:ffff
20ff0b:2130::/28ff0b:213f:ffff:ffff:ffff:ffff:ffff:ffff
21ff0b:2140::/28ff0b:214f:ffff:ffff:ffff:ffff:ffff:ffff
22ff0b:2150::/28ff0b:215f:ffff:ffff:ffff:ffff:ffff:ffff
23ff0b:2160::/28ff0b:216f:ffff:ffff:ffff:ffff:ffff:ffff
24ff0b:2170::/28ff0b:217f:ffff:ffff:ffff:ffff:ffff:ffff
25ff0b:2180::/28ff0b:218f:ffff:ffff:ffff:ffff:ffff:ffff
26ff0b:2190::/28ff0b:219f:ffff:ffff:ffff:ffff:ffff:ffff
27ff0b:21a0::/28ff0b:21af:ffff:ffff:ffff:ffff:ffff:ffff
28ff0b:21b0::/28ff0b:21bf:ffff:ffff:ffff:ffff:ffff:ffff
29ff0b:21c0::/28ff0b:21cf:ffff:ffff:ffff:ffff:ffff:ffff
30ff0b:21d0::/28ff0b:21df:ffff:ffff:ffff:ffff:ffff:ffff
31ff0b:21e0::/28ff0b:21ef:ffff:ffff:ffff:ffff:ffff:ffff
32ff0b:21f0::/28ff0b:21ff:ffff:ffff:ffff:ffff:ffff:ffff
33ff0b:2200::/28ff0b:220f:ffff:ffff:ffff:ffff:ffff:ffff
34ff0b:2210::/28ff0b:221f:ffff:ffff:ffff:ffff:ffff:ffff
35ff0b:2220::/28ff0b:222f:ffff:ffff:ffff:ffff:ffff:ffff
36ff0b:2230::/28ff0b:223f:ffff:ffff:ffff:ffff:ffff:ffff
37ff0b:2240::/28ff0b:224f:ffff:ffff:ffff:ffff:ffff:ffff
38ff0b:2250::/28ff0b:225f:ffff:ffff:ffff:ffff:ffff:ffff
39ff0b:2260::/28ff0b:226f:ffff:ffff:ffff:ffff:ffff:ffff
40ff0b:2270::/28ff0b:227f:ffff:ffff:ffff:ffff:ffff:ffff
41ff0b:2280::/28ff0b:228f:ffff:ffff:ffff:ffff:ffff:ffff
42ff0b:2290::/28ff0b:229f:ffff:ffff:ffff:ffff:ffff:ffff
43ff0b:22a0::/28ff0b:22af:ffff:ffff:ffff:ffff:ffff:ffff
44ff0b:22b0::/28ff0b:22bf:ffff:ffff:ffff:ffff:ffff:ffff
45ff0b:22c0::/28ff0b:22cf:ffff:ffff:ffff:ffff:ffff:ffff
46ff0b:22d0::/28ff0b:22df:ffff:ffff:ffff:ffff:ffff:ffff
47ff0b:22e0::/28ff0b:22ef:ffff:ffff:ffff:ffff:ffff:ffff
48ff0b:22f0::/28ff0b:22ff:ffff:ffff:ffff:ffff:ffff:ffff
49ff0b:2300::/28ff0b:230f:ffff:ffff:ffff:ffff:ffff:ffff
50ff0b:2310::/28ff0b:231f:ffff:ffff:ffff:ffff:ffff:ffff
51ff0b:2320::/28ff0b:232f:ffff:ffff:ffff:ffff:ffff:ffff
52ff0b:2330::/28ff0b:233f:ffff:ffff:ffff:ffff:ffff:ffff
53ff0b:2340::/28ff0b:234f:ffff:ffff:ffff:ffff:ffff:ffff
54ff0b:2350::/28ff0b:235f:ffff:ffff:ffff:ffff:ffff:ffff
55ff0b:2360::/28ff0b:236f:ffff:ffff:ffff:ffff:ffff:ffff
56ff0b:2370::/28ff0b:237f:ffff:ffff:ffff:ffff:ffff:ffff
57ff0b:2380::/28ff0b:238f:ffff:ffff:ffff:ffff:ffff:ffff
58ff0b:2390::/28ff0b:239f:ffff:ffff:ffff:ffff:ffff:ffff
59ff0b:23a0::/28ff0b:23af:ffff:ffff:ffff:ffff:ffff:ffff
