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
fc6d::/16
First address
fc6d::
Last address
fc6d: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
fc6d:0000:0000:0000:0000:0000:0000:0000
Type
Unique local (ULA) fc00::/7
Private IPv6, like RFC 1918; usually fd00::/8
Reverse DNS zone
d.6.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)

fc6d::/16 makes 256 subnets of /24.

Subnets
#SubnetLast address
1fc6d::/24fc6d:ff:ffff:ffff:ffff:ffff:ffff:ffff
2fc6d:100::/24fc6d:1ff:ffff:ffff:ffff:ffff:ffff:ffff
3fc6d:200::/24fc6d:2ff:ffff:ffff:ffff:ffff:ffff:ffff
4fc6d:300::/24fc6d:3ff:ffff:ffff:ffff:ffff:ffff:ffff
5fc6d:400::/24fc6d:4ff:ffff:ffff:ffff:ffff:ffff:ffff
6fc6d:500::/24fc6d:5ff:ffff:ffff:ffff:ffff:ffff:ffff
7fc6d:600::/24fc6d:6ff:ffff:ffff:ffff:ffff:ffff:ffff
8fc6d:700::/24fc6d:7ff:ffff:ffff:ffff:ffff:ffff:ffff
9fc6d:800::/24fc6d:8ff:ffff:ffff:ffff:ffff:ffff:ffff
10fc6d:900::/24fc6d:9ff:ffff:ffff:ffff:ffff:ffff:ffff
11fc6d:a00::/24fc6d:aff:ffff:ffff:ffff:ffff:ffff:ffff
12fc6d:b00::/24fc6d:bff:ffff:ffff:ffff:ffff:ffff:ffff
13fc6d:c00::/24fc6d:cff:ffff:ffff:ffff:ffff:ffff:ffff
14fc6d:d00::/24fc6d:dff:ffff:ffff:ffff:ffff:ffff:ffff
15fc6d:e00::/24fc6d:eff:ffff:ffff:ffff:ffff:ffff:ffff
16fc6d:f00::/24fc6d:fff:ffff:ffff:ffff:ffff:ffff:ffff
17fc6d:1000::/24fc6d:10ff:ffff:ffff:ffff:ffff:ffff:ffff
18fc6d:1100::/24fc6d:11ff:ffff:ffff:ffff:ffff:ffff:ffff
19fc6d:1200::/24fc6d:12ff:ffff:ffff:ffff:ffff:ffff:ffff
20fc6d:1300::/24fc6d:13ff:ffff:ffff:ffff:ffff:ffff:ffff
21fc6d:1400::/24fc6d:14ff:ffff:ffff:ffff:ffff:ffff:ffff
22fc6d:1500::/24fc6d:15ff:ffff:ffff:ffff:ffff:ffff:ffff
23fc6d:1600::/24fc6d:16ff:ffff:ffff:ffff:ffff:ffff:ffff
24fc6d:1700::/24fc6d:17ff:ffff:ffff:ffff:ffff:ffff:ffff
25fc6d:1800::/24fc6d:18ff:ffff:ffff:ffff:ffff:ffff:ffff
26fc6d:1900::/24fc6d:19ff:ffff:ffff:ffff:ffff:ffff:ffff
27fc6d:1a00::/24fc6d:1aff:ffff:ffff:ffff:ffff:ffff:ffff
28fc6d:1b00::/24fc6d:1bff:ffff:ffff:ffff:ffff:ffff:ffff
29fc6d:1c00::/24fc6d:1cff:ffff:ffff:ffff:ffff:ffff:ffff
30fc6d:1d00::/24fc6d:1dff:ffff:ffff:ffff:ffff:ffff:ffff
31fc6d:1e00::/24fc6d:1eff:ffff:ffff:ffff:ffff:ffff:ffff
32fc6d:1f00::/24fc6d:1fff:ffff:ffff:ffff:ffff:ffff:ffff
