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/42
Addresses2^86
/64 networks4,194,304
Network
fe80:c25a::/42
First address
fe80:c25a::
Last address
fe80:c25a:3f:ffff:ffff:ffff:ffff:ffff
Addresses
77,371,252,455,336,267,181,195,264 (2^86)
/64 networks (LANs)
4,194,304
Full form
fe80:c25a:0000:0000:0000:0000:0000:0000
Type
Link-local fe80::/10
Every IPv6 interface has one; not routed
Reverse DNS zones
0.0.0.a.5.2.c.0.8.e.f.ip6.arpa
1.0.0.a.5.2.c.0.8.e.f.ip6.arpa
2.0.0.a.5.2.c.0.8.e.f.ip6.arpa
3.0.0.a.5.2.c.0.8.e.f.ip6.arpa
/42 is not on a 4-bit boundary, so it takes 4 /44 zones.
Split into smaller subnets/56
/43 (2)/44 (4)/45 (8)/46 (16)/48 (64)/52 (1,024)/56 (16,384)

fe80:c25a::/42 makes 16,384 subnets of /56; the first 256 are listed.

Subnets
#SubnetLast address
1fe80:c25a::/56fe80:c25a:0:ff:ffff:ffff:ffff:ffff
2fe80:c25a:0:100::/56fe80:c25a:0:1ff:ffff:ffff:ffff:ffff
3fe80:c25a:0:200::/56fe80:c25a:0:2ff:ffff:ffff:ffff:ffff
4fe80:c25a:0:300::/56fe80:c25a:0:3ff:ffff:ffff:ffff:ffff
5fe80:c25a:0:400::/56fe80:c25a:0:4ff:ffff:ffff:ffff:ffff
6fe80:c25a:0:500::/56fe80:c25a:0:5ff:ffff:ffff:ffff:ffff
7fe80:c25a:0:600::/56fe80:c25a:0:6ff:ffff:ffff:ffff:ffff
8fe80:c25a:0:700::/56fe80:c25a:0:7ff:ffff:ffff:ffff:ffff
9fe80:c25a:0:800::/56fe80:c25a:0:8ff:ffff:ffff:ffff:ffff
10fe80:c25a:0:900::/56fe80:c25a:0:9ff:ffff:ffff:ffff:ffff
11fe80:c25a:0:a00::/56fe80:c25a:0:aff:ffff:ffff:ffff:ffff
12fe80:c25a:0:b00::/56fe80:c25a:0:bff:ffff:ffff:ffff:ffff
13fe80:c25a:0:c00::/56fe80:c25a:0:cff:ffff:ffff:ffff:ffff
14fe80:c25a:0:d00::/56fe80:c25a:0:dff:ffff:ffff:ffff:ffff
15fe80:c25a:0:e00::/56fe80:c25a:0:eff:ffff:ffff:ffff:ffff
16fe80:c25a:0:f00::/56fe80:c25a:0:fff:ffff:ffff:ffff:ffff
17fe80:c25a:0:1000::/56fe80:c25a:0:10ff:ffff:ffff:ffff:ffff
18fe80:c25a:0:1100::/56fe80:c25a:0:11ff:ffff:ffff:ffff:ffff
19fe80:c25a:0:1200::/56fe80:c25a:0:12ff:ffff:ffff:ffff:ffff
20fe80:c25a:0:1300::/56fe80:c25a:0:13ff:ffff:ffff:ffff:ffff
21fe80:c25a:0:1400::/56fe80:c25a:0:14ff:ffff:ffff:ffff:ffff
22fe80:c25a:0:1500::/56fe80:c25a:0:15ff:ffff:ffff:ffff:ffff
