Speed and call quality testMy IP addressIP subnet calculatorDNS reportWhoIs lookupRemote support

Internet and network

Speed and call quality testTest delay, jitter and speed, with a focus on phone calls.My IP addressYour public IPv4 and IPv6 addresses, provider and address range.WhoIs lookupWho owns a domain or IP address, when it expires, and its DNS.DNS reportEvery DNS record for a domain, with email setup checked.IP subnet calculatorWork out a network's range, mask and hosts, and split it into subnets.

Computers and devices

Update checkIs this computer, phone and browser up to date? With links to update.Camera and mic testCheck your webcam and microphone before a call.Test print pagePrint an A4 page to check a printer: edges, text, line art and colours.

Make and print

Clean textStrip hidden characters, smart quotes and odd spaces from pasted text.QR code makerMake a QR code for a link, contact or message. Nothing leaves your browser.Wi-Fi QR posterPrint an A4 poster that lets guests join your Wi-Fi by scanning.

Surftec support

Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

Surftec websiteServices, news and how to contact Surftec
Cloud Tools
Guest
GuestNot signed in

Surftec customers will be recognised automatically when they use these tools from their office network.

Customer sign-in is coming soon.

IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Prefix/24
Addresses2^104
/64 networks2^40
Network
ff8a:dd00::/24
First address
ff8a:dd00::
Last address
ff8a:ddff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
20,282,409,603,651,670,423,947,251,286,016 (2^104)
/64 networks (LANs)
1,099,511,627,776 (2^40)
Full form
ff8a:dd00:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
d.d.a.8.f.f.ip6.arpa
Split into smaller subnets/40
/25 (2)/26 (4)/27 (8)/28 (16)/32 (256)/36 (4,096)/40 (65,536)

ff8a:dd00::/24 makes 65,536 subnets of /40; the first 256 are listed.

Subnets
#SubnetLast address
1ff8a:dd00::/40ff8a:dd00:ff:ffff:ffff:ffff:ffff:ffff
2ff8a:dd00:100::/40ff8a:dd00:1ff:ffff:ffff:ffff:ffff:ffff
3ff8a:dd00:200::/40ff8a:dd00:2ff:ffff:ffff:ffff:ffff:ffff
4ff8a:dd00:300::/40ff8a:dd00:3ff:ffff:ffff:ffff:ffff:ffff
5ff8a:dd00:400::/40ff8a:dd00:4ff:ffff:ffff:ffff:ffff:ffff