33fc6d:2000::/24fc6d:20ff:ffff:ffff:ffff:ffff:ffff:ffff
34fc6d:2100::/24fc6d:21ff:ffff:ffff:ffff:ffff:ffff:ffff
35fc6d:2200::/24fc6d:22ff:ffff:ffff:ffff:ffff:ffff:ffff
36fc6d:2300::/24fc6d:23ff:ffff:ffff:ffff:ffff:ffff:ffff
37fc6d:2400::/24fc6d:24ff:ffff:ffff:ffff:ffff:ffff:ffff
38fc6d:2500::/24fc6d:25ff:ffff:ffff:ffff:ffff:ffff:ffff
39fc6d:2600::/24fc6d:26ff:ffff:ffff:ffff:ffff:ffff:ffff
40fc6d:2700::/24fc6d:27ff:ffff:ffff:ffff:ffff:ffff:ffff
41fc6d:2800::/24fc6d:28ff:ffff:ffff:ffff:ffff:ffff:ffff
42fc6d:2900::/24fc6d:29ff:ffff:ffff:ffff:ffff:ffff:ffff
43fc6d:2a00::/24fc6d:2aff:ffff:ffff:ffff:ffff:ffff:ffff
44fc6d:2b00::/24fc6d:2bff:ffff:ffff:ffff:ffff:ffff:ffff
45fc6d:2c00::/24fc6d:2cff:ffff:ffff:ffff:ffff:ffff:ffff
46fc6d:2d00::/24fc6d:2dff:ffff:ffff:ffff:ffff:ffff:ffff
47fc6d:2e00::/24fc6d:2eff:ffff:ffff:ffff:ffff:ffff:ffff
48fc6d:2f00::/24fc6d:2fff:ffff:ffff:ffff:ffff:ffff:ffff
49fc6d:3000::/24fc6d:30ff:ffff:ffff:ffff:ffff:ffff:ffff
50fc6d:3100::/24fc6d:31ff:ffff:ffff:ffff:ffff:ffff:ffff
51fc6d:3200::/24fc6d:32ff:ffff:ffff:ffff:ffff:ffff:ffff
52fc6d:3300::/24fc6d:33ff:ffff:ffff:ffff:ffff:ffff:ffff
53fc6d:3400::/24fc6d:34ff:ffff:ffff:ffff:ffff:ffff:ffff
54fc6d:3500::/24fc6d:35ff:ffff:ffff:ffff:ffff:ffff:ffff
55fc6d:3600::/24fc6d:36ff:ffff:ffff:ffff:ffff:ffff:ffff
56fc6d:3700::/24fc6d:37ff:ffff:ffff:ffff:ffff:ffff:ffff
57fc6d:3800::/24fc6d:38ff:ffff:ffff:ffff:ffff:ffff:ffff
58fc6d:3900::/24fc6d:39ff:ffff:ffff:ffff:ffff:ffff:ffff
59fc6d:3a00::/24fc6d:3aff:ffff:ffff:ffff:ffff:ffff:ffff
60fc6d:3b00::/24fc6d:3bff:ffff:ffff:ffff:ffff:ffff:ffff
61fc6d:3c00::/24fc6d:3cff:ffff:ffff:ffff:ffff:ffff:ffff
62fc6d:3d00::/24fc6d:3dff:ffff:ffff:ffff:ffff:ffff:ffff
63fc6d:3e00::/24fc6d:3eff:ffff:ffff:ffff:ffff:ffff:ffff
64fc6d:3f00::/24fc6d:3fff:ffff:ffff:ffff:ffff:ffff:ffff
65fc6d:4000::/24fc6d:40ff:ffff:ffff:ffff:ffff:ffff:ffff
66fc6d:4100::/24fc6d:41ff:ffff:ffff:ffff:ffff:ffff:ffff
67fc6d:4200::/24fc6d:42ff:ffff:ffff:ffff:ffff:ffff:ffff
68fc6d:4300::/24fc6d:43ff:ffff:ffff:ffff:ffff:ffff:ffff
69fc6d:4400::/24fc6d:44ff:ffff:ffff:ffff:ffff:ffff:ffff
70fc6d:4500::/24fc6d:45ff:ffff:ffff:ffff:ffff:ffff:ffff