23fe80:c25a:0:1600::/56fe80:c25a:0:16ff:ffff:ffff:ffff:ffff
24fe80:c25a:0:1700::/56fe80:c25a:0:17ff:ffff:ffff:ffff:ffff
25fe80:c25a:0:1800::/56fe80:c25a:0:18ff:ffff:ffff:ffff:ffff
26fe80:c25a:0:1900::/56fe80:c25a:0:19ff:ffff:ffff:ffff:ffff
27fe80:c25a:0:1a00::/56fe80:c25a:0:1aff:ffff:ffff:ffff:ffff
28fe80:c25a:0:1b00::/56fe80:c25a:0:1bff:ffff:ffff:ffff:ffff
29fe80:c25a:0:1c00::/56fe80:c25a:0:1cff:ffff:ffff:ffff:ffff
30fe80:c25a:0:1d00::/56fe80:c25a:0:1dff:ffff:ffff:ffff:ffff
31fe80:c25a:0:1e00::/56fe80:c25a:0:1eff:ffff:ffff:ffff:ffff
32fe80:c25a:0:1f00::/56fe80:c25a:0:1fff:ffff:ffff:ffff:ffff
33fe80:c25a:0:2000::/56fe80:c25a:0:20ff:ffff:ffff:ffff:ffff
34fe80:c25a:0:2100::/56fe80:c25a:0:21ff:ffff:ffff:ffff:ffff
35fe80:c25a:0:2200::/56fe80:c25a:0:22ff:ffff:ffff:ffff:ffff
36fe80:c25a:0:2300::/56fe80:c25a:0:23ff:ffff:ffff:ffff:ffff
37fe80:c25a:0:2400::/56fe80:c25a:0:24ff:ffff:ffff:ffff:ffff
38fe80:c25a:0:2500::/56fe80:c25a:0:25ff:ffff:ffff:ffff:ffff
39fe80:c25a:0:2600::/56fe80:c25a:0:26ff:ffff:ffff:ffff:ffff
40fe80:c25a:0:2700::/56fe80:c25a:0:27ff:ffff:ffff:ffff:ffff
41fe80:c25a:0:2800::/56fe80:c25a:0:28ff:ffff:ffff:ffff:ffff
42fe80:c25a:0:2900::/56fe80:c25a:0:29ff:ffff:ffff:ffff:ffff
43fe80:c25a:0:2a00::/56fe80:c25a:0:2aff:ffff:ffff:ffff:ffff
44fe80:c25a:0:2b00::/56fe80:c25a:0:2bff:ffff:ffff:ffff:ffff
45fe80:c25a:0:2c00::/56fe80:c25a:0:2cff:ffff:ffff:ffff:ffff
46fe80:c25a:0:2d00::/56fe80:c25a:0:2dff:ffff:ffff:ffff:ffff
47fe80:c25a:0:2e00::/56fe80:c25a:0:2eff:ffff:ffff:ffff:ffff
48fe80:c25a:0:2f00::/56fe80:c25a:0:2fff:ffff:ffff:ffff:ffff
49fe80:c25a:0:3000::/56fe80:c25a:0:30ff:ffff:ffff:ffff:ffff
50fe80:c25a:0:3100::/56fe80:c25a:0:31ff:ffff:ffff:ffff:ffff
51fe80:c25a:0:3200::/56fe80:c25a:0:32ff:ffff:ffff:ffff:ffff
52fe80:c25a:0:3300::/56fe80:c25a:0:33ff:ffff:ffff:ffff:ffff
53fe80:c25a:0:3400::/56fe80:c25a:0:34ff:ffff:ffff:ffff:ffff
54fe80:c25a:0:3500::/56fe80:c25a:0:35ff:ffff:ffff:ffff:ffff
55fe80:c25a:0:3600::/56fe80:c25a:0:36ff:ffff:ffff:ffff:ffff
56fe80:c25a:0:3700::/56fe80:c25a:0:37ff:ffff:ffff:ffff:ffff