60ff0b:23b0::/28ff0b:23bf:ffff:ffff:ffff:ffff:ffff:ffff
61ff0b:23c0::/28ff0b:23cf:ffff:ffff:ffff:ffff:ffff:ffff
62ff0b:23d0::/28ff0b:23df:ffff:ffff:ffff:ffff:ffff:ffff
63ff0b:23e0::/28ff0b:23ef:ffff:ffff:ffff:ffff:ffff:ffff
64ff0b:23f0::/28ff0b:23ff:ffff:ffff:ffff:ffff:ffff:ffff
65ff0b:2400::/28ff0b:240f:ffff:ffff:ffff:ffff:ffff:ffff
66ff0b:2410::/28ff0b:241f:ffff:ffff:ffff:ffff:ffff:ffff
67ff0b:2420::/28ff0b:242f:ffff:ffff:ffff:ffff:ffff:ffff
68ff0b:2430::/28ff0b:243f:ffff:ffff:ffff:ffff:ffff:ffff
69ff0b:2440::/28ff0b:244f:ffff:ffff:ffff:ffff:ffff:ffff
70ff0b:2450::/28ff0b:245f:ffff:ffff:ffff:ffff:ffff:ffff
71ff0b:2460::/28ff0b:246f:ffff:ffff:ffff:ffff:ffff:ffff
72ff0b:2470::/28ff0b:247f:ffff:ffff:ffff:ffff:ffff:ffff
73ff0b:2480::/28ff0b:248f:ffff:ffff:ffff:ffff:ffff:ffff
74ff0b:2490::/28ff0b:249f:ffff:ffff:ffff:ffff:ffff:ffff
75ff0b:24a0::/28ff0b:24af:ffff:ffff:ffff:ffff:ffff:ffff
76ff0b:24b0::/28ff0b:24bf:ffff:ffff:ffff:ffff:ffff:ffff
77ff0b:24c0::/28ff0b:24cf:ffff:ffff:ffff:ffff:ffff:ffff
78ff0b:24d0::/28ff0b:24df:ffff:ffff:ffff:ffff:ffff:ffff
79ff0b:24e0::/28ff0b:24ef:ffff:ffff:ffff:ffff:ffff:ffff
80ff0b:24f0::/28ff0b:24ff:ffff:ffff:ffff:ffff:ffff:ffff
81ff0b:2500::/28ff0b:250f:ffff:ffff:ffff:ffff:ffff:ffff
82ff0b:2510::/28ff0b:251f:ffff:ffff:ffff:ffff:ffff:ffff
83ff0b:2520::/28ff0b:252f:ffff:ffff:ffff:ffff:ffff:ffff
84ff0b:2530::/28ff0b:253f:ffff:ffff:ffff:ffff:ffff:ffff
85ff0b:2540::/28ff0b:254f:ffff:ffff:ffff:ffff:ffff:ffff
86ff0b:2550::/28ff0b:255f:ffff:ffff:ffff:ffff:ffff:ffff
87ff0b:2560::/28ff0b:256f:ffff:ffff:ffff:ffff:ffff:ffff
88ff0b:2570::/28ff0b:257f:ffff:ffff:ffff:ffff:ffff:ffff
89ff0b:2580::/28ff0b:258f:ffff:ffff:ffff:ffff:ffff:ffff
90ff0b:2590::/28ff0b:259f:ffff:ffff:ffff:ffff:ffff:ffff
91ff0b:25a0::/28ff0b:25af:ffff:ffff:ffff:ffff:ffff:ffff
92ff0b:25b0::/28ff0b:25bf:ffff:ffff:ffff:ffff:ffff:ffff
93ff0b:25c0::/28ff0b:25cf:ffff:ffff:ffff:ffff:ffff:ffff
94ff0b:25d0::/28ff0b:25df:ffff:ffff:ffff:ffff:ffff:ffff
95ff0b:25e0::/28ff0b:25ef:ffff:ffff:ffff:ffff:ffff:ffff
96ff0b:25f0::/28ff0b:25ff:ffff:ffff:ffff:ffff:ffff:ffff
97ff0b:2600::/28ff0b:260f:ffff:ffff:ffff:ffff:ffff:ffff
98ff0b:2610::/28ff0b:261f:ffff:ffff:ffff:ffff:ffff:ffff
99ff0b:2620::/28ff0b:262f:ffff:ffff:ffff:ffff:ffff:ffff