71fc6d:4600::/24fc6d:46ff:ffff:ffff:ffff:ffff:ffff:ffff
72fc6d:4700::/24fc6d:47ff:ffff:ffff:ffff:ffff:ffff:ffff
73fc6d:4800::/24fc6d:48ff:ffff:ffff:ffff:ffff:ffff:ffff
74fc6d:4900::/24fc6d:49ff:ffff:ffff:ffff:ffff:ffff:ffff
75fc6d:4a00::/24fc6d:4aff:ffff:ffff:ffff:ffff:ffff:ffff
76fc6d:4b00::/24fc6d:4bff:ffff:ffff:ffff:ffff:ffff:ffff
77fc6d:4c00::/24fc6d:4cff:ffff:ffff:ffff:ffff:ffff:ffff
78fc6d:4d00::/24fc6d:4dff:ffff:ffff:ffff:ffff:ffff:ffff
79fc6d:4e00::/24fc6d:4eff:ffff:ffff:ffff:ffff:ffff:ffff
80fc6d:4f00::/24fc6d:4fff:ffff:ffff:ffff:ffff:ffff:ffff
81fc6d:5000::/24fc6d:50ff:ffff:ffff:ffff:ffff:ffff:ffff
82fc6d:5100::/24fc6d:51ff:ffff:ffff:ffff:ffff:ffff:ffff
83fc6d:5200::/24fc6d:52ff:ffff:ffff:ffff:ffff:ffff:ffff
84fc6d:5300::/24fc6d:53ff:ffff:ffff:ffff:ffff:ffff:ffff
85fc6d:5400::/24fc6d:54ff:ffff:ffff:ffff:ffff:ffff:ffff
86fc6d:5500::/24fc6d:55ff:ffff:ffff:ffff:ffff:ffff:ffff
87fc6d:5600::/24fc6d:56ff:ffff:ffff:ffff:ffff:ffff:ffff
88fc6d:5700::/24fc6d:57ff:ffff:ffff:ffff:ffff:ffff:ffff
89fc6d:5800::/24fc6d:58ff:ffff:ffff:ffff:ffff:ffff:ffff
90fc6d:5900::/24fc6d:59ff:ffff:ffff:ffff:ffff:ffff:ffff
91fc6d:5a00::/24fc6d:5aff:ffff:ffff:ffff:ffff:ffff:ffff
92fc6d:5b00::/24fc6d:5bff:ffff:ffff:ffff:ffff:ffff:ffff
93fc6d:5c00::/24fc6d:5cff:ffff:ffff:ffff:ffff:ffff:ffff
94fc6d:5d00::/24fc6d:5dff:ffff:ffff:ffff:ffff:ffff:ffff
95fc6d:5e00::/24fc6d:5eff:ffff:ffff:ffff:ffff:ffff:ffff
96fc6d:5f00::/24fc6d:5fff:ffff:ffff:ffff:ffff:ffff:ffff
97fc6d:6000::/24fc6d:60ff:ffff:ffff:ffff:ffff:ffff:ffff
98fc6d:6100::/24fc6d:61ff:ffff:ffff:ffff:ffff:ffff:ffff
99fc6d:6200::/24fc6d:62ff:ffff:ffff:ffff:ffff:ffff:ffff
100fc6d:6300::/24fc6d:63ff:ffff:ffff:ffff:ffff:ffff:ffff
101fc6d:6400::/24fc6d:64ff:ffff:ffff:ffff:ffff:ffff:ffff
102fc6d:6500::/24fc6d:65ff:ffff:ffff:ffff:ffff:ffff:ffff
103fc6d:6600::/24fc6d:66ff:ffff:ffff:ffff:ffff:ffff:ffff
104fc6d:6700::/24fc6d:67ff:ffff:ffff:ffff:ffff:ffff:ffff
105fc6d:6800::/24fc6d:68ff:ffff:ffff:ffff:ffff:ffff:ffff
106fc6d:6900::/24fc6d:69ff:ffff:ffff:ffff:ffff:ffff:ffff
107fc6d:6a00::/24fc6d:6aff:ffff:ffff:ffff:ffff:ffff:ffff
108fc6d:6b00::/24fc6d:6bff:ffff:ffff:ffff:ffff:ffff:ffff
109fc6d:6c00::/24fc6d:6cff:ffff:ffff:ffff:ffff:ffff:ffff
