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/48
Addresses2^80
/64 networks65,536
Network
287c:c2:dddb::/48
First address
287c:c2:dddb::
Last address
287c:c2:dddb:ffff:ffff:ffff:ffff:ffff
Addresses
1,208,925,819,614,629,174,706,176 (2^80)
/64 networks (LANs)
65,536
Full form
287c:00c2:dddb:0000:0000:0000:0000:0000
Type
Global unicast 2000::/3
Public internet addresses
Reverse DNS zone
b.d.d.d.2.c.0.0.c.7.8.2.ip6.arpa
Split into smaller subnets/56
/49 (2)/50 (4)/51 (8)/52 (16)/56 (256)/60 (4,096)/64 (65,536)

287c:c2:dddb::/48 makes 256 subnets of /56.

Subnets
#SubnetLast address
1287c:c2:dddb::/56287c:c2:dddb:ff:ffff:ffff:ffff:ffff
2287c:c2:dddb:100::/56287c:c2:dddb:1ff:ffff:ffff:ffff:ffff
3287c:c2:dddb:200::/56287c:c2:dddb:2ff:ffff:ffff:ffff:ffff
4287c:c2:dddb:300::/56287c:c2:dddb:3ff:ffff:ffff:ffff:ffff
5287c:c2:dddb:400::/56287c:c2:dddb:4ff:ffff:ffff:ffff:ffff
6287c:c2:dddb:500::/56287c:c2:dddb:5ff:ffff:ffff:ffff:ffff
7287c:c2:dddb:600::/56287c:c2:dddb:6ff:ffff:ffff:ffff:ffff
8287c:c2:dddb:700::/56287c:c2:dddb:7ff:ffff:ffff:ffff:ffff
9287c:c2:dddb:800::/56287c:c2:dddb:8ff:ffff:ffff:ffff:ffff
10287c:c2:dddb:900::/56287c:c2:dddb:9ff:ffff:ffff:ffff:ffff
11287c:c2:dddb:a00::/56287c:c2:dddb:aff:ffff:ffff:ffff:ffff
12287c:c2:dddb:b00::/56287c:c2:dddb:bff:ffff:ffff:ffff:ffff
13287c:c2:dddb:c00::/56287c:c2:dddb:cff:ffff:ffff:ffff:ffff
14287c:c2:dddb:d00::/56287c:c2:dddb:dff:ffff:ffff:ffff:ffff
15287c:c2:dddb:e00::/56287c:c2:dddb:eff:ffff:ffff:ffff:ffff
16287c:c2:dddb:f00::/56287c:c2:dddb:fff:ffff:ffff:ffff:ffff
17287c:c2:dddb:1000::/56287c:c2:dddb:10ff:ffff:ffff:ffff:ffff
18287c:c2:dddb:1100::/56287c:c2:dddb:11ff:ffff:ffff:ffff:ffff
19287c:c2:dddb:1200::/56287c:c2:dddb:12ff:ffff:ffff:ffff:ffff
20287c:c2:dddb:1300::/56287c:c2:dddb:13ff:ffff:ffff:ffff:ffff
21287c:c2:dddb:1400::/56287c:c2:dddb:14ff:ffff:ffff:ffff:ffff
22287c:c2:dddb:1500::/56287c:c2:dddb:15ff:ffff:ffff:ffff:ffff
23287c:c2:dddb:1600::/56287c:c2:dddb:16ff:ffff:ffff:ffff:ffff
24287c:c2:dddb:1700::/56287c:c2:dddb:17ff:ffff:ffff:ffff:ffff
25287c:c2:dddb:1800::/56287c:c2:dddb:18ff:ffff:ffff:ffff:ffff
26287c:c2:dddb:1900::/56287c:c2:dddb:19ff:ffff:ffff:ffff:ffff
27287c:c2:dddb:1a00::/56287c:c2:dddb:1aff:ffff:ffff:ffff:ffff
28287c:c2:dddb:1b00::/56287c:c2:dddb:1bff:ffff:ffff:ffff:ffff
29287c:c2:dddb:1c00::/56287c:c2:dddb:1cff:ffff:ffff:ffff:ffff