100ff0b:2630::/28ff0b:263f:ffff:ffff:ffff:ffff:ffff:ffff
101ff0b:2640::/28ff0b:264f:ffff:ffff:ffff:ffff:ffff:ffff
102ff0b:2650::/28ff0b:265f:ffff:ffff:ffff:ffff:ffff:ffff
103ff0b:2660::/28ff0b:266f:ffff:ffff:ffff:ffff:ffff:ffff
104ff0b:2670::/28ff0b:267f:ffff:ffff:ffff:ffff:ffff:ffff
105ff0b:2680::/28ff0b:268f:ffff:ffff:ffff:ffff:ffff:ffff
106ff0b:2690::/28ff0b:269f:ffff:ffff:ffff:ffff:ffff:ffff
107ff0b:26a0::/28ff0b:26af:ffff:ffff:ffff:ffff:ffff:ffff
108ff0b:26b0::/28ff0b:26bf:ffff:ffff:ffff:ffff:ffff:ffff
109ff0b:26c0::/28ff0b:26cf:ffff:ffff:ffff:ffff:ffff:ffff
110ff0b:26d0::/28ff0b:26df:ffff:ffff:ffff:ffff:ffff:ffff
111ff0b:26e0::/28ff0b:26ef:ffff:ffff:ffff:ffff:ffff:ffff
112ff0b:26f0::/28ff0b:26ff:ffff:ffff:ffff:ffff:ffff:ffff
113ff0b:2700::/28ff0b:270f:ffff:ffff:ffff:ffff:ffff:ffff
114ff0b:2710::/28ff0b:271f:ffff:ffff:ffff:ffff:ffff:ffff
115ff0b:2720::/28ff0b:272f:ffff:ffff:ffff:ffff:ffff:ffff
116ff0b:2730::/28ff0b:273f:ffff:ffff:ffff:ffff:ffff:ffff
117ff0b:2740::/28ff0b:274f:ffff:ffff:ffff:ffff:ffff:ffff
118ff0b:2750::/28ff0b:275f:ffff:ffff:ffff:ffff:ffff:ffff
119ff0b:2760::/28ff0b:276f:ffff:ffff:ffff:ffff:ffff:ffff
120ff0b:2770::/28ff0b:277f:ffff:ffff:ffff:ffff:ffff:ffff
121ff0b:2780::/28ff0b:278f:ffff:ffff:ffff:ffff:ffff:ffff
122ff0b:2790::/28ff0b:279f:ffff:ffff:ffff:ffff:ffff:ffff
123ff0b:27a0::/28ff0b:27af:ffff:ffff:ffff:ffff:ffff:ffff
124ff0b:27b0::/28ff0b:27bf:ffff:ffff:ffff:ffff:ffff:ffff
125ff0b:27c0::/28ff0b:27cf:ffff:ffff:ffff:ffff:ffff:ffff
126ff0b:27d0::/28ff0b:27df:ffff:ffff:ffff:ffff:ffff:ffff
127ff0b:27e0::/28ff0b:27ef:ffff:ffff:ffff:ffff:ffff:ffff
128ff0b:27f0::/28ff0b:27ff:ffff:ffff:ffff:ffff:ffff:ffff
129ff0b:2800::/28ff0b:280f:ffff:ffff:ffff:ffff:ffff:ffff
130ff0b:2810::/28ff0b:281f:ffff:ffff:ffff:ffff:ffff:ffff
131ff0b:2820::/28ff0b:282f:ffff:ffff:ffff:ffff:ffff:ffff
132ff0b:2830::/28ff0b:283f:ffff:ffff:ffff:ffff:ffff:ffff
133ff0b:2840::/28ff0b:284f:ffff:ffff:ffff:ffff:ffff:ffff
134ff0b:2850::/28ff0b:285f:ffff:ffff:ffff:ffff:ffff:ffff
135ff0b:2860::/28ff0b:286f:ffff:ffff:ffff:ffff:ffff:ffff
136ff0b:2870::/28ff0b:287f:ffff:ffff:ffff:ffff:ffff:ffff
137ff0b:2880::/28ff0b:288f:ffff:ffff:ffff:ffff:ffff:ffff
138ff0b:2890::/28ff0b:289f:ffff:ffff:ffff:ffff:ffff:ffff