6ff8a:dd00:500::/40ff8a:dd00:5ff:ffff:ffff:ffff:ffff:ffff
7ff8a:dd00:600::/40ff8a:dd00:6ff:ffff:ffff:ffff:ffff:ffff
8ff8a:dd00:700::/40ff8a:dd00:7ff:ffff:ffff:ffff:ffff:ffff
9ff8a:dd00:800::/40ff8a:dd00:8ff:ffff:ffff:ffff:ffff:ffff
10ff8a:dd00:900::/40ff8a:dd00:9ff:ffff:ffff:ffff:ffff:ffff
11ff8a:dd00:a00::/40ff8a:dd00:aff:ffff:ffff:ffff:ffff:ffff
12ff8a:dd00:b00::/40ff8a:dd00:bff:ffff:ffff:ffff:ffff:ffff
13ff8a:dd00:c00::/40ff8a:dd00:cff:ffff:ffff:ffff:ffff:ffff
14ff8a:dd00:d00::/40ff8a:dd00:dff:ffff:ffff:ffff:ffff:ffff
15ff8a:dd00:e00::/40ff8a:dd00:eff:ffff:ffff:ffff:ffff:ffff
16ff8a:dd00:f00::/40ff8a:dd00:fff:ffff:ffff:ffff:ffff:ffff
17ff8a:dd00:1000::/40ff8a:dd00:10ff:ffff:ffff:ffff:ffff:ffff
18ff8a:dd00:1100::/40ff8a:dd00:11ff:ffff:ffff:ffff:ffff:ffff
19ff8a:dd00:1200::/40ff8a:dd00:12ff:ffff:ffff:ffff:ffff:ffff
20ff8a:dd00:1300::/40ff8a:dd00:13ff:ffff:ffff:ffff:ffff:ffff
21ff8a:dd00:1400::/40ff8a:dd00:14ff:ffff:ffff:ffff:ffff:ffff
22ff8a:dd00:1500::/40ff8a:dd00:15ff:ffff:ffff:ffff:ffff:ffff
23ff8a:dd00:1600::/40ff8a:dd00:16ff:ffff:ffff:ffff:ffff:ffff
24ff8a:dd00:1700::/40ff8a:dd00:17ff:ffff:ffff:ffff:ffff:ffff
25ff8a:dd00:1800::/40ff8a:dd00:18ff:ffff:ffff:ffff:ffff:ffff
26ff8a:dd00:1900::/40ff8a:dd00:19ff:ffff:ffff:ffff:ffff:ffff
27ff8a:dd00:1a00::/40ff8a:dd00:1aff:ffff:ffff:ffff:ffff:ffff
28ff8a:dd00:1b00::/40ff8a:dd00:1bff:ffff:ffff:ffff:ffff:ffff
29ff8a:dd00:1c00::/40ff8a:dd00:1cff:ffff:ffff:ffff:ffff:ffff
30ff8a:dd00:1d00::/40ff8a:dd00:1dff:ffff:ffff:ffff:ffff:ffff
31ff8a:dd00:1e00::/40ff8a:dd00:1eff:ffff:ffff:ffff:ffff:ffff
32ff8a:dd00:1f00::/40ff8a:dd00:1fff:ffff:ffff:ffff:ffff:ffff
33ff8a:dd00:2000::/40ff8a:dd00:20ff:ffff:ffff:ffff:ffff:ffff
34ff8a:dd00:2100::/40ff8a:dd00:21ff:ffff:ffff:ffff:ffff:ffff
35ff8a:dd00:2200::/40ff8a:dd00:22ff:ffff:ffff:ffff:ffff:ffff
36ff8a:dd00:2300::/40ff8a:dd00:23ff:ffff:ffff:ffff:ffff:ffff
37ff8a:dd00:2400::/40ff8a:dd00:24ff:ffff:ffff:ffff:ffff:ffff
38ff8a:dd00:2500::/40ff8a:dd00:25ff:ffff:ffff:ffff:ffff:ffff
39ff8a:dd00:2600::/40ff8a:dd00:26ff:ffff:ffff:ffff:ffff:ffff
40ff8a:dd00:2700::/40ff8a:dd00:27ff:ffff:ffff:ffff:ffff:ffff
41ff8a:dd00:2800::/40ff8a:dd00:28ff:ffff:ffff:ffff:ffff:ffff