30287c:c2:dddb:1d00::/56287c:c2:dddb:1dff:ffff:ffff:ffff:ffff
31287c:c2:dddb:1e00::/56287c:c2:dddb:1eff:ffff:ffff:ffff:ffff
32287c:c2:dddb:1f00::/56287c:c2:dddb:1fff:ffff:ffff:ffff:ffff
33287c:c2:dddb:2000::/56287c:c2:dddb:20ff:ffff:ffff:ffff:ffff
34287c:c2:dddb:2100::/56287c:c2:dddb:21ff:ffff:ffff:ffff:ffff
35287c:c2:dddb:2200::/56287c:c2:dddb:22ff:ffff:ffff:ffff:ffff
36287c:c2:dddb:2300::/56287c:c2:dddb:23ff:ffff:ffff:ffff:ffff
37287c:c2:dddb:2400::/56287c:c2:dddb:24ff:ffff:ffff:ffff:ffff
38287c:c2:dddb:2500::/56287c:c2:dddb:25ff:ffff:ffff:ffff:ffff
39287c:c2:dddb:2600::/56287c:c2:dddb:26ff:ffff:ffff:ffff:ffff
40287c:c2:dddb:2700::/56287c:c2:dddb:27ff:ffff:ffff:ffff:ffff
41287c:c2:dddb:2800::/56287c:c2:dddb:28ff:ffff:ffff:ffff:ffff
42287c:c2:dddb:2900::/56287c:c2:dddb:29ff:ffff:ffff:ffff:ffff
43287c:c2:dddb:2a00::/56287c:c2:dddb:2aff:ffff:ffff:ffff:ffff
44287c:c2:dddb:2b00::/56287c:c2:dddb:2bff:ffff:ffff:ffff:ffff
45287c:c2:dddb:2c00::/56287c:c2:dddb:2cff:ffff:ffff:ffff:ffff
46287c:c2:dddb:2d00::/56287c:c2:dddb:2dff:ffff:ffff:ffff:ffff
47287c:c2:dddb:2e00::/56287c:c2:dddb:2eff:ffff:ffff:ffff:ffff
48287c:c2:dddb:2f00::/56287c:c2:dddb:2fff:ffff:ffff:ffff:ffff
49287c:c2:dddb:3000::/56287c:c2:dddb:30ff:ffff:ffff:ffff:ffff
50287c:c2:dddb:3100::/56287c:c2:dddb:31ff:ffff:ffff:ffff:ffff
51287c:c2:dddb:3200::/56287c:c2:dddb:32ff:ffff:ffff:ffff:ffff
52287c:c2:dddb:3300::/56287c:c2:dddb:33ff:ffff:ffff:ffff:ffff
53287c:c2:dddb:3400::/56287c:c2:dddb:34ff:ffff:ffff:ffff:ffff
54287c:c2:dddb:3500::/56287c:c2:dddb:35ff:ffff:ffff:ffff:ffff
55287c:c2:dddb:3600::/56287c:c2:dddb:36ff:ffff:ffff:ffff:ffff
56287c:c2:dddb:3700::/56287c:c2:dddb:37ff:ffff:ffff:ffff:ffff
57287c:c2:dddb:3800::/56287c:c2:dddb:38ff:ffff:ffff:ffff:ffff
58287c:c2:dddb:3900::/56287c:c2:dddb:39ff:ffff:ffff:ffff:ffff
59287c:c2:dddb:3a00::/56287c:c2:dddb:3aff:ffff:ffff:ffff:ffff
60287c:c2:dddb:3b00::/56287c:c2:dddb:3bff:ffff:ffff:ffff:ffff
61287c:c2:dddb:3c00::/56287c:c2:dddb:3cff:ffff:ffff:ffff:ffff
62287c:c2:dddb:3d00::/56287c:c2:dddb:3dff:ffff:ffff:ffff:ffff
63287c:c2:dddb:3e00::/56287c:c2:dddb:3eff:ffff:ffff:ffff:ffff
64287c:c2:dddb:3f00::/56287c:c2:dddb:3fff:ffff:ffff:ffff:ffff
65287c:c2:dddb:4000::/56287c:c2:dddb:40ff:ffff:ffff:ffff:ffff
66287c:c2:dddb:4100::/56287c:c2:dddb:41ff:ffff:ffff:ffff:ffff
67287c:c2:dddb:4200::/56287c:c2:dddb:42ff:ffff:ffff:ffff:ffff
68287c:c2:dddb:4300::/56287c:c2:dddb:43ff:ffff:ffff:ffff:ffff