139ff0b:28a0::/28ff0b:28af:ffff:ffff:ffff:ffff:ffff:ffff
140ff0b:28b0::/28ff0b:28bf:ffff:ffff:ffff:ffff:ffff:ffff
141ff0b:28c0::/28ff0b:28cf:ffff:ffff:ffff:ffff:ffff:ffff
142ff0b:28d0::/28ff0b:28df:ffff:ffff:ffff:ffff:ffff:ffff
143ff0b:28e0::/28ff0b:28ef:ffff:ffff:ffff:ffff:ffff:ffff
144ff0b:28f0::/28ff0b:28ff:ffff:ffff:ffff:ffff:ffff:ffff
145ff0b:2900::/28ff0b:290f:ffff:ffff:ffff:ffff:ffff:ffff
146ff0b:2910::/28ff0b:291f:ffff:ffff:ffff:ffff:ffff:ffff
147ff0b:2920::/28ff0b:292f:ffff:ffff:ffff:ffff:ffff:ffff
148ff0b:2930::/28ff0b:293f:ffff:ffff:ffff:ffff:ffff:ffff
149ff0b:2940::/28ff0b:294f:ffff:ffff:ffff:ffff:ffff:ffff
150ff0b:2950::/28ff0b:295f:ffff:ffff:ffff:ffff:ffff:ffff
151ff0b:2960::/28ff0b:296f:ffff:ffff:ffff:ffff:ffff:ffff
152ff0b:2970::/28ff0b:297f:ffff:ffff:ffff:ffff:ffff:ffff
153ff0b:2980::/28ff0b:298f:ffff:ffff:ffff:ffff:ffff:ffff
154ff0b:2990::/28ff0b:299f:ffff:ffff:ffff:ffff:ffff:ffff
155ff0b:29a0::/28ff0b:29af:ffff:ffff:ffff:ffff:ffff:ffff
156ff0b:29b0::/28ff0b:29bf:ffff:ffff:ffff:ffff:ffff:ffff
157ff0b:29c0::/28ff0b:29cf:ffff:ffff:ffff:ffff:ffff:ffff
158ff0b:29d0::/28ff0b:29df:ffff:ffff:ffff:ffff:ffff:ffff
159ff0b:29e0::/28ff0b:29ef:ffff:ffff:ffff:ffff:ffff:ffff
160ff0b:29f0::/28ff0b:29ff:ffff:ffff:ffff:ffff:ffff:ffff
161ff0b:2a00::/28ff0b:2a0f:ffff:ffff:ffff:ffff:ffff:ffff
162ff0b:2a10::/28ff0b:2a1f:ffff:ffff:ffff:ffff:ffff:ffff
163ff0b:2a20::/28ff0b:2a2f:ffff:ffff:ffff:ffff:ffff:ffff
164ff0b:2a30::/28ff0b:2a3f:ffff:ffff:ffff:ffff:ffff:ffff
165ff0b:2a40::/28ff0b:2a4f:ffff:ffff:ffff:ffff:ffff:ffff
166ff0b:2a50::/28ff0b:2a5f:ffff:ffff:ffff:ffff:ffff:ffff
167ff0b:2a60::/28ff0b:2a6f:ffff:ffff:ffff:ffff:ffff:ffff
168ff0b:2a70::/28ff0b:2a7f:ffff:ffff:ffff:ffff:ffff:ffff
169ff0b:2a80::/28ff0b:2a8f:ffff:ffff:ffff:ffff:ffff:ffff
170ff0b:2a90::/28ff0b:2a9f:ffff:ffff:ffff:ffff:ffff:ffff
171ff0b:2aa0::/28ff0b:2aaf:ffff:ffff:ffff:ffff:ffff:ffff
172ff0b:2ab0::/28ff0b:2abf:ffff:ffff:ffff:ffff:ffff:ffff
173ff0b:2ac0::/28ff0b:2acf:ffff:ffff:ffff:ffff:ffff:ffff
174ff0b:2ad0::/28ff0b:2adf:ffff:ffff:ffff:ffff:ffff:ffff
175ff0b:2ae0::/28ff0b:2aef:ffff:ffff:ffff:ffff:ffff:ffff
176ff0b:2af0::/28ff0b:2aff:ffff:ffff:ffff:ffff:ffff:ffff
177ff0b:2b00::/28ff0b:2b0f:ffff:ffff:ffff:ffff:ffff:ffff
178ff0b:2b10::/28ff0b:2b1f:ffff:ffff:ffff:ffff:ffff:ffff
