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
fc3e::/16
First address
fc3e::
Last address
fc3e: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
fc3e:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
e.3.c.f.ip6.arpa
Split into smaller subnets/24
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

fc3e::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fc3e::/24fc3e:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fc3e:100::/24fc3e:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fc3e:200::/24fc3e:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fc3e:300::/24fc3e:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fc3e:400::/24fc3e:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fc3e:500::/24fc3e:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fc3e:600::/24fc3e:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fc3e:700::/24fc3e:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fc3e:800::/24fc3e:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fc3e:900::/24fc3e:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fc3e:a00::/24fc3e:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fc3e:b00::/24fc3e:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fc3e:c00::/24fc3e:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fc3e:d00::/24fc3e:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fc3e:e00::/24fc3e:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fc3e:f00::/24fc3e:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fc3e:1000::/24fc3e:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fc3e:1100::/24fc3e:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fc3e:1200::/24fc3e:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fc3e:1300::/24fc3e:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fc3e:1400::/24fc3e:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fc3e:1500::/24fc3e:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fc3e:1600::/24fc3e:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fc3e:1700::/24fc3e:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fc3e:1800::/24fc3e:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fc3e:1900::/24fc3e:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fc3e:1a00::/24fc3e:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fc3e:1b00::/24fc3e:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fc3e:1c00::/24fc3e:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fc3e:1d00::/24fc3e:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fc3e:1e00::/24fc3e:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fc3e:1f00::/24fc3e:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc3e:2000::/24fc3e:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fc3e:2100::/24fc3e:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fc3e:2200::/24fc3e:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fc3e:2300::/24fc3e:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fc3e:2400::/24fc3e:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fc3e:2500::/24fc3e:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fc3e:2600::/24fc3e:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fc3e:2700::/24fc3e:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fc3e:2800::/24fc3e:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fc3e:2900::/24fc3e:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fc3e:2a00::/24fc3e:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fc3e:2b00::/24fc3e:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fc3e:2c00::/24fc3e:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fc3e:2d00::/24fc3e:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fc3e:2e00::/24fc3e:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fc3e:2f00::/24fc3e:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fc3e:3000::/24fc3e:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fc3e:3100::/24fc3e:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fc3e:3200::/24fc3e:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fc3e:3300::/24fc3e:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fc3e:3400::/24fc3e:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fc3e:3500::/24fc3e:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fc3e:3600::/24fc3e:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fc3e:3700::/24fc3e:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fc3e:3800::/24fc3e:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fc3e:3900::/24fc3e:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fc3e:3a00::/24fc3e:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fc3e:3b00::/24fc3e:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fc3e:3c00::/24fc3e:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fc3e:3d00::/24fc3e:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fc3e:3e00::/24fc3e:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fc3e:3f00::/24fc3e:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fc3e:4000::/24fc3e:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fc3e:4100::/24fc3e:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fc3e:4200::/24fc3e:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fc3e:4300::/24fc3e:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fc3e:4400::/24fc3e:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fc3e:4500::/24fc3e:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fc3e:4600::/24fc3e:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fc3e:4700::/24fc3e:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fc3e:4800::/24fc3e:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fc3e:4900::/24fc3e:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fc3e:4a00::/24fc3e:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fc3e:4b00::/24fc3e:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fc3e:4c00::/24fc3e:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fc3e:4d00::/24fc3e:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fc3e:4e00::/24fc3e:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fc3e:4f00::/24fc3e:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fc3e:5000::/24fc3e:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fc3e:5100::/24fc3e:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fc3e:5200::/24fc3e:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fc3e:5300::/24fc3e:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fc3e:5400::/24fc3e:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fc3e:5500::/24fc3e:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fc3e:5600::/24fc3e:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fc3e:5700::/24fc3e:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fc3e:5800::/24fc3e:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fc3e:5900::/24fc3e:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fc3e:5a00::/24fc3e:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fc3e:5b00::/24fc3e:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fc3e:5c00::/24fc3e:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fc3e:5d00::/24fc3e:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fc3e:5e00::/24fc3e:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fc3e:5f00::/24fc3e:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fc3e:6000::/24fc3e:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fc3e:6100::/24fc3e:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fc3e:6200::/24fc3e:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fc3e:6300::/24fc3e:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fc3e:6400::/24fc3e:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fc3e:6500::/24fc3e:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fc3e:6600::/24fc3e:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fc3e:6700::/24fc3e:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fc3e:6800::/24fc3e:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fc3e:6900::/24fc3e:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fc3e:6a00::/24fc3e:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fc3e:6b00::/24fc3e:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fc3e:6c00::/24fc3e:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fc3e:6d00::/24fc3e:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fc3e:6e00::/24fc3e:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fc3e:6f00::/24fc3e:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc3e:7000::/24fc3e:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fc3e:7100::/24fc3e:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fc3e:7200::/24fc3e:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fc3e:7300::/24fc3e:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fc3e:7400::/24fc3e:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fc3e:7500::/24fc3e:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fc3e:7600::/24fc3e:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fc3e:7700::/24fc3e:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fc3e:7800::/24fc3e:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fc3e:7900::/24fc3e:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fc3e:7a00::/24fc3e:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fc3e:7b00::/24fc3e:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fc3e:7c00::/24fc3e:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fc3e:7d00::/24fc3e:