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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.

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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.

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Remote supportLet a Surftec engineer connect to your computer to help you.All workingA full-screen confirmation that everything is up and running.

Surftec

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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
ffd1::/16
First address
ffd1::
Last address
ffd1: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
ffd1:0000:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
1.d.f.f.ip6.arpa
Split into smaller subnets/32
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

ffd1::/16 makes 65,536 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1ffd1::/32ffd1:0:ffff:ffff:ffff:ffff:ffff:ffff
2ffd1:1::/32ffd1:1:ffff:ffff:ffff:ffff:ffff:ffff
3ffd1:2::/32ffd1:2:ffff:ffff:ffff:ffff:ffff:ffff
4ffd1:3::/32ffd1:3:ffff:ffff:ffff:ffff:ffff:ffff
5ffd1:4::/32ffd1:4:ffff:ffff:ffff:ffff:ffff:ffff
6ffd1:5::/32ffd1:5:ffff:ffff:ffff:ffff:ffff:ffff
7ffd1:6::/32ffd1:6:ffff:ffff:ffff:ffff:ffff:ffff
8ffd1:7::/32ffd1:7:ffff:ffff:ffff:ffff:ffff:ffff
9ffd1:8::/32ffd1:8:ffff:ffff:ffff:ffff:ffff:ffff
10ffd1:9::/32ffd1:9:ffff:ffff:ffff:ffff:ffff:ffff
11ffd1:a::/32ffd1:a:ffff:ffff:ffff:ffff:ffff:ffff
12ffd1:b::/32ffd1:b:ffff:ffff:ffff:ffff:ffff:ffff
13ffd1:c::/32ffd1:c:ffff:ffff:ffff:ffff:ffff:ffff
14ffd1:d::/32ffd1:d:ffff:ffff:ffff:ffff:ffff:ffff
15ffd1:e::/32ffd1:e:ffff:ffff:ffff:ffff:ffff:ffff
16ffd1:f::/32ffd1:f:ffff:ffff:ffff:ffff:ffff:ffff
17ffd1:10::/32ffd1:10:ffff:ffff:ffff:ffff:ffff:ffff
18ffd1:11::/32ffd1:11:ffff:ffff:ffff:ffff:ffff:ffff
19ffd1:12::/32ffd1:12:ffff:ffff:ffff:ffff:ffff:ffff
20ffd1:13::/32ffd1:13:ffff:ffff:ffff:ffff:ffff:ffff
21ffd1:14::/32ffd1:14:ffff:ffff:ffff:ffff:ffff:ffff
22ffd1:15::/32ffd1:15:ffff:ffff:ffff:ffff:ffff:ffff
23ffd1:16::/32ffd1:16:ffff:ffff:ffff:ffff:ffff:ffff
24ffd1:17::/32ffd1:17:ffff:ffff:ffff:ffff:ffff:ffff
25ffd1:18::/32ffd1:18:ffff:ffff:ffff:ffff:ffff:ffff
26ffd1:19::/32ffd1:19:ffff:ffff:ffff:ffff:ffff:ffff
27ffd1:1a::/32ffd1:1a:ffff:ffff:ffff:ffff:ffff:ffff
28ffd1:1b::/32ffd1:1b:ffff:ffff:ffff:ffff:ffff:ffff
29ffd1:1c::/32ffd1:1c:ffff:ffff:ffff:ffff:ffff:ffff
30ffd1:1d::/32ffd1:1d:ffff:ffff:ffff:ffff:ffff:ffff
31ffd1:1e::/32ffd1:1e:ffff:ffff:ffff:ffff:ffff:ffff
32ffd1:1f::/32ffd1:1f:ffff:ffff:ffff:ffff:ffff:ffff
33ffd1:20::/32ffd1:20:ffff:ffff:ffff:ffff:ffff:ffff