179ff0b:2b20::/28ff0b:2b2f:ffff:ffff:ffff:ffff:ffff:ffff
180ff0b:2b30::/28ff0b:2b3f:ffff:ffff:ffff:ffff:ffff:ffff
181ff0b:2b40::/28ff0b:2b4f:ffff:ffff:ffff:ffff:ffff:ffff
182ff0b:2b50::/28ff0b:2b5f:ffff:ffff:ffff:ffff:ffff:ffff
183ff0b:2b60::/28ff0b:2b6f:ffff:ffff:ffff:ffff:ffff:ffff
184ff0b:2b70::/28ff0b:2b7f:ffff:ffff:ffff:ffff:ffff:ffff
185ff0b:2b80::/28ff0b:2b8f:ffff:ffff:ffff:ffff:ffff:ffff
186ff0b:2b90::/28ff0b:2b9f:ffff:ffff:ffff:ffff:ffff:ffff
187ff0b:2ba0::/28ff0b:2baf:ffff:ffff:ffff:ffff:ffff:ffff
188ff0b:2bb0::/28ff0b:2bbf:ffff:ffff:ffff:ffff:ffff:ffff
189ff0b:2bc0::/28ff0b:2bcf:ffff:ffff:ffff:ffff:ffff:ffff
190ff0b:2bd0::/28ff0b:2bdf:ffff:ffff:ffff:ffff:ffff:ffff
191ff0b:2be0::/28ff0b:2bef:ffff:ffff:ffff:ffff:ffff:ffff
192ff0b:2bf0::/28ff0b:2bff:ffff:ffff:ffff:ffff:ffff:ffff
193ff0b:2c00::/28ff0b:2c0f:ffff:ffff:ffff:ffff:ffff:ffff
194ff0b:2c10::/28ff0b:2c1f:ffff:ffff:ffff:ffff:ffff:ffff
195ff0b:2c20::/28ff0b:2c2f:ffff:ffff:ffff:ffff:ffff:ffff
196ff0b:2c30::/28ff0b:2c3f:ffff:ffff:ffff:ffff:ffff:ffff
197ff0b:2c40::/28ff0b:2c4f:ffff:ffff:ffff:ffff:ffff:ffff
198ff0b:2c50::/28ff0b:2c5f:ffff:ffff:ffff:ffff:ffff:ffff
199ff0b:2c60::/28ff0b:2c6f:ffff:ffff:ffff:ffff:ffff:ffff
200ff0b:2c70::/28ff0b:2c7f:ffff:ffff:ffff:ffff:ffff:ffff
201ff0b:2c80::/28ff0b:2c8f:ffff:ffff:ffff:ffff:ffff:ffff
202ff0b:2c90::/28ff0b:2c9f:ffff:ffff:ffff:ffff:ffff:ffff
203ff0b:2ca0::/28ff0b:2caf:ffff:ffff:ffff:ffff:ffff:ffff
204ff0b:2cb0::/28ff0b:2cbf:ffff:ffff:ffff:ffff:ffff:ffff
205ff0b:2cc0::/28ff0b:2ccf:ffff:ffff:ffff:ffff:ffff:ffff
206ff0b:2cd0::/28ff0b:2cdf:ffff:ffff:ffff:ffff:ffff:ffff
207ff0b:2ce0::/28ff0b:2cef:ffff:ffff:ffff:ffff:ffff:ffff
208ff0b:2cf0::/28ff0b:2cff:ffff:ffff:ffff:ffff:ffff:ffff
209ff0b:2d00::/28ff0b:2d0f:ffff:ffff:ffff:ffff:ffff:ffff
210ff0b:2d10::/28ff0b:2d1f:ffff:ffff:ffff:ffff:ffff:ffff
211ff0b:2d20::/28ff0b:2d2f:ffff:ffff:ffff:ffff:ffff:ffff
212ff0b:2d30::/28ff0b:2d3f:ffff:ffff:ffff:ffff:ffff:ffff
213ff0b:2d40::/28ff0b:2d4f:ffff:ffff:ffff:ffff:ffff:ffff
214ff0b:2d50::/28ff0b:2d5f:ffff:ffff:ffff:ffff:ffff:ffff
215ff0b:2d60::/28ff0b:2d6f:ffff:ffff:ffff:ffff:ffff:ffff
216ff0b:2d70::/28ff0b:2d7f:ffff:ffff:ffff:ffff:ffff:ffff
217ff0b:2d80::/28ff0b:2d8f:ffff:ffff:ffff:ffff:ffff:ffff