57fe80:c25a:0:3800::/56fe80:c25a:0:38ff:ffff:ffff:ffff:ffff
58fe80:c25a:0:3900::/56fe80:c25a:0:39ff:ffff:ffff:ffff:ffff
59fe80:c25a:0:3a00::/56fe80:c25a:0:3aff:ffff:ffff:ffff:ffff
60fe80:c25a:0:3b00::/56fe80:c25a:0:3bff:ffff:ffff:ffff:ffff
61fe80:c25a:0:3c00::/56fe80:c25a:0:3cff:ffff:ffff:ffff:ffff
62fe80:c25a:0:3d00::/56fe80:c25a:0:3dff:ffff:ffff:ffff:ffff
63fe80:c25a:0:3e00::/56fe80:c25a:0:3eff:ffff:ffff:ffff:ffff
64fe80:c25a:0:3f00::/56fe80:c25a:0:3fff:ffff:ffff:ffff:ffff
65fe80:c25a:0:4000::/56fe80:c25a:0:40ff:ffff:ffff:ffff:ffff
66fe80:c25a:0:4100::/56fe80:c25a:0:41ff:ffff:ffff:ffff:ffff
67fe80:c25a:0:4200::/56fe80:c25a:0:42ff:ffff:ffff:ffff:ffff
68fe80:c25a:0:4300::/56fe80:c25a:0:43ff:ffff:ffff:ffff:ffff
69fe80:c25a:0:4400::/56fe80:c25a:0:44ff:ffff:ffff:ffff:ffff
70fe80:c25a:0:4500::/56fe80:c25a:0:45ff:ffff:ffff:ffff:ffff
71fe80:c25a:0:4600::/56fe80:c25a:0:46ff:ffff:ffff:ffff:ffff
72fe80:c25a:0:4700::/56fe80:c25a:0:47ff:ffff:ffff:ffff:ffff
73fe80:c25a:0:4800::/56fe80:c25a:0:48ff:ffff:ffff:ffff:ffff
74fe80:c25a:0:4900::/56fe80:c25a:0:49ff:ffff:ffff:ffff:ffff
75fe80:c25a:0:4a00::/56fe80:c25a:0:4aff:ffff:ffff:ffff:ffff
76fe80:c25a:0:4b00::/56fe80:c25a:0:4bff:ffff:ffff:ffff:ffff
77fe80:c25a:0:4c00::/56fe80:c25a:0:4cff:ffff:ffff:ffff:ffff
78fe80:c25a:0:4d00::/56fe80:c25a:0:4dff:ffff:ffff:ffff:ffff
79fe80:c25a:0:4e00::/56fe80:c25a:0:4eff:ffff:ffff:ffff:ffff
80fe80:c25a:0:4f00::/56fe80:c25a:0:4fff:ffff:ffff:ffff:ffff
81fe80:c25a:0:5000::/56fe80:c25a:0:50ff:ffff:ffff:ffff:ffff
82fe80:c25a:0:5100::/56fe80:c25a:0:51ff:ffff:ffff:ffff:ffff
83fe80:c25a:0:5200::/56fe80:c25a:0:52ff:ffff:ffff:ffff:ffff
84fe80:c25a:0:5300::/56fe80:c25a:0:53ff:ffff:ffff:ffff:ffff
85fe80:c25a:0:5400::/56fe80:c25a:0:54ff:ffff:ffff:ffff:ffff
86fe80:c25a:0:5500::/56fe80:c25a:0:55ff:ffff:ffff:ffff:ffff
87fe80:c25a:0:5600::/56fe80:c25a:0:56ff:ffff:ffff:ffff:ffff
88fe80:c25a:0:5700::/56fe80:c25a:0:57ff:ffff:ffff:ffff:ffff
89fe80:c25a:0:5800::/56fe80:c25a:0:58ff:ffff:ffff:ffff:ffff
90fe80:c25a:0:5900::/56fe80:c25a:0:59ff:ffff:ffff:ffff:ffff