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fc3e:7e00::/24fc3e:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fc3e:7f00::/24fc3e:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fc3e:8000::/24fc3e:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fc3e:8100::/24fc3e:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fc3e:8200::/24fc3e:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fc3e:8300::/24fc3e:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fc3e:8400::/24fc3e:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fc3e:8500::/24fc3e:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fc3e:8600::/24fc3e:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fc3e:8700::/24fc3e:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fc3e:8800::/24fc3e:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fc3e:8900::/24fc3e:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fc3e:8a00::/24fc3e:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fc3e:8b00::/24fc3e:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fc3e:8c00::/24fc3e:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fc3e:8d00::/24fc3e:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fc3e:8e00::/24fc3e:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fc3e:8f00::/24fc3e:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fc3e:9000::/24fc3e:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fc3e:9100::/24fc3e:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fc3e:9200::/24fc3e:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fc3e:9300::/24fc3e:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fc3e:9400::/24fc3e:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fc3e:9500::/24fc3e:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fc3e:9600::/24fc3e:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fc3e:9700::/24fc3e:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fc3e:9800::/24fc3e:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fc3e:9900::/24fc3e:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fc3e:9a00::/24fc3e:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fc3e:9b00::/24fc3e:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fc3e:9c00::/24fc3e:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fc3e:9d00::/24fc3e:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fc3e:9e00::/24fc3e:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fc3e:9f00::/24fc3e:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fc3e:a000::/24fc3e:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fc3e:a100::/24fc3e:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fc3e:a200::/24fc3e:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fc3e:a300::/24fc3e:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fc3e:a400::/24fc3e:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fc3e:a500::/24fc3e:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fc3e:a600::/24fc3e:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fc3e:a700::/24fc3e:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fc3e:a800::/24fc3e:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fc3e:a900::/24fc3e:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fc3e:aa00::/24fc3e:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fc3e:ab00::/24fc3e:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fc3e:ac00::/24fc3e:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fc3e:ad00::/24fc3e:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fc3e:ae00::/24fc3e:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fc3e:af00::/24fc3e:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fc3e:b000::/24fc3e:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fc3e:b100::/24fc3e:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fc3e:b200::/24fc3e:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fc3e:b300::/24fc3e:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fc3e:b400::/24fc3e:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fc3e:b500::/24fc3e:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fc3e:b600::/24fc3e:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fc3e:b700::/24fc3e:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fc3e:b800::/24fc3e:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fc3e:b900::/24fc3e:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fc3e:ba00::/24fc3e:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fc3e:bb00::/24fc3e:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fc3e:bc00::/24fc3e:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fc3e:bd00::/24fc3e:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fc3e:be00::/24fc3e:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fc3e:bf00::/24fc3e:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fc3e:c000::/24fc3e:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fc3e:c100::/24fc3e:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fc3e:c200::/24fc3e:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fc3e:c300::/24fc3e:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fc3e:c400::/24fc3e:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fc3e:c500::/24fc3e:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fc3e:c600::/24fc3e:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fc3e:c700::/24fc3e:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fc3e:c800::/24fc3e:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fc3e:c900::/24fc3e:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fc3e:ca00::/24fc3e:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fc3e:cb00::/24fc3e:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fc3e:cc00::/24fc3e:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fc3e:cd00::/24fc3e:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fc3e:ce00::/24fc3e:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fc3e:cf00::/24fc3e:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fc3e:d000::/24fc3e:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fc3e:d100::/24fc3e:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fc3e:d200::/24fc3e:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fc3e:d300::/24fc3e:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fc3e:d400::/24fc3e:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fc3e:d500::/24fc3e:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fc3e:d600::/24fc3e:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fc3e:d700::/24fc3e:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fc3e:d800::/24fc3e:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fc3e:d900::/24fc3e:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fc3e:da00::/24fc3e:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fc3e:db00::/24fc3e:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fc3e:dc00::/24fc3e:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fc3e:dd00::/24fc3e:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fc3e:de00::/24fc3e:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fc3e:df00::/24fc3e:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fc3e:e000::/24fc3e:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fc3e:e100::/24fc3e:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fc3e:e200::/24fc3e:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fc3e:e300::/24fc3e:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fc3e:e400::/24fc3e:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fc3e:e500::/24fc3e:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fc3e:e600::/24fc3e:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fc3e:e700::/24fc3e:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fc3e:e800::/24fc3e:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fc3e:e900::/24fc3e:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fc3e:ea00::/24fc3e:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fc3e:eb00::/24fc3e:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fc3e:ec00::/24fc3e:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fc3e:ed00::/24fc3e:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fc3e:ee00::/24fc3e:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fc3e:ef00::/24fc3e:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fc3e:f000::/24fc3e:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fc3e:f100::/24fc3e:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fc3e:f200::/24fc3e:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fc3e:f300::/24fc3e:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fc3e:f400::/24fc3e:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fc3e:f500::/24fc3e:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fc3e:f600::/24fc3e:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fc3e:f700::/24fc3e:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fc3e:f800::/24fc3e:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fc3e:f900::/24fc3e:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fc3e:fa00::/24fc3e:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fc3e:fb00::/24fc3e:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fc3e:fc00::/24fc3e:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fc3e:fd00::/24fc3e:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fc3e:fe00::/24fc3e:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fc3e:ff00::/24fc3e: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.