42ff8a:dd00:2900::/40ff8a:dd00:29ff:ffff:ffff:ffff:ffff:ffff
43ff8a:dd00:2a00::/40ff8a:dd00:2aff:ffff:ffff:ffff:ffff:ffff
44ff8a:dd00:2b00::/40ff8a:dd00:2bff:ffff:ffff:ffff:ffff:ffff
45ff8a:dd00:2c00::/40ff8a:dd00:2cff:ffff:ffff:ffff:ffff:ffff
46ff8a:dd00:2d00::/40ff8a:dd00:2dff:ffff:ffff:ffff:ffff:ffff
47ff8a:dd00:2e00::/40ff8a:dd00:2eff:ffff:ffff:ffff:ffff:ffff
48ff8a:dd00:2f00::/40ff8a:dd00:2fff:ffff:ffff:ffff:ffff:ffff
49ff8a:dd00:3000::/40ff8a:dd00:30ff:ffff:ffff:ffff:ffff:ffff
50ff8a:dd00:3100::/40ff8a:dd00:31ff:ffff:ffff:ffff:ffff:ffff
51ff8a:dd00:3200::/40ff8a:dd00:32ff:ffff:ffff:ffff:ffff:ffff
52ff8a:dd00:3300::/40ff8a:dd00:33ff:ffff:ffff:ffff:ffff:ffff
53ff8a:dd00:3400::/40ff8a:dd00:34ff:ffff:ffff:ffff:ffff:ffff
54ff8a:dd00:3500::/40ff8a:dd00:35ff:ffff:ffff:ffff:ffff:ffff
55ff8a:dd00:3600::/40ff8a:dd00:36ff:ffff:ffff:ffff:ffff:ffff
56ff8a:dd00:3700::/40ff8a:dd00:37ff:ffff:ffff:ffff:ffff:ffff
57ff8a:dd00:3800::/40ff8a:dd00:38ff:ffff:ffff:ffff:ffff:ffff
58ff8a:dd00:3900::/40ff8a:dd00:39ff:ffff:ffff:ffff:ffff:ffff
59ff8a:dd00:3a00::/40ff8a:dd00:3aff:ffff:ffff:ffff:ffff:ffff
60ff8a:dd00:3b00::/40ff8a:dd00:3bff:ffff:ffff:ffff:ffff:ffff
61ff8a:dd00:3c00::/40ff8a:dd00:3cff:ffff:ffff:ffff:ffff:ffff
62ff8a:dd00:3d00::/40ff8a:dd00:3dff:ffff:ffff:ffff:ffff:ffff
63ff8a:dd00:3e00::/40ff8a:dd00:3eff:ffff:ffff:ffff:ffff:ffff
64ff8a:dd00:3f00::/40ff8a:dd00:3fff:ffff:ffff:ffff:ffff:ffff
65ff8a:dd00:4000::/40ff8a:dd00:40ff:ffff:ffff:ffff:ffff:ffff
66ff8a:dd00:4100::/40ff8a:dd00:41ff:ffff:ffff:ffff:ffff:ffff
67ff8a:dd00:4200::/40ff8a:dd00:42ff:ffff:ffff:ffff:ffff:ffff
68ff8a:dd00:4300::/40ff8a:dd00:43ff:ffff:ffff:ffff:ffff:ffff
69ff8a:dd00:4400::/40ff8a:dd00:44ff:ffff:ffff:ffff:ffff:ffff
70ff8a:dd00:4500::/40ff8a:dd00:45ff:ffff:ffff:ffff:ffff:ffff
71ff8a:dd00:4600::/40ff8a:dd00:46ff:ffff:ffff:ffff:ffff:ffff
72ff8a:dd00:4700::/40ff8a:dd00:47ff:ffff:ffff:ffff:ffff:ffff
73ff8a:dd00:4800::/40ff8a:dd00:48ff:ffff:ffff:ffff:ffff:ffff
74ff8a:dd00:4900::/40ff8a:dd00:49ff:ffff:ffff:ffff:ffff:ffff
75ff8a:dd00:4a00::/40ff8a:dd00:4aff:ffff:ffff:ffff:ffff:ffff
76ff8a:dd00:4b00::/40ff8a:dd00:4bff:ffff:ffff:ffff:ffff:ffff
77ff8a:dd00:4c00::/40ff8a:dd00:4cff:ffff:ffff:ffff:ffff:ffff
78ff8a:dd00:4d00::/40ff8a:dd00:4dff:ffff:ffff:ffff:ffff:ffff