91fe80:c25a:0:5a00::/56fe80:c25a:0:5aff:ffff:ffff:ffff:ffff
92fe80:c25a:0:5b00::/56fe80:c25a:0:5bff:ffff:ffff:ffff:ffff
93fe80:c25a:0:5c00::/56fe80:c25a:0:5cff:ffff:ffff:ffff:ffff
94fe80:c25a:0:5d00::/56fe80:c25a:0:5dff:ffff:ffff:ffff:ffff
95fe80:c25a:0:5e00::/56fe80:c25a:0:5eff:ffff:ffff:ffff:ffff
96fe80:c25a:0:5f00::/56fe80:c25a:0:5fff:ffff:ffff:ffff:ffff
97fe80:c25a:0:6000::/56fe80:c25a:0:60ff:ffff:ffff:ffff:ffff
98fe80:c25a:0:6100::/56fe80:c25a:0:61ff:ffff:ffff:ffff:ffff
99fe80:c25a:0:6200::/56fe80:c25a:0:62ff:ffff:ffff:ffff:ffff
100fe80:c25a:0:6300::/56fe80:c25a:0:63ff:ffff:ffff:ffff:ffff
101fe80:c25a:0:6400::/56fe80:c25a:0:64ff:ffff:ffff:ffff:ffff
102fe80:c25a:0:6500::/56fe80:c25a:0:65ff:ffff:ffff:ffff:ffff
103fe80:c25a:0:6600::/56fe80:c25a:0:66ff:ffff:ffff:ffff:ffff
104fe80:c25a:0:6700::/56fe80:c25a:0:67ff:ffff:ffff:ffff:ffff
105fe80:c25a:0:6800::/56fe80:c25a:0:68ff:ffff:ffff:ffff:ffff
106fe80:c25a:0:6900::/56fe80:c25a:0:69ff:ffff:ffff:ffff:ffff
107fe80:c25a:0:6a00::/56fe80:c25a:0:6aff:ffff:ffff:ffff:ffff
108fe80:c25a:0:6b00::/56fe80:c25a:0:6bff:ffff:ffff:ffff:ffff
109fe80:c25a:0:6c00::/56fe80:c25a:0:6cff:ffff:ffff:ffff:ffff
110fe80:c25a:0:6d00::/56fe80:c25a:0:6dff:ffff:ffff:ffff:ffff
111fe80:c25a:0:6e00::/56fe80:c25a:0:6eff:ffff:ffff:ffff:ffff
112fe80:c25a:0:6f00::/56fe80:c25a:0:6fff:ffff:ffff:ffff:ffff
113fe80:c25a:0:7000::/56fe80:c25a:0:70ff:ffff:ffff:ffff:ffff
114fe80:c25a:0:7100::/56fe80:c25a:0:71ff:ffff:ffff:ffff:ffff
115fe80:c25a:0:7200::/56fe80:c25a:0:72ff:ffff:ffff:ffff:ffff
116fe80:c25a:0:7300::/56fe80:c25a:0:73ff:ffff:ffff:ffff:ffff
117fe80:c25a:0:7400::/56fe80:c25a:0:74ff:ffff:ffff:ffff:ffff
118fe80:c25a:0:7500::/56fe80:c25a:0:75ff:ffff:ffff:ffff:ffff
119fe80:c25a:0:7600::/56fe80:c25a:0:76ff:ffff:ffff:ffff:ffff
120fe80:c25a:0:7700::/56fe80:c25a:0:77ff:ffff:ffff:ffff:ffff
121fe80:c25a:0:7800::/56fe80:c25a:0:78ff:ffff:ffff:ffff:ffff
122fe80:c25a:0:7900::/56fe80:c25a:0:79ff:ffff:ffff:ffff:ffff
123fe80:c25a:0:7a00::/56fe80:c25a:0:7aff:ffff:ffff:ffff:ffff