110fc6d:6d00::/24fc6d:6dff:ffff:ffff:ffff:ffff:ffff:ffff
111fc6d:6e00::/24fc6d:6eff:ffff:ffff:ffff:ffff:ffff:ffff
112fc6d:6f00::/24fc6d:6fff:ffff:ffff:ffff:ffff:ffff:ffff
113fc6d:7000::/24fc6d:70ff:ffff:ffff:ffff:ffff:ffff:ffff
114fc6d:7100::/24fc6d:71ff:ffff:ffff:ffff:ffff:ffff:ffff
115fc6d:7200::/24fc6d:72ff:ffff:ffff:ffff:ffff:ffff:ffff
116fc6d:7300::/24fc6d:73ff:ffff:ffff:ffff:ffff:ffff:ffff
117fc6d:7400::/24fc6d:74ff:ffff:ffff:ffff:ffff:ffff:ffff
118fc6d:7500::/24fc6d:75ff:ffff:ffff:ffff:ffff:ffff:ffff
119fc6d:7600::/24fc6d:76ff:ffff:ffff:ffff:ffff:ffff:ffff
120fc6d:7700::/24fc6d:77ff:ffff:ffff:ffff:ffff:ffff:ffff
121fc6d:7800::/24fc6d:78ff:ffff:ffff:ffff:ffff:ffff:ffff
122fc6d:7900::/24fc6d:79ff:ffff:ffff:ffff:ffff:ffff:ffff
123fc6d:7a00::/24fc6d:7aff:ffff:ffff:ffff:ffff:ffff:ffff
124fc6d:7b00::/24fc6d:7bff:ffff:ffff:ffff:ffff:ffff:ffff
125fc6d:7c00::/24fc6d:7cff:ffff:ffff:ffff:ffff:ffff:ffff
126fc6d:7d00::/24fc6d:7dff:ffff:ffff:ffff:ffff:ffff:ffff
127fc6d:7e00::/24fc6d:7eff:ffff:ffff:ffff:ffff:ffff:ffff
128fc6d:7f00::/24fc6d:7fff:ffff:ffff:ffff:ffff:ffff:ffff
129fc6d:8000::/24fc6d:80ff:ffff:ffff:ffff:ffff:ffff:ffff
130fc6d:8100::/24fc6d:81ff:ffff:ffff:ffff:ffff:ffff:ffff
131fc6d:8200::/24fc6d:82ff:ffff:ffff:ffff:ffff:ffff:ffff
132fc6d:8300::/24fc6d:83ff:ffff:ffff:ffff:ffff:ffff:ffff
133fc6d:8400::/24fc6d:84ff:ffff:ffff:ffff:ffff:ffff:ffff
134fc6d:8500::/24fc6d:85ff:ffff:ffff:ffff:ffff:ffff:ffff
135fc6d:8600::/24fc6d:86ff:ffff:ffff:ffff:ffff:ffff:ffff
136fc6d:8700::/24fc6d:87ff:ffff:ffff:ffff:ffff:ffff:ffff
137fc6d:8800::/24fc6d:88ff:ffff:ffff:ffff:ffff:ffff:ffff
138fc6d:8900::/24fc6d:89ff:ffff:ffff:ffff:ffff:ffff:ffff
139fc6d:8a00::/24fc6d:8aff:ffff:ffff:ffff:ffff:ffff:ffff
140fc6d:8b00::/24fc6d:8bff:ffff:ffff:ffff:ffff:ffff:ffff
141fc6d:8c00::/24fc6d:8cff:ffff:ffff:ffff:ffff:ffff:ffff
142fc6d:8d00::/24fc6d:8dff:ffff:ffff:ffff:ffff:ffff:ffff
143fc6d:8e00::/24fc6d:8eff:ffff:ffff:ffff:ffff:ffff:ffff
144fc6d:8f00::/24fc6d:8fff:ffff:ffff:ffff:ffff:ffff:ffff
145fc6d:9000::/24fc6d:90ff:ffff:ffff:ffff:ffff:ffff:ffff
146fc6d:9100::/24fc6d:91ff:ffff:ffff:ffff:ffff:ffff:ffff