79ff8a:dd00:4e00::/40ff8a:dd00:4eff:ffff:ffff:ffff:ffff:ffff
80ff8a:dd00:4f00::/40ff8a:dd00:4fff:ffff:ffff:ffff:ffff:ffff
81ff8a:dd00:5000::/40ff8a:dd00:50ff:ffff:ffff:ffff:ffff:ffff
82ff8a:dd00:5100::/40ff8a:dd00:51ff:ffff:ffff:ffff:ffff:ffff
83ff8a:dd00:5200::/40ff8a:dd00:52ff:ffff:ffff:ffff:ffff:ffff
84ff8a:dd00:5300::/40ff8a:dd00:53ff:ffff:ffff:ffff:ffff:ffff
85ff8a:dd00:5400::/40ff8a:dd00:54ff:ffff:ffff:ffff:ffff:ffff
86ff8a:dd00:5500::/40ff8a:dd00:55ff:ffff:ffff:ffff:ffff:ffff
87ff8a:dd00:5600::/40ff8a:dd00:56ff:ffff:ffff:ffff:ffff:ffff
88ff8a:dd00:5700::/40ff8a:dd00:57ff:ffff:ffff:ffff:ffff:ffff
89ff8a:dd00:5800::/40ff8a:dd00:58ff:ffff:ffff:ffff:ffff:ffff
90ff8a:dd00:5900::/40ff8a:dd00:59ff:ffff:ffff:ffff:ffff:ffff
91ff8a:dd00:5a00::/40ff8a:dd00:5aff:ffff:ffff:ffff:ffff:ffff
92ff8a:dd00:5b00::/40ff8a:dd00:5bff:ffff:ffff:ffff:ffff:ffff
93ff8a:dd00:5c00::/40ff8a:dd00:5cff:ffff:ffff:ffff:ffff:ffff
94ff8a:dd00:5d00::/40ff8a:dd00:5dff:ffff:ffff:ffff:ffff:ffff
95ff8a:dd00:5e00::/40ff8a:dd00:5eff:ffff:ffff:ffff:ffff:ffff
96ff8a:dd00:5f00::/40ff8a:dd00:5fff:ffff:ffff:ffff:ffff:ffff
97ff8a:dd00:6000::/40ff8a:dd00:60ff:ffff:ffff:ffff:ffff:ffff
98ff8a:dd00:6100::/40ff8a:dd00:61ff:ffff:ffff:ffff:ffff:ffff
99ff8a:dd00:6200::/40ff8a:dd00:62ff:ffff:ffff:ffff:ffff:ffff
100ff8a:dd00:6300::/40ff8a:dd00:63ff:ffff:ffff:ffff:ffff:ffff
101ff8a:dd00:6400::/40ff8a:dd00:64ff:ffff:ffff:ffff:ffff:ffff
102ff8a:dd00:6500::/40ff8a:dd00:65ff:ffff:ffff:ffff:ffff:ffff
103ff8a:dd00:6600::/40ff8a:dd00:66ff:ffff:ffff:ffff:ffff:ffff
104ff8a:dd00:6700::/40ff8a:dd00:67ff:ffff:ffff:ffff:ffff:ffff
105ff8a:dd00:6800::/40ff8a:dd00:68ff:ffff:ffff:ffff:ffff:ffff
106ff8a:dd00:6900::/40ff8a:dd00:69ff:ffff:ffff:ffff:ffff:ffff
107ff8a:dd00:6a00::/40ff8a:dd00:6aff:ffff:ffff:ffff:ffff:ffff
108ff8a:dd00:6b00::/40ff8a:dd00:6bff:ffff:ffff:ffff:ffff:ffff
109ff8a:dd00:6c00::/40ff8a:dd00:6cff:ffff:ffff:ffff:ffff:ffff
110ff8a:dd00:6d00::/40ff8a:dd00:6dff:ffff:ffff:ffff:ffff:ffff
111ff8a:dd00:6e00::/40ff8a:dd00:6eff:ffff:ffff:ffff:ffff:ffff
112ff8a:dd00:6f00::/40ff8a:dd00:6fff:ffff:ffff:ffff:ffff:ffff
113ff8a:dd00:7000::/40ff8a:dd00:70ff:ffff:ffff:ffff:ffff:ffff
114ff8a:dd00:7100::/40ff8a:dd00:71ff:ffff:ffff:ffff:ffff:ffff