124fe80:c25a:0:7b00::/56fe80:c25a:0:7bff:ffff:ffff:ffff:ffff
125fe80:c25a:0:7c00::/56fe80:c25a:0:7cff:ffff:ffff:ffff:ffff
126fe80:c25a:0:7d00::/56fe80:c25a:0:7dff:ffff:ffff:ffff:ffff
127fe80:c25a:0:7e00::/56fe80:c25a:0:7eff:ffff:ffff:ffff:ffff
128fe80:c25a:0:7f00::/56fe80:c25a:0:7fff:ffff:ffff:ffff:ffff
129fe80:c25a:0:8000::/56fe80:c25a:0:80ff:ffff:ffff:ffff:ffff
130fe80:c25a:0:8100::/56fe80:c25a:0:81ff:ffff:ffff:ffff:ffff
131fe80:c25a:0:8200::/56fe80:c25a:0:82ff:ffff:ffff:ffff:ffff
132fe80:c25a:0:8300::/56fe80:c25a:0:83ff:ffff:ffff:ffff:ffff
133fe80:c25a:0:8400::/56fe80:c25a:0:84ff:ffff:ffff:ffff:ffff
134fe80:c25a:0:8500::/56fe80:c25a:0:85ff:ffff:ffff:ffff:ffff
135fe80:c25a:0:8600::/56fe80:c25a:0:86ff:ffff:ffff:ffff:ffff
136fe80:c25a:0:8700::/56fe80:c25a:0:87ff:ffff:ffff:ffff:ffff
137fe80:c25a:0:8800::/56fe80:c25a:0:88ff:ffff:ffff:ffff:ffff
138fe80:c25a:0:8900::/56fe80:c25a:0:89ff:ffff:ffff:ffff:ffff
139fe80:c25a:0:8a00::/56fe80:c25a:0:8aff:ffff:ffff:ffff:ffff
140fe80:c25a:0:8b00::/56fe80:c25a:0:8bff:ffff:ffff:ffff:ffff
141fe80:c25a:0:8c00::/56fe80:c25a:0:8cff:ffff:ffff:ffff:ffff
142fe80:c25a:0:8d00::/56fe80:c25a:0:8dff:ffff:ffff:ffff:ffff
143fe80:c25a:0:8e00::/56fe80:c25a:0:8eff:ffff:ffff:ffff:ffff
144fe80:c25a:0:8f00::/56fe80:c25a:0:8fff:ffff:ffff:ffff:ffff
145fe80:c25a:0:9000::/56fe80:c25a:0:90ff:ffff:ffff:ffff:ffff
146fe80:c25a:0:9100::/56fe80:c25a:0:91ff:ffff:ffff:ffff:ffff
147fe80:c25a:0:9200::/56fe80:c25a:0:92ff:ffff:ffff:ffff:ffff
148fe80:c25a:0:9300::/56fe80:c25a:0:93ff:ffff:ffff:ffff:ffff
149fe80:c25a:0:9400::/56fe80:c25a:0:94ff:ffff:ffff:ffff:ffff
150fe80:c25a:0:9500::/56fe80:c25a:0:95ff:ffff:ffff:ffff:ffff
151fe80:c25a:0:9600::/56fe80:c25a:0:96ff:ffff:ffff:ffff:ffff
152fe80:c25a:0:9700::/56fe80:c25a:0:97ff:ffff:ffff:ffff:ffff
153fe80:c25a:0:9800::/56fe80:c25a:0:98ff:ffff:ffff:ffff:ffff
154fe80:c25a:0:9900::/56fe80:c25a:0:99ff:ffff:ffff:ffff:ffff
155fe80:c25a:0:9a00::/56fe80:c25a:0:9aff:ffff:ffff:ffff:ffff
156fe80:c25a:0:9b00::/56fe80:c25a:0:9bff:ffff:ffff:ffff:ffff