69287c:c2:dddb:4400::/56287c:c2:dddb:44ff:ffff:ffff:ffff:ffff
70287c:c2:dddb:4500::/56287c:c2:dddb:45ff:ffff:ffff:ffff:ffff
71287c:c2:dddb:4600::/56287c:c2:dddb:46ff:ffff:ffff:ffff:ffff
72287c:c2:dddb:4700::/56287c:c2:dddb:47ff:ffff:ffff:ffff:ffff
73287c:c2:dddb:4800::/56287c:c2:dddb:48ff:ffff:ffff:ffff:ffff
74287c:c2:dddb:4900::/56287c:c2:dddb:49ff:ffff:ffff:ffff:ffff
75287c:c2:dddb:4a00::/56287c:c2:dddb:4aff:ffff:ffff:ffff:ffff
76287c:c2:dddb:4b00::/56287c:c2:dddb:4bff:ffff:ffff:ffff:ffff
77287c:c2:dddb:4c00::/56287c:c2:dddb:4cff:ffff:ffff:ffff:ffff
78287c:c2:dddb:4d00::/56287c:c2:dddb:4dff:ffff:ffff:ffff:ffff
79287c:c2:dddb:4e00::/56287c:c2:dddb:4eff:ffff:ffff:ffff:ffff
80287c:c2:dddb:4f00::/56287c:c2:dddb:4fff:ffff:ffff:ffff:ffff
81287c:c2:dddb:5000::/56287c:c2:dddb:50ff:ffff:ffff:ffff:ffff
82287c:c2:dddb:5100::/56287c:c2:dddb:51ff:ffff:ffff:ffff:ffff
83287c:c2:dddb:5200::/56287c:c2:dddb:52ff:ffff:ffff:ffff:ffff
84287c:c2:dddb:5300::/56287c:c2:dddb:53ff:ffff:ffff:ffff:ffff
85287c:c2:dddb:5400::/56287c:c2:dddb:54ff:ffff:ffff:ffff:ffff
86287c:c2:dddb:5500::/56287c:c2:dddb:55ff:ffff:ffff:ffff:ffff
87287c:c2:dddb:5600::/56287c:c2:dddb:56ff:ffff:ffff:ffff:ffff
88287c:c2:dddb:5700::/56287c:c2:dddb:57ff:ffff:ffff:ffff:ffff
89287c:c2:dddb:5800::/56287c:c2:dddb:58ff:ffff:ffff:ffff:ffff
90287c:c2:dddb:5900::/56287c:c2:dddb:59ff:ffff:ffff:ffff:ffff
91287c:c2:dddb:5a00::/56287c:c2:dddb:5aff:ffff:ffff:ffff:ffff
92287c:c2:dddb:5b00::/56287c:c2:dddb:5bff:ffff:ffff:ffff:ffff
93287c:c2:dddb:5c00::/56287c:c2:dddb:5cff:ffff:ffff:ffff:ffff
94287c:c2:dddb:5d00::/56287c:c2:dddb:5dff:ffff:ffff:ffff:ffff
95287c:c2:dddb:5e00::/56287c:c2:dddb:5eff:ffff:ffff:ffff:ffff
96287c:c2:dddb:5f00::/56287c:c2:dddb:5fff:ffff:ffff:ffff:ffff
97287c:c2:dddb:6000::/56287c:c2:dddb:60ff:ffff:ffff:ffff:ffff
98287c:c2:dddb:6100::/56287c:c2:dddb:61ff:ffff:ffff:ffff:ffff
99287c:c2:dddb:6200::/56287c:c2:dddb:62ff:ffff:ffff:ffff:ffff
100287c:c2:dddb:6300::/56287c:c2:dddb:63ff:ffff:ffff:ffff:ffff
101287c:c2:dddb:6400::/56287c:c2:dddb:64ff:ffff:ffff:ffff:ffff
102287c:c2:dddb:6500::/56287c:c2:dddb:65ff:ffff:ffff:ffff:ffff
103287c:c2:dddb:6600::/56287c:c2:dddb:66ff:ffff:ffff:ffff:ffff
104287c:c2:dddb:6700::/56287c:c2:dddb:67ff:ffff:ffff:ffff:ffff
105287c:c2:dddb:6800::/56287c:c2:dddb:68ff:ffff:ffff:ffff:ffff
106287c:c2:dddb:6900::/56287c:c2:dddb:69ff:ffff:ffff:ffff:ffff