115ff8a:dd00:7200::/40ff8a:dd00:72ff:ffff:ffff:ffff:ffff:ffff
116ff8a:dd00:7300::/40ff8a:dd00:73ff:ffff:ffff:ffff:ffff:ffff
117ff8a:dd00:7400::/40ff8a:dd00:74ff:ffff:ffff:ffff:ffff:ffff
118ff8a:dd00:7500::/40ff8a:dd00:75ff:ffff:ffff:ffff:ffff:ffff
119ff8a:dd00:7600::/40ff8a:dd00:76ff:ffff:ffff:ffff:ffff:ffff
120ff8a:dd00:7700::/40ff8a:dd00:77ff:ffff:ffff:ffff:ffff:ffff
121ff8a:dd00:7800::/40ff8a:dd00:78ff:ffff:ffff:ffff:ffff:ffff
122ff8a:dd00:7900::/40ff8a:dd00:79ff:ffff:ffff:ffff:ffff:ffff
123ff8a:dd00:7a00::/40ff8a:dd00:7aff:ffff:ffff:ffff:ffff:ffff
124ff8a:dd00:7b00::/40ff8a:dd00:7bff:ffff:ffff:ffff:ffff:ffff
125ff8a:dd00:7c00::/40ff8a:dd00:7cff:ffff:ffff:ffff:ffff:ffff
126ff8a:dd00:7d00::/40ff8a:dd00:7dff:ffff:ffff:ffff:ffff:ffff
127ff8a:dd00:7e00::/40ff8a:dd00:7eff:ffff:ffff:ffff:ffff:ffff
128ff8a:dd00:7f00::/40ff8a:dd00:7fff:ffff:ffff:ffff:ffff:ffff
129ff8a:dd00:8000::/40ff8a:dd00:80ff:ffff:ffff:ffff:ffff:ffff
130ff8a:dd00:8100::/40ff8a:dd00:81ff:ffff:ffff:ffff:ffff:ffff
131ff8a:dd00:8200::/40ff8a:dd00:82ff:ffff:ffff:ffff:ffff:ffff
132ff8a:dd00:8300::/40ff8a:dd00:83ff:ffff:ffff:ffff:ffff:ffff
133ff8a:dd00:8400::/40ff8a:dd00:84ff:ffff:ffff:ffff:ffff:ffff
134ff8a:dd00:8500::/40ff8a:dd00:85ff:ffff:ffff:ffff:ffff:ffff
135ff8a:dd00:8600::/40ff8a:dd00:86ff:ffff:ffff:ffff:ffff:ffff
136ff8a:dd00:8700::/40ff8a:dd00:87ff:ffff:ffff:ffff:ffff:ffff
137ff8a:dd00:8800::/40ff8a:dd00:88ff:ffff:ffff:ffff:ffff:ffff
138ff8a:dd00:8900::/40ff8a:dd00:89ff:ffff:ffff:ffff:ffff:ffff
139ff8a:dd00:8a00::/40ff8a:dd00:8aff:ffff:ffff:ffff:ffff:ffff
140ff8a:dd00:8b00::/40ff8a:dd00:8bff:ffff:ffff:ffff:ffff:ffff
141ff8a:dd00:8c00::/40ff8a:dd00:8cff:ffff:ffff:ffff:ffff:ffff
142ff8a:dd00:8d00::/40ff8a:dd00:8dff:ffff:ffff:ffff:ffff:ffff
143ff8a:dd00:8e00::/40ff8a:dd00:8eff:ffff:ffff:ffff:ffff:ffff
144ff8a:dd00:8f00::/40ff8a:dd00:8fff:ffff:ffff:ffff:ffff:ffff
145ff8a:dd00:9000::/40ff8a:dd00:90ff:ffff:ffff:ffff:ffff:ffff
146ff8a:dd00:9100::/40ff8a:dd00:91ff:ffff:ffff:ffff:ffff:ffff
147ff8a:dd00:9200::/40ff8a:dd00:92ff:ffff:ffff:ffff:ffff:ffff
148ff8a:dd00:9300::/40ff8a:dd00:93ff:ffff:ffff:ffff:ffff:ffff
149ff8a:dd00:9400::/40ff8a:dd00:94ff:ffff:ffff:ffff:ffff:ffff