157fe80:c25a:0:9c00::/56fe80:c25a:0:9cff:ffff:ffff:ffff:ffff
158fe80:c25a:0:9d00::/56fe80:c25a:0:9dff:ffff:ffff:ffff:ffff
159fe80:c25a:0:9e00::/56fe80:c25a:0:9eff:ffff:ffff:ffff:ffff
160fe80:c25a:0:9f00::/56fe80:c25a:0:9fff:ffff:ffff:ffff:ffff
161fe80:c25a:0:a000::/56fe80:c25a:0:a0ff:ffff:ffff:ffff:ffff
162fe80:c25a:0:a100::/56fe80:c25a:0:a1ff:ffff:ffff:ffff:ffff
163fe80:c25a:0:a200::/56fe80:c25a:0:a2ff:ffff:ffff:ffff:ffff
164fe80:c25a:0:a300::/56fe80:c25a:0:a3ff:ffff:ffff:ffff:ffff
165fe80:c25a:0:a400::/56fe80:c25a:0:a4ff:ffff:ffff:ffff:ffff
166fe80:c25a:0:a500::/56fe80:c25a:0:a5ff:ffff:ffff:ffff:ffff
167fe80:c25a:0:a600::/56fe80:c25a:0:a6ff:ffff:ffff:ffff:ffff
168fe80:c25a:0:a700::/56fe80:c25a:0:a7ff:ffff:ffff:ffff:ffff
169fe80:c25a:0:a800::/56fe80:c25a:0:a8ff:ffff:ffff:ffff:ffff
170fe80:c25a:0:a900::/56fe80:c25a:0:a9ff:ffff:ffff:ffff:ffff
171fe80:c25a:0:aa00::/56fe80:c25a:0:aaff:ffff:ffff:ffff:ffff
172fe80:c25a:0:ab00::/56fe80:c25a:0:abff:ffff:ffff:ffff:ffff
173fe80:c25a:0:ac00::/56fe80:c25a:0:acff:ffff:ffff:ffff:ffff
174fe80:c25a:0:ad00::/56fe80:c25a:0:adff:ffff:ffff:ffff:ffff
175fe80:c25a:0:ae00::/56fe80:c25a:0:aeff:ffff:ffff:ffff:ffff
176fe80:c25a:0:af00::/56fe80:c25a:0:afff:ffff:ffff:ffff:ffff
177fe80:c25a:0:b000::/56fe80:c25a:0:b0ff:ffff:ffff:ffff:ffff
178fe80:c25a:0:b100::/56fe80:c25a:0:b1ff:ffff:ffff:ffff:ffff
179fe80:c25a:0:b200::/56fe80:c25a:0:b2ff:ffff:ffff:ffff:ffff
180fe80:c25a:0:b300::/56fe80:c25a:0:b3ff:ffff:ffff:ffff:ffff
181fe80:c25a:0:b400::/56fe80:c25a:0:b4ff:ffff:ffff:ffff:ffff
182fe80:c25a:0:b500::/56fe80:c25a:0:b5ff:ffff:ffff:ffff:ffff
183fe80:c25a:0:b600::/56fe80:c25a:0:b6ff:ffff:ffff:ffff:ffff
184fe80:c25a:0:b700::/56fe80:c25a:0:b7ff:ffff:ffff:ffff:ffff
185fe80:c25a:0:b800::/56fe80:c25a:0:b8ff:ffff:ffff:ffff:ffff
186fe80:c25a:0:b900::/56fe80:c25a:0:b9ff:ffff:ffff:ffff:ffff
187fe80:c25a:0:ba00::/56fe80:c25a:0:baff:ffff:ffff:ffff:ffff
188fe80:c25a:0:bb00::/56fe80:c25a:0:bbff:ffff:ffff:ffff:ffff
189fe80:c25a:0:bc00::/56fe80:c25a:0:bcff:ffff:ffff:ffff:ffff
190fe80:c25a:0:bd00::/56fe80:c25a:0:bdff:ffff:ffff:ffff:ffff