218ff0b:2d90::/28ff0b:2d9f:ffff:ffff:ffff:ffff:ffff:ffff
219ff0b:2da0::/28ff0b:2daf:ffff:ffff:ffff:ffff:ffff:ffff
220ff0b:2db0::/28ff0b:2dbf:ffff:ffff:ffff:ffff:ffff:ffff
221ff0b:2dc0::/28ff0b:2dcf:ffff:ffff:ffff:ffff:ffff:ffff
222ff0b:2dd0::/28ff0b:2ddf:ffff:ffff:ffff:ffff:ffff:ffff
223ff0b:2de0::/28ff0b:2def:ffff:ffff:ffff:ffff:ffff:ffff
224ff0b:2df0::/28ff0b:2dff:ffff:ffff:ffff:ffff:ffff:ffff
225ff0b:2e00::/28ff0b:2e0f:ffff:ffff:ffff:ffff:ffff:ffff
226ff0b:2e10::/28ff0b:2e1f:ffff:ffff:ffff:ffff:ffff:ffff
227ff0b:2e20::/28ff0b:2e2f:ffff:ffff:ffff:ffff:ffff:ffff
228ff0b:2e30::/28ff0b:2e3f:ffff:ffff:ffff:ffff:ffff:ffff
229ff0b:2e40::/28ff0b:2e4f:ffff:ffff:ffff:ffff:ffff:ffff
230ff0b:2e50::/28ff0b:2e5f:ffff:ffff:ffff:ffff:ffff:ffff
231ff0b:2e60::/28ff0b:2e6f:ffff:ffff:ffff:ffff:ffff:ffff
232ff0b:2e70::/28ff0b:2e7f:ffff:ffff:ffff:ffff:ffff:ffff
233ff0b:2e80::/28ff0b:2e8f:ffff:ffff:ffff:ffff:ffff:ffff
234ff0b:2e90::/28ff0b:2e9f:ffff:ffff:ffff:ffff:ffff:ffff
235ff0b:2ea0::/28ff0b:2eaf:ffff:ffff:ffff:ffff:ffff:ffff
236ff0b:2eb0::/28ff0b:2ebf:ffff:ffff:ffff:ffff:ffff:ffff
237ff0b:2ec0::/28ff0b:2ecf:ffff:ffff:ffff:ffff:ffff:ffff
238ff0b:2ed0::/28ff0b:2edf:ffff:ffff:ffff:ffff:ffff:ffff
239ff0b:2ee0::/28ff0b:2eef:ffff:ffff:ffff:ffff:ffff:ffff
240ff0b:2ef0::/28ff0b:2eff:ffff:ffff:ffff:ffff:ffff:ffff
241ff0b:2f00::/28ff0b:2f0f:ffff:ffff:ffff:ffff:ffff:ffff
242ff0b:2f10::/28ff0b:2f1f:ffff:ffff:ffff:ffff:ffff:ffff
243ff0b:2f20::/28ff0b:2f2f:ffff:ffff:ffff:ffff:ffff:ffff
244ff0b:2f30::/28ff0b:2f3f:ffff:ffff:ffff:ffff:ffff:ffff
245ff0b:2f40::/28ff0b:2f4f:ffff:ffff:ffff:ffff:ffff:ffff
246ff0b:2f50::/28ff0b:2f5f:ffff:ffff:ffff:ffff:ffff:ffff
247ff0b:2f60::/28ff0b:2f6f:ffff:ffff:ffff:ffff:ffff:ffff
248ff0b:2f70::/28ff0b:2f7f:ffff:ffff:ffff:ffff:ffff:ffff
249ff0b:2f80::/28ff0b:2f8f:ffff:ffff:ffff:ffff:ffff:ffff
250ff0b:2f90::/28ff0b:2f9f:ffff:ffff:ffff:ffff:ffff:ffff
251ff0b:2fa0::/28ff0b:2faf:ffff:ffff:ffff:ffff:ffff:ffff
252ff0b:2fb0::/28ff0b:2fbf:ffff:ffff:ffff:ffff:ffff:ffff
253ff0b:2fc0::/28ff0b:2fcf:ffff:ffff:ffff:ffff:ffff:ffff
254ff0b:2fd0::/28ff0b:2fdf:ffff:ffff:ffff:ffff:ffff:ffff
255ff0b:2fe0::/28ff0b:2fef:ffff:ffff:ffff:ffff:ffff:ffff
256ff0b:2ff0::/28ff0b:2fff: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.