147fc6d:9200::/24fc6d:92ff:ffff:ffff:ffff:ffff:ffff:ffff
148fc6d:9300::/24fc6d:93ff:ffff:ffff:ffff:ffff:ffff:ffff
149fc6d:9400::/24fc6d:94ff:ffff:ffff:ffff:ffff:ffff:ffff
150fc6d:9500::/24fc6d:95ff:ffff:ffff:ffff:ffff:ffff:ffff
151fc6d:9600::/24fc6d:96ff:ffff:ffff:ffff:ffff:ffff:ffff
152fc6d:9700::/24fc6d:97ff:ffff:ffff:ffff:ffff:ffff:ffff
153fc6d:9800::/24fc6d:98ff:ffff:ffff:ffff:ffff:ffff:ffff
154fc6d:9900::/24fc6d:99ff:ffff:ffff:ffff:ffff:ffff:ffff
155fc6d:9a00::/24fc6d:9aff:ffff:ffff:ffff:ffff:ffff:ffff
156fc6d:9b00::/24fc6d:9bff:ffff:ffff:ffff:ffff:ffff:ffff
157fc6d:9c00::/24fc6d:9cff:ffff:ffff:ffff:ffff:ffff:ffff
158fc6d:9d00::/24fc6d:9dff:ffff:ffff:ffff:ffff:ffff:ffff
159fc6d:9e00::/24fc6d:9eff:ffff:ffff:ffff:ffff:ffff:ffff
160fc6d:9f00::/24fc6d:9fff:ffff:ffff:ffff:ffff:ffff:ffff
161fc6d:a000::/24fc6d:a0ff:ffff:ffff:ffff:ffff:ffff:ffff
162fc6d:a100::/24fc6d:a1ff:ffff:ffff:ffff:ffff:ffff:ffff
163fc6d:a200::/24fc6d:a2ff:ffff:ffff:ffff:ffff:ffff:ffff
164fc6d:a300::/24fc6d:a3ff:ffff:ffff:ffff:ffff:ffff:ffff
165fc6d:a400::/24fc6d:a4ff:ffff:ffff:ffff:ffff:ffff:ffff
166fc6d:a500::/24fc6d:a5ff:ffff:ffff:ffff:ffff:ffff:ffff
167fc6d:a600::/24fc6d:a6ff:ffff:ffff:ffff:ffff:ffff:ffff
168fc6d:a700::/24fc6d:a7ff:ffff:ffff:ffff:ffff:ffff:ffff
169fc6d:a800::/24fc6d:a8ff:ffff:ffff:ffff:ffff:ffff:ffff
170fc6d:a900::/24fc6d:a9ff:ffff:ffff:ffff:ffff:ffff:ffff
171fc6d:aa00::/24fc6d:aaff:ffff:ffff:ffff:ffff:ffff:ffff
172fc6d:ab00::/24fc6d:abff:ffff:ffff:ffff:ffff:ffff:ffff
173fc6d:ac00::/24fc6d:acff:ffff:ffff:ffff:ffff:ffff:ffff
174fc6d:ad00::/24fc6d:adff:ffff:ffff:ffff:ffff:ffff:ffff
175fc6d:ae00::/24fc6d:aeff:ffff:ffff:ffff:ffff:ffff:ffff
176fc6d:af00::/24fc6d:afff:ffff:ffff:ffff:ffff:ffff:ffff
177fc6d:b000::/24fc6d:b0ff:ffff:ffff:ffff:ffff:ffff:ffff
178fc6d:b100::/24fc6d:b1ff:ffff:ffff:ffff:ffff:ffff:ffff
179fc6d:b200::/24fc6d:b2ff:ffff:ffff:ffff:ffff:ffff:ffff
180fc6d:b300::/24fc6d:b3ff:ffff:ffff:ffff:ffff:ffff:ffff
181fc6d:b400::/24fc6d:b4ff:ffff:ffff:ffff:ffff:ffff:ffff
182fc6d:b500::/24fc6d:b5ff:ffff:ffff:ffff:ffff:ffff:ffff
183fc6d:b600::/24fc6d:b6ff:ffff:ffff:ffff:ffff:ffff:ffff
184fc6d:b700::/24fc6d:b7ff:ffff:ffff:ffff:ffff:ffff:ffff