107287c:c2:dddb:6a00::/56287c:c2:dddb:6aff:ffff:ffff:ffff:ffff
108287c:c2:dddb:6b00::/56287c:c2:dddb:6bff:ffff:ffff:ffff:ffff
109287c:c2:dddb:6c00::/56287c:c2:dddb:6cff:ffff:ffff:ffff:ffff
110287c:c2:dddb:6d00::/56287c:c2:dddb:6dff:ffff:ffff:ffff:ffff
111287c:c2:dddb:6e00::/56287c:c2:dddb:6eff:ffff:ffff:ffff:ffff
112287c:c2:dddb:6f00::/56287c:c2:dddb:6fff:ffff:ffff:ffff:ffff
113287c:c2:dddb:7000::/56287c:c2:dddb:70ff:ffff:ffff:ffff:ffff
114287c:c2:dddb:7100::/56287c:c2:dddb:71ff:ffff:ffff:ffff:ffff
115287c:c2:dddb:7200::/56287c:c2:dddb:72ff:ffff:ffff:ffff:ffff
116287c:c2:dddb:7300::/56287c:c2:dddb:73ff:ffff:ffff:ffff:ffff
117287c:c2:dddb:7400::/56287c:c2:dddb:74ff:ffff:ffff:ffff:ffff
118287c:c2:dddb:7500::/56287c:c2:dddb:75ff:ffff:ffff:ffff:ffff
119287c:c2:dddb:7600::/56287c:c2:dddb:76ff:ffff:ffff:ffff:ffff
120287c:c2:dddb:7700::/56287c:c2:dddb:77ff:ffff:ffff:ffff:ffff
121287c:c2:dddb:7800::/56287c:c2:dddb:78ff:ffff:ffff:ffff:ffff
122287c:c2:dddb:7900::/56287c:c2:dddb:79ff:ffff:ffff:ffff:ffff
123287c:c2:dddb:7a00::/56287c:c2:dddb:7aff:ffff:ffff:ffff:ffff
124287c:c2:dddb:7b00::/56287c:c2:dddb:7bff:ffff:ffff:ffff:ffff
125287c:c2:dddb:7c00::/56287c:c2:dddb:7cff:ffff:ffff:ffff:ffff
126287c:c2:dddb:7d00::/56287c:c2:dddb:7dff:ffff:ffff:ffff:ffff
127287c:c2:dddb:7e00::/56287c:c2:dddb:7eff:ffff:ffff:ffff:ffff
128287c:c2:dddb:7f00::/56287c:c2:dddb:7fff:ffff:ffff:ffff:ffff
129287c:c2:dddb:8000::/56287c:c2:dddb:80ff:ffff:ffff:ffff:ffff
130287c:c2:dddb:8100::/56287c:c2:dddb:81ff:ffff:ffff:ffff:ffff
131287c:c2:dddb:8200::/56287c:c2:dddb:82ff:ffff:ffff:ffff:ffff
132287c:c2:dddb:8300::/56287c:c2:dddb:83ff:ffff:ffff:ffff:ffff
133287c:c2:dddb:8400::/56287c:c2:dddb:84ff:ffff:ffff:ffff:ffff
134287c:c2:dddb:8500::/56287c:c2:dddb:85ff:ffff:ffff:ffff:ffff
135287c:c2:dddb:8600::/56287c:c2:dddb:86ff:ffff:ffff:ffff:ffff
136287c:c2:dddb:8700::/56287c:c2:dddb:87ff:ffff:ffff:ffff:ffff
137287c:c2:dddb:8800::/56287c:c2:dddb:88ff:ffff:ffff:ffff:ffff
138287c:c2:dddb:8900::/56287c:c2:dddb:89ff:ffff:ffff:ffff:ffff
139287c:c2:dddb:8a00::/56287c:c2:dddb:8aff:ffff:ffff:ffff:ffff
140287c:c2:dddb:8b00::/56287c:c2:dddb:8bff:ffff:ffff:ffff:ffff
141287c:c2:dddb:8c00::/56287c:c2:dddb:8cff:ffff:ffff:ffff:ffff
142287c:c2:dddb:8d00::/56287c:c2:dddb:8dff:ffff:ffff:ffff:ffff
143287c:c2:dddb:8e00::/56287c:c2:dddb:8eff:ffff:ffff:ffff:ffff