150ff8a:dd00:9500::/40ff8a:dd00:95ff:ffff:ffff:ffff:ffff:ffff
151ff8a:dd00:9600::/40ff8a:dd00:96ff:ffff:ffff:ffff:ffff:ffff
152ff8a:dd00:9700::/40ff8a:dd00:97ff:ffff:ffff:ffff:ffff:ffff
153ff8a:dd00:9800::/40ff8a:dd00:98ff:ffff:ffff:ffff:ffff:ffff
154ff8a:dd00:9900::/40ff8a:dd00:99ff:ffff:ffff:ffff:ffff:ffff
155ff8a:dd00:9a00::/40ff8a:dd00:9aff:ffff:ffff:ffff:ffff:ffff
156ff8a:dd00:9b00::/40ff8a:dd00:9bff:ffff:ffff:ffff:ffff:ffff
157ff8a:dd00:9c00::/40ff8a:dd00:9cff:ffff:ffff:ffff:ffff:ffff
158ff8a:dd00:9d00::/40ff8a:dd00:9dff:ffff:ffff:ffff:ffff:ffff
159ff8a:dd00:9e00::/40ff8a:dd00:9eff:ffff:ffff:ffff:ffff:ffff
160ff8a:dd00:9f00::/40ff8a:dd00:9fff:ffff:ffff:ffff:ffff:ffff
161ff8a:dd00:a000::/40ff8a:dd00:a0ff:ffff:ffff:ffff:ffff:ffff
162ff8a:dd00:a100::/40ff8a:dd00:a1ff:ffff:ffff:ffff:ffff:ffff
163ff8a:dd00:a200::/40ff8a:dd00:a2ff:ffff:ffff:ffff:ffff:ffff
164ff8a:dd00:a300::/40ff8a:dd00:a3ff:ffff:ffff:ffff:ffff:ffff
165ff8a:dd00:a400::/40ff8a:dd00:a4ff:ffff:ffff:ffff:ffff:ffff
166ff8a:dd00:a500::/40ff8a:dd00:a5ff:ffff:ffff:ffff:ffff:ffff
167ff8a:dd00:a600::/40ff8a:dd00:a6ff:ffff:ffff:ffff:ffff:ffff
168ff8a:dd00:a700::/40ff8a:dd00:a7ff:ffff:ffff:ffff:ffff:ffff
169ff8a:dd00:a800::/40ff8a:dd00:a8ff:ffff:ffff:ffff:ffff:ffff
170ff8a:dd00:a900::/40ff8a:dd00:a9ff:ffff:ffff:ffff:ffff:ffff
171ff8a:dd00:aa00::/40ff8a:dd00:aaff:ffff:ffff:ffff:ffff:ffff
172ff8a:dd00:ab00::/40ff8a:dd00:abff:ffff:ffff:ffff:ffff:ffff
173ff8a:dd00:ac00::/40ff8a:dd00:acff:ffff:ffff:ffff:ffff:ffff
174ff8a:dd00:ad00::/40ff8a:dd00:adff:ffff:ffff:ffff:ffff:ffff
175ff8a:dd00:ae00::/40ff8a:dd00:aeff:ffff:ffff:ffff:ffff:ffff
176ff8a:dd00:af00::/40ff8a:dd00:afff:ffff:ffff:ffff:ffff:ffff
177ff8a:dd00:b000::/40ff8a:dd00:b0ff:ffff:ffff:ffff:ffff:ffff
178ff8a:dd00:b100::/40ff8a:dd00:b1ff:ffff:ffff:ffff:ffff:ffff
179ff8a:dd00:b200::/40ff8a:dd00:b2ff:ffff:ffff:ffff:ffff:ffff
180ff8a:dd00:b300::/40ff8a:dd00:b3ff:ffff:ffff:ffff:ffff:ffff
181ff8a:dd00:b400::/40ff8a:dd00:b4ff:ffff:ffff:ffff:ffff:ffff
182ff8a:dd00:b500::/40ff8a:dd00:b5ff:ffff:ffff:ffff:ffff:ffff
183ff8a:dd00:b600::/40ff8a:dd00:b6ff:ffff:ffff:ffff:ffff:ffff
184ff8a:dd00:b700::/40ff8a:dd00:b7ff:ffff:ffff:ffff:ffff:ffff
185ff8a:dd00:b800::/40ff8a:dd00:b8ff:ffff:ffff:ffff:ffff:ffff