191fe80:c25a:0:be00::/56fe80:c25a:0:beff:ffff:ffff:ffff:ffff
192fe80:c25a:0:bf00::/56fe80:c25a:0:bfff:ffff:ffff:ffff:ffff
193fe80:c25a:0:c000::/56fe80:c25a:0:c0ff:ffff:ffff:ffff:ffff
194fe80:c25a:0:c100::/56fe80:c25a:0:c1ff:ffff:ffff:ffff:ffff
195fe80:c25a:0:c200::/56fe80:c25a:0:c2ff:ffff:ffff:ffff:ffff
196fe80:c25a:0:c300::/56fe80:c25a:0:c3ff:ffff:ffff:ffff:ffff
197fe80:c25a:0:c400::/56fe80:c25a:0:c4ff:ffff:ffff:ffff:ffff
198fe80:c25a:0:c500::/56fe80:c25a:0:c5ff:ffff:ffff:ffff:ffff
199fe80:c25a:0:c600::/56fe80:c25a:0:c6ff:ffff:ffff:ffff:ffff
200fe80:c25a:0:c700::/56fe80:c25a:0:c7ff:ffff:ffff:ffff:ffff
201fe80:c25a:0:c800::/56fe80:c25a:0:c8ff:ffff:ffff:ffff:ffff
202fe80:c25a:0:c900::/56fe80:c25a:0:c9ff:ffff:ffff:ffff:ffff
203fe80:c25a:0:ca00::/56fe80:c25a:0:caff:ffff:ffff:ffff:ffff
204fe80:c25a:0:cb00::/56fe80:c25a:0:cbff:ffff:ffff:ffff:ffff
205fe80:c25a:0:cc00::/56fe80:c25a:0:ccff:ffff:ffff:ffff:ffff
206fe80:c25a:0:cd00::/56fe80:c25a:0:cdff:ffff:ffff:ffff:ffff
207fe80:c25a:0:ce00::/56fe80:c25a:0:ceff:ffff:ffff:ffff:ffff
208fe80:c25a:0:cf00::/56fe80:c25a:0:cfff:ffff:ffff:ffff:ffff
209fe80:c25a:0:d000::/56fe80:c25a:0:d0ff:ffff:ffff:ffff:ffff
210fe80:c25a:0:d100::/56fe80:c25a:0:d1ff:ffff:ffff:ffff:ffff
211fe80:c25a:0:d200::/56fe80:c25a:0:d2ff:ffff:ffff:ffff:ffff
212fe80:c25a:0:d300::/56fe80:c25a:0:d3ff:ffff:ffff:ffff:ffff
213fe80:c25a:0:d400::/56fe80:c25a:0:d4ff:ffff:ffff:ffff:ffff
214fe80:c25a:0:d500::/56fe80:c25a:0:d5ff:ffff:ffff:ffff:ffff
215fe80:c25a:0:d600::/56fe80:c25a:0:d6ff:ffff:ffff:ffff:ffff
216fe80:c25a:0:d700::/56fe80:c25a:0:d7ff:ffff:ffff:ffff:ffff
217fe80:c25a:0:d800::/56fe80:c25a:0:d8ff:ffff:ffff:ffff:ffff
218fe80:c25a:0:d900::/56fe80:c25a:0:d9ff:ffff:ffff:ffff:ffff
219fe80:c25a:0:da00::/56fe80:c25a:0:daff:ffff:ffff:ffff:ffff
220fe80:c25a:0:db00::/56fe80:c25a:0:dbff:ffff:ffff:ffff:ffff
221fe80:c25a:0:dc00::/56fe80:c25a:0:dcff:ffff:ffff:ffff:ffff
222fe80:c25a:0:dd00::/56fe80:c25a:0:ddff:ffff:ffff:ffff:ffff
223fe80:c25a:0:de00::/56fe80:c25a:0:deff:ffff:ffff:ffff:ffff