144287c:c2:dddb:8f00::/56287c:c2:dddb:8fff:ffff:ffff:ffff:ffff
145287c:c2:dddb:9000::/56287c:c2:dddb:90ff:ffff:ffff:ffff:ffff
146287c:c2:dddb:9100::/56287c:c2:dddb:91ff:ffff:ffff:ffff:ffff
147287c:c2:dddb:9200::/56287c:c2:dddb:92ff:ffff:ffff:ffff:ffff
148287c:c2:dddb:9300::/56287c:c2:dddb:93ff:ffff:ffff:ffff:ffff
149287c:c2:dddb:9400::/56287c:c2:dddb:94ff:ffff:ffff:ffff:ffff
150287c:c2:dddb:9500::/56287c:c2:dddb:95ff:ffff:ffff:ffff:ffff
151287c:c2:dddb:9600::/56287c:c2:dddb:96ff:ffff:ffff:ffff:ffff
152287c:c2:dddb:9700::/56287c:c2:dddb:97ff:ffff:ffff:ffff:ffff
153287c:c2:dddb:9800::/56287c:c2:dddb:98ff:ffff:ffff:ffff:ffff
154287c:c2:dddb:9900::/56287c:c2:dddb:99ff:ffff:ffff:ffff:ffff
155287c:c2:dddb:9a00::/56287c:c2:dddb:9aff:ffff:ffff:ffff:ffff
156287c:c2:dddb:9b00::/56287c:c2:dddb:9bff:ffff:ffff:ffff:ffff
157287c:c2:dddb:9c00::/56287c:c2:dddb:9cff:ffff:ffff:ffff:ffff
158287c:c2:dddb:9d00::/56287c:c2:dddb:9dff:ffff:ffff:ffff:ffff
159287c:c2:dddb:9e00::/56287c:c2:dddb:9eff:ffff:ffff:ffff:ffff
160287c:c2:dddb:9f00::/56287c:c2:dddb:9fff:ffff:ffff:ffff:ffff
161287c:c2:dddb:a000::/56287c:c2:dddb:a0ff:ffff:ffff:ffff:ffff
162287c:c2:dddb:a100::/56287c:c2:dddb:a1ff:ffff:ffff:ffff:ffff
163287c:c2:dddb:a200::/56287c:c2:dddb:a2ff:ffff:ffff:ffff:ffff
164287c:c2:dddb:a300::/56287c:c2:dddb:a3ff:ffff:ffff:ffff:ffff
165287c:c2:dddb:a400::/56287c:c2:dddb:a4ff:ffff:ffff:ffff:ffff
166287c:c2:dddb:a500::/56287c:c2:dddb:a5ff:ffff:ffff:ffff:ffff
167287c:c2:dddb:a600::/56287c:c2:dddb:a6ff:ffff:ffff:ffff:ffff
168287c:c2:dddb:a700::/56287c:c2:dddb:a7ff:ffff:ffff:ffff:ffff
169287c:c2:dddb:a800::/56287c:c2:dddb:a8ff:ffff:ffff:ffff:ffff
170287c:c2:dddb:a900::/56287c:c2:dddb:a9ff:ffff:ffff:ffff:ffff
171287c:c2:dddb:aa00::/56287c:c2:dddb:aaff:ffff:ffff:ffff:ffff
172287c:c2:dddb:ab00::/56287c:c2:dddb:abff:ffff:ffff:ffff:ffff
173287c:c2:dddb:ac00::/56287c:c2:dddb:acff:ffff:ffff:ffff:ffff
174287c:c2:dddb:ad00::/56287c:c2:dddb:adff:ffff:ffff:ffff:ffff
175287c:c2:dddb:ae00::/56287c:c2:dddb:aeff:ffff:ffff:ffff:ffff
176287c:c2:dddb:af00::/56287c:c2:dddb:afff:ffff:ffff:ffff:ffff
177287c:c2:dddb:b000::/56287c:c2:dddb:b0ff:ffff:ffff:ffff:ffff
178287c:c2:dddb:b100::/56287c:c2:dddb:b1ff:ffff:ffff:ffff:ffff
179287c:c2:dddb:b200::/56287c:c2:dddb:b2ff:ffff:ffff:ffff:ffff
180287c:c2:dddb:b300::/56287c:c2:dddb:b3ff:ffff:ffff:ffff:ffff
181287c:c2:dddb:b400::/56287c:c2:dddb:b4ff:ffff:ffff:ffff:ffff
