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/16
Addresses2^112
/64 networks2^48
Network
ffe4::/16
First address
ffe4::
Last address
ffe4:ffff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
5,192,296,858,534,827,628,530,496,329,220,096 (2^112)
/64 networks (LANs)
281,474,976,710,656 (2^48)
Full form
ffe4:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
4.e.f.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ffe4::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1ffe4::/24ffe4:ff:ffff:ffff:ffff:ffff:ffff:ffff
2ffe4:100::/24ffe4:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3ffe4:200::/24ffe4:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4ffe4:300::/24ffe4:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5ffe4:400::/24ffe4:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6ffe4:500::/24ffe4:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7ffe4:600::/24ffe4:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8ffe4:700::/24ffe4:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9ffe4:800::/24ffe4:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10ffe4:900::/24ffe4:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11ffe4:a00::/24ffe4:aff:ffff:ffff:ffff:ffff:ffff:ffff
12ffe4:b00::/24ffe4:bff:ffff:ffff:ffff:ffff:ffff:ffff
13ffe4:c00::/24ffe4:cff:ffff:ffff:ffff:ffff:ffff:ffff
14ffe4:d00::/24ffe4:dff:ffff:ffff:ffff:ffff:ffff:ffff
15ffe4:e00::/24ffe4:eff:ffff:ffff:ffff:ffff:ffff:ffff
16ffe4:f00::/24ffe4:fff:ffff:ffff:ffff:ffff:ffff:ffff
17ffe4:1000::/24ffe4:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18ffe4:1100::/24ffe4:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19ffe4:1200::/24ffe4:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20ffe4:1300::/24ffe4:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21ffe4:1400::/24ffe4:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22ffe4:1500::/24ffe4:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23ffe4:1600::/24ffe4:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24ffe4:1700::/24ffe4:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25ffe4:1800::/24ffe4:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26ffe4:1900::/24ffe4:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27ffe4:1a00::/24ffe4:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28ffe4:1b00::/24ffe4:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29ffe4:1c00::/24ffe4:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30ffe4:1d00::/24ffe4:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31ffe4:1e00::/24ffe4:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32ffe4:1f00::/24ffe4:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33ffe4:2000::/24ffe4:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34ffe4:2100::/24ffe4:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35ffe4:2200::/24ffe4:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36ffe4:2300::/24ffe4:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37ffe4:2400::/24ffe4:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38ffe4:2500::/24ffe4:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39ffe4:2600::/24ffe4:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40ffe4:2700::/24ffe4:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41ffe4:2800::/24ffe4:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42ffe4:2900::/24ffe4:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43ffe4:2a00::/24ffe4:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44ffe4:2b00::/24ffe4:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45ffe4:2c00::/24ffe4:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46ffe4:2d00::/24ffe4:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47ffe4:2e00::/24ffe4:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48ffe4:2f00::/24ffe4:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49ffe4:3000::/24ffe4:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50ffe4:3100::/24ffe4:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51ffe4:3200::/24ffe4:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52ffe4:3300::/24ffe4:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53ffe4:3400::/24ffe4:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54ffe4:3500::/24ffe4:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55ffe4:3600::/24ffe4:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56ffe4:3700::/24ffe4:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57ffe4:3800::/24ffe4:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58ffe4:3900::/24ffe4:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59ffe4:3a00::/24ffe4:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60ffe4:3b00::/24ffe4:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61ffe4:3c00::/24ffe4:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62ffe4:3d00::/24ffe4:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63ffe4:3e00::/24ffe4:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64ffe4:3f00::/24ffe4:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65ffe4:4000::/24ffe4:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66ffe4:4100::/24ffe4:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67ffe4:4200::/24ffe4:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68ffe4:4300::/24ffe4:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69ffe4:4400::/24ffe4:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70ffe4:4500::/24ffe4:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71ffe4:4600::/24ffe4:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72ffe4:4700::/24ffe4:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73ffe4:4800::/24ffe4:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74ffe4:4900::/24ffe4:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75ffe4:4a00::/24ffe4:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76ffe4:4b00::/24ffe4:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77ffe4:4c00::/24ffe4:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78ffe4:4d00::/24ffe4:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79ffe4:4e00::/24ffe4:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80ffe4:4f00::/24ffe4:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81ffe4:5000::/24ffe4:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82ffe4:5100::/24ffe4:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83ffe4:5200::/