185fc6d:b800::/24fc6d:b8ff:ffff:ffff:ffff:ffff:ffff:ffff
186fc6d:b900::/24fc6d:b9ff:ffff:ffff:ffff:ffff:ffff:ffff
187fc6d:ba00::/24fc6d:baff:ffff:ffff:ffff:ffff:ffff:ffff
188fc6d:bb00::/24fc6d:bbff:ffff:ffff:ffff:ffff:ffff:ffff
189fc6d:bc00::/24fc6d:bcff:ffff:ffff:ffff:ffff:ffff:ffff
190fc6d:bd00::/24fc6d:bdff:ffff:ffff:ffff:ffff:ffff:ffff
191fc6d:be00::/24fc6d:beff:ffff:ffff:ffff:ffff:ffff:ffff
192fc6d:bf00::/24fc6d:bfff:ffff:ffff:ffff:ffff:ffff:ffff
193fc6d:c000::/24fc6d:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
194fc6d:c100::/24fc6d:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
195fc6d:c200::/24fc6d:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
196fc6d:c300::/24fc6d:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
197fc6d:c400::/24fc6d:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
198fc6d:c500::/24fc6d:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
199fc6d:c600::/24fc6d:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
200fc6d:c700::/24fc6d:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
201fc6d:c800::/24fc6d:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
202fc6d:c900::/24fc6d:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
203fc6d:ca00::/24fc6d:caff:ffff:ffff:ffff:ffff:ffff:ffff
204fc6d:cb00::/24fc6d:cbff:ffff:ffff:ffff:ffff:ffff:ffff
205fc6d:cc00::/24fc6d:ccff:ffff:ffff:ffff:ffff:ffff:ffff
206fc6d:cd00::/24fc6d:cdff:ffff:ffff:ffff:ffff:ffff:ffff
207fc6d:ce00::/24fc6d:ceff:ffff:ffff:ffff:ffff:ffff:ffff
208fc6d:cf00::/24fc6d:cfff:ffff:ffff:ffff:ffff:ffff:ffff
209fc6d:d000::/24fc6d:d0ff:ffff:ffff:ffff:ffff:ffff:ffff
210fc6d:d100::/24fc6d:d1ff:ffff:ffff:ffff:ffff:ffff:ffff
211fc6d:d200::/24fc6d:d2ff:ffff:ffff:ffff:ffff:ffff:ffff
212fc6d:d300::/24fc6d:d3ff:ffff:ffff:ffff:ffff:ffff:ffff
213fc6d:d400::/24fc6d:d4ff:ffff:ffff:ffff:ffff:ffff:ffff
214fc6d:d500::/24fc6d:d5ff:ffff:ffff:ffff:ffff:ffff:ffff
215fc6d:d600::/24fc6d:d6ff:ffff:ffff:ffff:ffff:ffff:ffff
216fc6d:d700::/24fc6d:d7ff:ffff:ffff:ffff:ffff:ffff:ffff
217fc6d:d800::/24fc6d:d8ff:ffff:ffff:ffff:ffff:ffff:ffff
218fc6d:d900::/24fc6d:d9ff:ffff:ffff:ffff:ffff:ffff:ffff
219fc6d:da00::/24fc6d:daff:ffff:ffff:ffff:ffff:ffff:ffff