182287c:c2:dddb:b500::/56287c:c2:dddb:b5ff:ffff:ffff:ffff:ffff
183287c:c2:dddb:b600::/56287c:c2:dddb:b6ff:ffff:ffff:ffff:ffff
184287c:c2:dddb:b700::/56287c:c2:dddb:b7ff:ffff:ffff:ffff:ffff
185287c:c2:dddb:b800::/56287c:c2:dddb:b8ff:ffff:ffff:ffff:ffff
186287c:c2:dddb:b900::/56287c:c2:dddb:b9ff:ffff:ffff:ffff:ffff
187287c:c2:dddb:ba00::/56287c:c2:dddb:baff:ffff:ffff:ffff:ffff
188287c:c2:dddb:bb00::/56287c:c2:dddb:bbff:ffff:ffff:ffff:ffff
189287c:c2:dddb:bc00::/56287c:c2:dddb:bcff:ffff:ffff:ffff:ffff
190287c:c2:dddb:bd00::/56287c:c2:dddb:bdff:ffff:ffff:ffff:ffff
191287c:c2:dddb:be00::/56287c:c2:dddb:beff:ffff:ffff:ffff:ffff
192287c:c2:dddb:bf00::/56287c:c2:dddb:bfff:ffff:ffff:ffff:ffff
193287c:c2:dddb:c000::/56287c:c2:dddb:c0ff:ffff:ffff:ffff:ffff
194287c:c2:dddb:c100::/56287c:c2:dddb:c1ff:ffff:ffff:ffff:ffff
195287c:c2:dddb:c200::/56287c:c2:dddb:c2ff:ffff:ffff:ffff:ffff
196287c:c2:dddb:c300::/56287c:c2:dddb:c3ff:ffff:ffff:ffff:ffff
197287c:c2:dddb:c400::/56287c:c2:dddb:c4ff:ffff:ffff:ffff:ffff
198287c:c2:dddb:c500::/56287c:c2:dddb:c5ff:ffff:ffff:ffff:ffff
199287c:c2:dddb:c600::/56287c:c2:dddb:c6ff:ffff:ffff:ffff:ffff
200287c:c2:dddb:c700::/56287c:c2:dddb:c7ff:ffff:ffff:ffff:ffff
201287c:c2:dddb:c800::/56287c:c2:dddb:c8ff:ffff:ffff:ffff:ffff
202287c:c2:dddb:c900::/56287c:c2:dddb:c9ff:ffff:ffff:ffff:ffff
203287c:c2:dddb:ca00::/56287c:c2:dddb:caff:ffff:ffff:ffff:ffff
204287c:c2:dddb:cb00::/56287c:c2:dddb:cbff:ffff:ffff:ffff:ffff
205287c:c2:dddb:cc00::/56287c:c2:dddb:ccff:ffff:ffff:ffff:ffff
206287c:c2:dddb:cd00::/56287c:c2:dddb:cdff:ffff:ffff:ffff:ffff
207287c:c2:dddb:ce00::/56287c:c2:dddb:ceff:ffff:ffff:ffff:ffff
208287c:c2:dddb:cf00::/56287c:c2:dddb:cfff:ffff:ffff:ffff:ffff
209287c:c2:dddb:d000::/56287c:c2:dddb:d0ff:ffff:ffff:ffff:ffff
210287c:c2:dddb:d100::/56287c:c2:dddb:d1ff:ffff:ffff:ffff:ffff
211287c:c2:dddb:d200::/56287c:c2:dddb:d2ff:ffff:ffff:ffff:ffff
212287c:c2:dddb:d300::/56287c:c2:dddb:d3ff:ffff:ffff:ffff:ffff
213287c:c2:dddb:d400::/56287c:c2:dddb:d4ff:ffff:ffff:ffff:ffff
214287c:c2:dddb:d500::/56287c:c2:dddb:d5ff:ffff:ffff:ffff:ffff
215287c:c2:dddb:d600::/56287c:c2:dddb:d6ff:ffff:ffff:ffff:ffff
216287c:c2:dddb:d700::/56287c:c2:dddb:d7ff:ffff:ffff:ffff:ffff
217287c:c2:dddb:d800::/56287c:c2:dddb:d8ff:ffff:ffff:ffff:ffff
218287c:c2:dddb:d900::/56287c:c2:dddb:d9ff:ffff:ffff:ffff:ffff
219287c:c2:dddb:da00::/56287c:c2:dddb:daff:ffff:ffff:ffff:ffff