34ffd1:21::/32ffd1:21:ffff:ffff:ffff:ffff:ffff:ffff
35ffd1:22::/32ffd1:22:ffff:ffff:ffff:ffff:ffff:ffff
36ffd1:23::/32ffd1:23:ffff:ffff:ffff:ffff:ffff:ffff
37ffd1:24::/32ffd1:24:ffff:ffff:ffff:ffff:ffff:ffff
38ffd1:25::/32ffd1:25:ffff:ffff:ffff:ffff:ffff:ffff
39ffd1:26::/32ffd1:26:ffff:ffff:ffff:ffff:ffff:ffff
40ffd1:27::/32ffd1:27:ffff:ffff:ffff:ffff:ffff:ffff
41ffd1:28::/32ffd1:28:ffff:ffff:ffff:ffff:ffff:ffff
42ffd1:29::/32ffd1:29:ffff:ffff:ffff:ffff:ffff:ffff
43ffd1:2a::/32ffd1:2a:ffff:ffff:ffff:ffff:ffff:ffff
44ffd1:2b::/32ffd1:2b:ffff:ffff:ffff:ffff:ffff:ffff
45ffd1:2c::/32ffd1:2c:ffff:ffff:ffff:ffff:ffff:ffff
46ffd1:2d::/32ffd1:2d:ffff:ffff:ffff:ffff:ffff:ffff
47ffd1:2e::/32ffd1:2e:ffff:ffff:ffff:ffff:ffff:ffff
48ffd1:2f::/32ffd1:2f:ffff:ffff:ffff:ffff:ffff:ffff
49ffd1:30::/32ffd1:30:ffff:ffff:ffff:ffff:ffff:ffff
50ffd1:31::/32ffd1:31:ffff:ffff:ffff:ffff:ffff:ffff
51ffd1:32::/32ffd1:32:ffff:ffff:ffff:ffff:ffff:ffff
52ffd1:33::/32ffd1:33:ffff:ffff:ffff:ffff:ffff:ffff
53ffd1:34::/32ffd1:34:ffff:ffff:ffff:ffff:ffff:ffff
54ffd1:35::/32ffd1:35:ffff:ffff:ffff:ffff:ffff:ffff
55ffd1:36::/32ffd1:36:ffff:ffff:ffff:ffff:ffff:ffff
56ffd1:37::/32ffd1:37:ffff:ffff:ffff:ffff:ffff:ffff
57ffd1:38::/32ffd1:38:ffff:ffff:ffff:ffff:ffff:ffff
58ffd1:39::/32ffd1:39:ffff:ffff:ffff:ffff:ffff:ffff
59ffd1:3a::/32ffd1:3a:ffff:ffff:ffff:ffff:ffff:ffff
60ffd1:3b::/32ffd1:3b:ffff:ffff:ffff:ffff:ffff:ffff
61ffd1:3c::/32ffd1:3c:ffff:ffff:ffff:ffff:ffff:ffff
62ffd1:3d::/32ffd1:3d:ffff:ffff:ffff:ffff:ffff:ffff
63ffd1:3e::/32ffd1:3e:ffff:ffff:ffff:ffff:ffff:ffff
64ffd1:3f::/32ffd1:3f:ffff:ffff:ffff:ffff:ffff:ffff
65ffd1:40::/32ffd1:40:ffff:ffff:ffff:ffff:ffff:ffff
66ffd1:41::/32ffd1:41:ffff:ffff:ffff:ffff:ffff:ffff
67ffd1:42::/32ffd1:42:ffff:ffff:ffff:ffff:ffff:ffff
68ffd1:43::/32ffd1:43:ffff:ffff:ffff:ffff:ffff:ffff
69ffd1:44::/32ffd1:44:ffff:ffff:ffff:ffff:ffff:ffff
70ffd1:45::/32ffd1:45:ffff:ffff:ffff:ffff:ffff:ffff
71ffd1:46::/32ffd1:46:ffff:ffff:ffff:ffff:ffff:ffff
72ffd1:47::/32ffd1:47:ffff:ffff:ffff:ffff:ffff:ffff
73ffd1:48::/32ffd1:48:ffff:ffff:ffff:ffff:ffff:ffff
74ffd1:49::/32ffd1:49:ffff:ffff:ffff:ffff:ffff:ffff
75ffd1:4a::/32ffd1:4a:ffff:ffff:ffff:ffff:ffff:ffff
76ffd1:4b::/32ffd1:4b:ffff:ffff:ffff:ffff:ffff:ffff
77ffd1:4c::/32ffd1:4c:ffff:ffff:ffff:ffff:ffff:ffff
78ffd1:4d::/32ffd1:4d:ffff:ffff:ffff:ffff:ffff:ffff
79ffd1:4e::/32ffd1:4e:ffff:ffff:ffff:ffff:ffff:ffff
80ffd1:4f::/32ffd1:4f:ffff:ffff:ffff:ffff:ffff:ffff
81ffd1:50::/32ffd1:50:ffff:ffff:ffff:ffff:ffff:ffff
82ffd1:51::/32ffd1:51:ffff:ffff:ffff:ffff:ffff:ffff