24ffe4:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84ffe4:5300::/24ffe4:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85ffe4:5400::/24ffe4:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86ffe4:5500::/24ffe4:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87ffe4:5600::/24ffe4:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88ffe4:5700::/24ffe4:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89ffe4:5800::/24ffe4:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90ffe4:5900::/24ffe4:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91ffe4:5a00::/24ffe4:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92ffe4:5b00::/24ffe4:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93ffe4:5c00::/24ffe4:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94ffe4:5d00::/24ffe4:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95ffe4:5e00::/24ffe4:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96ffe4:5f00::/24ffe4:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97ffe4:6000::/24ffe4:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98ffe4:6100::/24ffe4:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99ffe4:6200::/24ffe4:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100ffe4:6300::/24ffe4:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101ffe4:6400::/24ffe4:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102ffe4:6500::/24ffe4:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103ffe4:6600::/24ffe4:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104ffe4:6700::/24ffe4:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105ffe4:6800::/24ffe4:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106ffe4:6900::/24ffe4:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107ffe4:6a00::/24ffe4:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108ffe4:6b00::/24ffe4:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109ffe4:6c00::/24ffe4:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110ffe4:6d00::/24ffe4:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111ffe4:6e00::/24ffe4:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112ffe4:6f00::/24ffe4:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113ffe4:7000::/24ffe4:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114ffe4:7100::/24ffe4:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115ffe4:7200::/24ffe4:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116ffe4:7300::/24ffe4:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117ffe4:7400::/24ffe4:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118ffe4:7500::/24ffe4:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119ffe4:7600::/24ffe4:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120ffe4:7700::/24ffe4:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121ffe4:7800::/24ffe4:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122ffe4:7900::/24ffe4:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123ffe4:7a00::/24ffe4:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124ffe4:7b00::/24ffe4:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125ffe4:7c00::/24ffe4:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126ffe4:7d00::/24ffe4:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127ffe4:7e00::/24ffe4:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128ffe4:7f00::/24ffe4:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129ffe4:8000::/24ffe4:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130ffe4:8100::/24ffe4:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131ffe4:8200::/24ffe4:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132ffe4:8300::/24ffe4:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133ffe4:8400::/24ffe4:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134ffe4:8500::/24ffe4:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135ffe4:8600::/24ffe4:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136ffe4:8700::/24ffe4:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137ffe4:8800::/24ffe4:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138ffe4:8900::/24ffe4:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139ffe4:8a00::/24ffe4:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140ffe4:8b00::/24ffe4:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141ffe4:8c00::/24ffe4:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142ffe4:8d00::/24ffe4:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143ffe4:8e00::/24ffe4:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144ffe4:8f00::/24ffe4:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145ffe4:9000::/24ffe4:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146ffe4:9100::/24ffe4:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147ffe4:9200::/24ffe4:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148ffe4:9300::/24ffe4:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149ffe4:9400::/24ffe4:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150ffe4:9500::/24ffe4:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151ffe4:9600::/24ffe4:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152ffe4:9700::/24ffe4:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153ffe4:9800::/24ffe4:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154ffe4:9900::/24ffe4:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155ffe4:9a00::/24ffe4:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156ffe4:9b00::/24ffe4:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157ffe4:9c00::/24ffe4:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158ffe4:9d00::/24ffe4:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159ffe4:9e00::/24ffe4:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160ffe4:9f00::/24ffe4:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161ffe4:a000::/24ffe4:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162ffe4:a100::/24ffe4:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163ffe4:a200::/24ffe4:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164ffe4:a300::/24ffe4:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165ffe4:a400::/24ffe4:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166ffe4:a500::/24ffe4:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167ffe4:a600::/24ffe4:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168ffe4:a700::/24ffe4:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169ffe4:a800::/24ffe4:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170ffe4:a900::/24ffe4:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171ffe4:aa00::/24ffe4:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172ffe4:ab00::/24ffe4:abff:ffff:ffff:ffff:ffff:ffff:ffff