220fc6d:db00::/24fc6d:dbff:ffff:ffff:ffff:ffff:ffff:ffff
221fc6d:dc00::/24fc6d:dcff:ffff:ffff:ffff:ffff:ffff:ffff
222fc6d:dd00::/24fc6d:ddff:ffff:ffff:ffff:ffff:ffff:ffff
223fc6d:de00::/24fc6d:deff:ffff:ffff:ffff:ffff:ffff:ffff
224fc6d:df00::/24fc6d:dfff:ffff:ffff:ffff:ffff:ffff:ffff
225fc6d:e000::/24fc6d:e0ff:ffff:ffff:ffff:ffff:ffff:ffff
226fc6d:e100::/24fc6d:e1ff:ffff:ffff:ffff:ffff:ffff:ffff
227fc6d:e200::/24fc6d:e2ff:ffff:ffff:ffff:ffff:ffff:ffff
228fc6d:e300::/24fc6d:e3ff:ffff:ffff:ffff:ffff:ffff:ffff
229fc6d:e400::/24fc6d:e4ff:ffff:ffff:ffff:ffff:ffff:ffff
230fc6d:e500::/24fc6d:e5ff:ffff:ffff:ffff:ffff:ffff:ffff
231fc6d:e600::/24fc6d:e6ff:ffff:ffff:ffff:ffff:ffff:ffff
232fc6d:e700::/24fc6d:e7ff:ffff:ffff:ffff:ffff:ffff:ffff
233fc6d:e800::/24fc6d:e8ff:ffff:ffff:ffff:ffff:ffff:ffff
234fc6d:e900::/24fc6d:e9ff:ffff:ffff:ffff:ffff:ffff:ffff
235fc6d:ea00::/24fc6d:eaff:ffff:ffff:ffff:ffff:ffff:ffff
236fc6d:eb00::/24fc6d:ebff:ffff:ffff:ffff:ffff:ffff:ffff
237fc6d:ec00::/24fc6d:ecff:ffff:ffff:ffff:ffff:ffff:ffff
238fc6d:ed00::/24fc6d:edff:ffff:ffff:ffff:ffff:ffff:ffff
239fc6d:ee00::/24fc6d:eeff:ffff:ffff:ffff:ffff:ffff:ffff
240fc6d:ef00::/24fc6d:efff:ffff:ffff:ffff:ffff:ffff:ffff
241fc6d:f000::/24fc6d:f0ff:ffff:ffff:ffff:ffff:ffff:ffff
242fc6d:f100::/24fc6d:f1ff:ffff:ffff:ffff:ffff:ffff:ffff
243fc6d:f200::/24fc6d:f2ff:ffff:ffff:ffff:ffff:ffff:ffff
244fc6d:f300::/24fc6d:f3ff:ffff:ffff:ffff:ffff:ffff:ffff
245fc6d:f400::/24fc6d:f4ff:ffff:ffff:ffff:ffff:ffff:ffff
246fc6d:f500::/24fc6d:f5ff:ffff:ffff:ffff:ffff:ffff:ffff
247fc6d:f600::/24fc6d:f6ff:ffff:ffff:ffff:ffff:ffff:ffff
248fc6d:f700::/24fc6d:f7ff:ffff:ffff:ffff:ffff:ffff:ffff
249fc6d:f800::/24fc6d:f8ff:ffff:ffff:ffff:ffff:ffff:ffff
250fc6d:f900::/24fc6d:f9ff:ffff:ffff:ffff:ffff:ffff:ffff
251fc6d:fa00::/24fc6d:faff:ffff:ffff:ffff:ffff:ffff:ffff
252fc6d:fb00::/24fc6d:fbff:ffff:ffff:ffff:ffff:ffff:ffff
253fc6d:fc00::/24fc6d:fcff:ffff:ffff:ffff:ffff:ffff:ffff
254fc6d:fd00::/24fc6d:fdff:ffff:ffff:ffff:ffff:ffff:ffff
255fc6d:fe00::/24fc6d:feff:ffff:ffff:ffff:ffff:ffff:ffff
256fc6d:ff00::/24fc6d: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.