220287c:c2:dddb:db00::/56287c:c2:dddb:dbff:ffff:ffff:ffff:ffff
221287c:c2:dddb:dc00::/56287c:c2:dddb:dcff:ffff:ffff:ffff:ffff
222287c:c2:dddb:dd00::/56287c:c2:dddb:ddff:ffff:ffff:ffff:ffff
223287c:c2:dddb:de00::/56287c:c2:dddb:deff:ffff:ffff:ffff:ffff
224287c:c2:dddb:df00::/56287c:c2:dddb:dfff:ffff:ffff:ffff:ffff
225287c:c2:dddb:e000::/56287c:c2:dddb:e0ff:ffff:ffff:ffff:ffff
226287c:c2:dddb:e100::/56287c:c2:dddb:e1ff:ffff:ffff:ffff:ffff
227287c:c2:dddb:e200::/56287c:c2:dddb:e2ff:ffff:ffff:ffff:ffff
228287c:c2:dddb:e300::/56287c:c2:dddb:e3ff:ffff:ffff:ffff:ffff
229287c:c2:dddb:e400::/56287c:c2:dddb:e4ff:ffff:ffff:ffff:ffff
230287c:c2:dddb:e500::/56287c:c2:dddb:e5ff:ffff:ffff:ffff:ffff
231287c:c2:dddb:e600::/56287c:c2:dddb:e6ff:ffff:ffff:ffff:ffff
232287c:c2:dddb:e700::/56287c:c2:dddb:e7ff:ffff:ffff:ffff:ffff
233287c:c2:dddb:e800::/56287c:c2:dddb:e8ff:ffff:ffff:ffff:ffff
234287c:c2:dddb:e900::/56287c:c2:dddb:e9ff:ffff:ffff:ffff:ffff
235287c:c2:dddb:ea00::/56287c:c2:dddb:eaff:ffff:ffff:ffff:ffff
236287c:c2:dddb:eb00::/56287c:c2:dddb:ebff:ffff:ffff:ffff:ffff
237287c:c2:dddb:ec00::/56287c:c2:dddb:ecff:ffff:ffff:ffff:ffff
238287c:c2:dddb:ed00::/56287c:c2:dddb:edff:ffff:ffff:ffff:ffff
239287c:c2:dddb:ee00::/56287c:c2:dddb:eeff:ffff:ffff:ffff:ffff
240287c:c2:dddb:ef00::/56287c:c2:dddb:efff:ffff:ffff:ffff:ffff
241287c:c2:dddb:f000::/56287c:c2:dddb:f0ff:ffff:ffff:ffff:ffff
242287c:c2:dddb:f100::/56287c:c2:dddb:f1ff:ffff:ffff:ffff:ffff
243287c:c2:dddb:f200::/56287c:c2:dddb:f2ff:ffff:ffff:ffff:ffff
244287c:c2:dddb:f300::/56287c:c2:dddb:f3ff:ffff:ffff:ffff:ffff
245287c:c2:dddb:f400::/56287c:c2:dddb:f4ff:ffff:ffff:ffff:ffff
246287c:c2:dddb:f500::/56287c:c2:dddb:f5ff:ffff:ffff:ffff:ffff
247287c:c2:dddb:f600::/56287c:c2:dddb:f6ff:ffff:ffff:ffff:ffff
248287c:c2:dddb:f700::/56287c:c2:dddb:f7ff:ffff:ffff:ffff:ffff
249287c:c2:dddb:f800::/56287c:c2:dddb:f8ff:ffff:ffff:ffff:ffff
250287c:c2:dddb:f900::/56287c:c2:dddb:f9ff:ffff:ffff:ffff:ffff
251287c:c2:dddb:fa00::/56287c:c2:dddb:faff:ffff:ffff:ffff:ffff
252287c:c2:dddb:fb00::/56287c:c2:dddb:fbff:ffff:ffff:ffff:ffff
253287c:c2:dddb:fc00::/56287c:c2:dddb:fcff:ffff:ffff:ffff:ffff
254287c:c2:dddb:fd00::/56287c:c2:dddb:fdff:ffff:ffff:ffff:ffff
255287c:c2:dddb:fe00::/56287c:c2:dddb:feff:ffff:ffff:ffff:ffff
256287c:c2:dddb:ff00::/56287c:c2:dddb: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.