173ffe4:ac00::/24ffe4:acff:ffff:ffff:ffff:ffff:ffff:ffff
174ffe4:ad00::/24ffe4:adff:ffff:ffff:ffff:ffff:ffff:ffff
175ffe4:ae00::/24ffe4:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176ffe4:af00::/24ffe4:afff:ffff:ffff:ffff:ffff:ffff:ffff
177ffe4:b000::/24ffe4:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178ffe4:b100::/24ffe4:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179ffe4:b200::/24ffe4:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180ffe4:b300::/24ffe4:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181ffe4:b400::/24ffe4:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182ffe4:b500::/24ffe4:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183ffe4:b600::/24ffe4:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184ffe4:b700::/24ffe4:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185ffe4:b800::/24ffe4:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186ffe4:b900::/24ffe4:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187ffe4:ba00::/24ffe4:baff:ffff:ffff:ffff:ffff:ffff:ffff
188ffe4:bb00::/24ffe4:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189ffe4:bc00::/24ffe4:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190ffe4:bd00::/24ffe4:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191ffe4:be00::/24ffe4:beff:ffff:ffff:ffff:ffff:ffff:ffff
192ffe4:bf00::/24ffe4:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193ffe4:c000::/24ffe4:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194ffe4:c100::/24ffe4:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195ffe4:c200::/24ffe4:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196ffe4:c300::/24ffe4:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197ffe4:c400::/24ffe4:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198ffe4:c500::/24ffe4:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199ffe4:c600::/24ffe4:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200ffe4:c700::/24ffe4:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201ffe4:c800::/24ffe4:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202ffe4:c900::/24ffe4:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203ffe4:ca00::/24ffe4:caff:ffff:ffff:ffff:ffff:ffff:ffff
204ffe4:cb00::/24ffe4:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205ffe4:cc00::/24ffe4:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206ffe4:cd00::/24ffe4:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207ffe4:ce00::/24ffe4:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208ffe4:cf00::/24ffe4:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209ffe4:d000::/24ffe4:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210ffe4:d100::/24ffe4:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211ffe4:d200::/24ffe4:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212ffe4:d300::/24ffe4:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213ffe4:d400::/24ffe4:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214ffe4:d500::/24ffe4:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215ffe4:d600::/24ffe4:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216ffe4:d700::/24ffe4:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217ffe4:d800::/24ffe4:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218ffe4:d900::/24ffe4:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219ffe4:da00::/24ffe4:daff:ffff:ffff:ffff:ffff:ffff:ffff
220ffe4:db00::/24ffe4:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221ffe4:dc00::/24ffe4:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222ffe4:dd00::/24ffe4:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223ffe4:de00::/24ffe4:deff:ffff:ffff:ffff:ffff:ffff:ffff
224ffe4:df00::/24ffe4:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225ffe4:e000::/24ffe4:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226ffe4:e100::/24ffe4:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227ffe4:e200::/24ffe4:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228ffe4:e300::/24ffe4:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229ffe4:e400::/24ffe4:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230ffe4:e500::/24ffe4:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231ffe4:e600::/24ffe4:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232ffe4:e700::/24ffe4:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233ffe4:e800::/24ffe4:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234ffe4:e900::/24ffe4:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235ffe4:ea00::/24ffe4:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236ffe4:eb00::/24ffe4:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237ffe4:ec00::/24ffe4:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238ffe4:ed00::/24ffe4:edff:ffff:ffff:ffff:ffff:ffff:ffff
239ffe4:ee00::/24ffe4:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240ffe4:ef00::/24ffe4:efff:ffff:ffff:ffff:ffff:ffff:ffff
241ffe4:f000::/24ffe4:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242ffe4:f100::/24ffe4:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243ffe4:f200::/24ffe4:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244ffe4:f300::/24ffe4:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245ffe4:f400::/24ffe4:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246ffe4:f500::/24ffe4:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247ffe4:f600::/24ffe4:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248ffe4:f700::/24ffe4:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249ffe4:f800::/24ffe4:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250ffe4:f900::/24ffe4:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251ffe4:fa00::/24ffe4:faff:ffff:ffff:ffff:ffff:ffff:ffff
252ffe4:fb00::/24ffe4:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253ffe4:fc00::/24ffe4:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254ffe4:fd00::/24ffe4:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255ffe4:fe00::/24ffe4:feff:ffff:ffff:ffff:ffff:ffff:ffff
256ffe4:ff00::/24ffe4:ffff:ffff:ffff:ffff:ffff:ffff:ffff

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.