186ff8a:dd00:b900::/40ff8a:dd00:b9ff:ffff:ffff:ffff:ffff:ffff
187ff8a:dd00:ba00::/40ff8a:dd00:baff:ffff:ffff:ffff:ffff:ffff
188ff8a:dd00:bb00::/40ff8a:dd00:bbff:ffff:ffff:ffff:ffff:ffff
189ff8a:dd00:bc00::/40ff8a:dd00:bcff:ffff:ffff:ffff:ffff:ffff
190ff8a:dd00:bd00::/40ff8a:dd00:bdff:ffff:ffff:ffff:ffff:ffff
191ff8a:dd00:be00::/40ff8a:dd00:beff:ffff:ffff:ffff:ffff:ffff
192ff8a:dd00:bf00::/40ff8a:dd00:bfff:ffff:ffff:ffff:ffff:ffff
193ff8a:dd00:c000::/40ff8a:dd00:c0ff:ffff:ffff:ffff:ffff:ffff
194ff8a:dd00:c100::/40ff8a:dd00:c1ff:ffff:ffff:ffff:ffff:ffff
195ff8a:dd00:c200::/40ff8a:dd00:c2ff:ffff:ffff:ffff:ffff:ffff
196ff8a:dd00:c300::/40ff8a:dd00:c3ff:ffff:ffff:ffff:ffff:ffff
197ff8a:dd00:c400::/40ff8a:dd00:c4ff:ffff:ffff:ffff:ffff:ffff
198ff8a:dd00:c500::/40ff8a:dd00:c5ff:ffff:ffff:ffff:ffff:ffff
199ff8a:dd00:c600::/40ff8a:dd00:c6ff:ffff:ffff:ffff:ffff:ffff
200ff8a:dd00:c700::/40ff8a:dd00:c7ff:ffff:ffff:ffff:ffff:ffff
201ff8a:dd00:c800::/40ff8a:dd00:c8ff:ffff:ffff:ffff:ffff:ffff
202ff8a:dd00:c900::/40ff8a:dd00:c9ff:ffff:ffff:ffff:ffff:ffff
203ff8a:dd00:ca00::/40ff8a:dd00:caff:ffff:ffff:ffff:ffff:ffff
204ff8a:dd00:cb00::/40ff8a:dd00:cbff:ffff:ffff:ffff:ffff:ffff
205ff8a:dd00:cc00::/40ff8a:dd00:ccff:ffff:ffff:ffff:ffff:ffff
206ff8a:dd00:cd00::/40ff8a:dd00:cdff:ffff:ffff:ffff:ffff:ffff
207ff8a:dd00:ce00::/40ff8a:dd00:ceff:ffff:ffff:ffff:ffff:ffff
208ff8a:dd00:cf00::/40ff8a:dd00:cfff:ffff:ffff:ffff:ffff:ffff
209ff8a:dd00:d000::/40ff8a:dd00:d0ff:ffff:ffff:ffff:ffff:ffff
210ff8a:dd00:d100::/40ff8a:dd00:d1ff:ffff:ffff:ffff:ffff:ffff
211ff8a:dd00:d200::/40ff8a:dd00:d2ff:ffff:ffff:ffff:ffff:ffff
212ff8a:dd00:d300::/40ff8a:dd00:d3ff:ffff:ffff:ffff:ffff:ffff
213ff8a:dd00:d400::/40ff8a:dd00:d4ff:ffff:ffff:ffff:ffff:ffff
214ff8a:dd00:d500::/40ff8a:dd00:d5ff:ffff:ffff:ffff:ffff:ffff
215ff8a:dd00:d600::/40ff8a:dd00:d6ff:ffff:ffff:ffff:ffff:ffff
216ff8a:dd00:d700::/40ff8a:dd00:d7ff:ffff:ffff:ffff:ffff:ffff
217ff8a:dd00:d800::/40ff8a:dd00:d8ff:ffff:ffff:ffff:ffff:ffff
218ff8a:dd00:d900::/40ff8a:dd00:d9ff:ffff:ffff:ffff:ffff:ffff
219ff8a:dd00:da00::/40ff8a:dd00:daff:ffff:ffff:ffff:ffff:ffff
220ff8a:dd00:db00::/40ff8a:dd00:dbff:ffff:ffff:ffff:ffff:ffff
221ff8a:dd00:dc00::/40ff8a:dd00:dcff:ffff:ffff:ffff:ffff:ffff