224fe80:c25a:0:df00::/56fe80:c25a:0:dfff:ffff:ffff:ffff:ffff
225fe80:c25a:0:e000::/56fe80:c25a:0:e0ff:ffff:ffff:ffff:ffff
226fe80:c25a:0:e100::/56fe80:c25a:0:e1ff:ffff:ffff:ffff:ffff
227fe80:c25a:0:e200::/56fe80:c25a:0:e2ff:ffff:ffff:ffff:ffff
228fe80:c25a:0:e300::/56fe80:c25a:0:e3ff:ffff:ffff:ffff:ffff
229fe80:c25a:0:e400::/56fe80:c25a:0:e4ff:ffff:ffff:ffff:ffff
230fe80:c25a:0:e500::/56fe80:c25a:0:e5ff:ffff:ffff:ffff:ffff
231fe80:c25a:0:e600::/56fe80:c25a:0:e6ff:ffff:ffff:ffff:ffff
232fe80:c25a:0:e700::/56fe80:c25a:0:e7ff:ffff:ffff:ffff:ffff
233fe80:c25a:0:e800::/56fe80:c25a:0:e8ff:ffff:ffff:ffff:ffff
234fe80:c25a:0:e900::/56fe80:c25a:0:e9ff:ffff:ffff:ffff:ffff
235fe80:c25a:0:ea00::/56fe80:c25a:0:eaff:ffff:ffff:ffff:ffff
236fe80:c25a:0:eb00::/56fe80:c25a:0:ebff:ffff:ffff:ffff:ffff
237fe80:c25a:0:ec00::/56fe80:c25a:0:ecff:ffff:ffff:ffff:ffff
238fe80:c25a:0:ed00::/56fe80:c25a:0:edff:ffff:ffff:ffff:ffff
239fe80:c25a:0:ee00::/56fe80:c25a:0:eeff:ffff:ffff:ffff:ffff
240fe80:c25a:0:ef00::/56fe80:c25a:0:efff:ffff:ffff:ffff:ffff
241fe80:c25a:0:f000::/56fe80:c25a:0:f0ff:ffff:ffff:ffff:ffff
242fe80:c25a:0:f100::/56fe80:c25a:0:f1ff:ffff:ffff:ffff:ffff
243fe80:c25a:0:f200::/56fe80:c25a:0:f2ff:ffff:ffff:ffff:ffff
244fe80:c25a:0:f300::/56fe80:c25a:0:f3ff:ffff:ffff:ffff:ffff
245fe80:c25a:0:f400::/56fe80:c25a:0:f4ff:ffff:ffff:ffff:ffff
246fe80:c25a:0:f500::/56fe80:c25a:0:f5ff:ffff:ffff:ffff:ffff
247fe80:c25a:0:f600::/56fe80:c25a:0:f6ff:ffff:ffff:ffff:ffff
248fe80:c25a:0:f700::/56fe80:c25a:0:f7ff:ffff:ffff:ffff:ffff
249fe80:c25a:0:f800::/56fe80:c25a:0:f8ff:ffff:ffff:ffff:ffff
250fe80:c25a:0:f900::/56fe80:c25a:0:f9ff:ffff:ffff:ffff:ffff
251fe80:c25a:0:fa00::/56fe80:c25a:0:faff:ffff:ffff:ffff:ffff
252fe80:c25a:0:fb00::/56fe80:c25a:0:fbff:ffff:ffff:ffff:ffff
253fe80:c25a:0:fc00::/56fe80:c25a:0:fcff:ffff:ffff:ffff:ffff
254fe80:c25a:0:fd00::/56fe80:c25a:0:fdff:ffff:ffff:ffff:ffff
255fe80:c25a:0:fe00::/56fe80:c25a:0:feff:ffff:ffff:ffff:ffff
256fe80:c25a:0:ff00::/56fe80:c25a:0: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.