83ffd1:52::/32ffd1:52:ffff:ffff:ffff:ffff:ffff:ffff
84ffd1:53::/32ffd1:53:ffff:ffff:ffff:ffff:ffff:ffff
85ffd1:54::/32ffd1:54:ffff:ffff:ffff:ffff:ffff:ffff
86ffd1:55::/32ffd1:55:ffff:ffff:ffff:ffff:ffff:ffff
87ffd1:56::/32ffd1:56:ffff:ffff:ffff:ffff:ffff:ffff
88ffd1:57::/32ffd1:57:ffff:ffff:ffff:ffff:ffff:ffff
89ffd1:58::/32ffd1:58:ffff:ffff:ffff:ffff:ffff:ffff
90ffd1:59::/32ffd1:59:ffff:ffff:ffff:ffff:ffff:ffff
91ffd1:5a::/32ffd1:5a:ffff:ffff:ffff:ffff:ffff:ffff
92ffd1:5b::/32ffd1:5b:ffff:ffff:ffff:ffff:ffff:ffff
93ffd1:5c::/32ffd1:5c:ffff:ffff:ffff:ffff:ffff:ffff
94ffd1:5d::/32ffd1:5d:ffff:ffff:ffff:ffff:ffff:ffff
95ffd1:5e::/32ffd1:5e:ffff:ffff:ffff:ffff:ffff:ffff
96ffd1:5f::/32ffd1:5f:ffff:ffff:ffff:ffff:ffff:ffff
97ffd1:60::/32ffd1:60:ffff:ffff:ffff:ffff:ffff:ffff
98ffd1:61::/32ffd1:61:ffff:ffff:ffff:ffff:ffff:ffff
99ffd1:62::/32ffd1:62:ffff:ffff:ffff:ffff:ffff:ffff
100ffd1:63::/32ffd1:63:ffff:ffff:ffff:ffff:ffff:ffff
101ffd1:64::/32ffd1:64:ffff:ffff:ffff:ffff:ffff:ffff
102ffd1:65::/32ffd1:65:ffff:ffff:ffff:ffff:ffff:ffff
103ffd1:66::/32ffd1:66:ffff:ffff:ffff:ffff:ffff:ffff
104ffd1:67::/32ffd1:67:ffff:ffff:ffff:ffff:ffff:ffff
105ffd1:68::/32ffd1:68:ffff:ffff:ffff:ffff:ffff:ffff
106ffd1:69::/32ffd1:69:ffff:ffff:ffff:ffff:ffff:ffff
107ffd1:6a::/32ffd1:6a:ffff:ffff:ffff:ffff:ffff:ffff
108ffd1:6b::/32ffd1:6b:ffff:ffff:ffff:ffff:ffff:ffff
109ffd1:6c::/32ffd1:6c:ffff:ffff:ffff:ffff:ffff:ffff
110ffd1:6d::/32ffd1:6d:ffff:ffff:ffff:ffff:ffff:ffff
111ffd1:6e::/32ffd1:6e:ffff:ffff:ffff:ffff:ffff:ffff
112ffd1:6f::/32ffd1:6f:ffff:ffff:ffff:ffff:ffff:ffff
113ffd1:70::/32ffd1:70:ffff:ffff:ffff:ffff:ffff:ffff
114ffd1:71::/32ffd1:71:ffff:ffff:ffff:ffff:ffff:ffff
115ffd1:72::/32ffd1:72:ffff:ffff:ffff:ffff:ffff:ffff
116ffd1:73::/32ffd1:73:ffff:ffff:ffff:ffff:ffff:ffff
117ffd1:74::/32ffd1:74:ffff:ffff:ffff:ffff:ffff:ffff
118ffd1:75::/32ffd1:75:ffff:ffff:ffff:ffff:ffff:ffff
119ffd1:76::/32ffd1:76:ffff:ffff:ffff:ffff:ffff:ffff
120ffd1:77::/32ffd1:77:ffff:ffff:ffff:ffff:ffff:ffff
121ffd1:78::/32ffd1:78:ffff:ffff:ffff:ffff:ffff:ffff
122ffd1:79::/32ffd1:79:ffff:ffff:ffff:ffff:ffff:ffff
123ffd1:7a::/32ffd1:7a:ffff:ffff:ffff:ffff:ffff:ffff
124ffd1:7b::/32ffd1:7b:ffff:ffff:ffff:ffff:ffff:ffff
125ffd1:7c::/32ffd1:7c:ffff:ffff:ffff:ffff:ffff:ffff
126ffd1:7d::/32ffd1:7d:ffff:ffff:ffff:ffff:ffff:ffff
127ffd1:7e::/32ffd1:7e:ffff:ffff:ffff:ffff:ffff:ffff
128ffd1:7f::/32ffd1:7f:ffff:ffff:ffff:ffff:ffff:ffff
129ffd1:80::/32ffd1:80:ffff:ffff:ffff:ffff:ffff:ffff
130ffd1:81::/32ffd1:81:ffff:ffff:ffff:ffff:ffff:ffff
131ffd1:82::/32ffd1:82:ffff:ffff:ffff:ffff:ffff:