222ff8a:dd00:dd00::/40ff8a:dd00:ddff:ffff:ffff:ffff:ffff:ffff
223ff8a:dd00:de00::/40ff8a:dd00:deff:ffff:ffff:ffff:ffff:ffff
224ff8a:dd00:df00::/40ff8a:dd00:dfff:ffff:ffff:ffff:ffff:ffff
225ff8a:dd00:e000::/40ff8a:dd00:e0ff:ffff:ffff:ffff:ffff:ffff
226ff8a:dd00:e100::/40ff8a:dd00:e1ff:ffff:ffff:ffff:ffff:ffff
227ff8a:dd00:e200::/40ff8a:dd00:e2ff:ffff:ffff:ffff:ffff:ffff
228ff8a:dd00:e300::/40ff8a:dd00:e3ff:ffff:ffff:ffff:ffff:ffff
229ff8a:dd00:e400::/40ff8a:dd00:e4ff:ffff:ffff:ffff:ffff:ffff
230ff8a:dd00:e500::/40ff8a:dd00:e5ff:ffff:ffff:ffff:ffff:ffff
231ff8a:dd00:e600::/40ff8a:dd00:e6ff:ffff:ffff:ffff:ffff:ffff
232ff8a:dd00:e700::/40ff8a:dd00:e7ff:ffff:ffff:ffff:ffff:ffff
233ff8a:dd00:e800::/40ff8a:dd00:e8ff:ffff:ffff:ffff:ffff:ffff
234ff8a:dd00:e900::/40ff8a:dd00:e9ff:ffff:ffff:ffff:ffff:ffff
235ff8a:dd00:ea00::/40ff8a:dd00:eaff:ffff:ffff:ffff:ffff:ffff
236ff8a:dd00:eb00::/40ff8a:dd00:ebff:ffff:ffff:ffff:ffff:ffff
237ff8a:dd00:ec00::/40ff8a:dd00:ecff:ffff:ffff:ffff:ffff:ffff
238ff8a:dd00:ed00::/40ff8a:dd00:edff:ffff:ffff:ffff:ffff:ffff
239ff8a:dd00:ee00::/40ff8a:dd00:eeff:ffff:ffff:ffff:ffff:ffff
240ff8a:dd00:ef00::/40ff8a:dd00:efff:ffff:ffff:ffff:ffff:ffff
241ff8a:dd00:f000::/40ff8a:dd00:f0ff:ffff:ffff:ffff:ffff:ffff
242ff8a:dd00:f100::/40ff8a:dd00:f1ff:ffff:ffff:ffff:ffff:ffff
243ff8a:dd00:f200::/40ff8a:dd00:f2ff:ffff:ffff:ffff:ffff:ffff
244ff8a:dd00:f300::/40ff8a:dd00:f3ff:ffff:ffff:ffff:ffff:ffff
245ff8a:dd00:f400::/40ff8a:dd00:f4ff:ffff:ffff:ffff:ffff:ffff
246ff8a:dd00:f500::/40ff8a:dd00:f5ff:ffff:ffff:ffff:ffff:ffff
247ff8a:dd00:f600::/40ff8a:dd00:f6ff:ffff:ffff:ffff:ffff:ffff
248ff8a:dd00:f700::/40ff8a:dd00:f7ff:ffff:ffff:ffff:ffff:ffff
249ff8a:dd00:f800::/40ff8a:dd00:f8ff:ffff:ffff:ffff:ffff:ffff
250ff8a:dd00:f900::/40ff8a:dd00:f9ff:ffff:ffff:ffff:ffff:ffff
251ff8a:dd00:fa00::/40ff8a:dd00:faff:ffff:ffff:ffff:ffff:ffff
252ff8a:dd00:fb00::/40ff8a:dd00:fbff:ffff:ffff:ffff:ffff:ffff
253ff8a:dd00:fc00::/40ff8a:dd00:fcff:ffff:ffff:ffff:ffff:ffff
254ff8a:dd00:fd00::/40ff8a:dd00:fdff:ffff:ffff:ffff:ffff:ffff
255ff8a:dd00:fe00::/40ff8a:dd00:feff:ffff:ffff:ffff:ffff:ffff
256ff8a:dd00:ff00::/40ff8a:dd00: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.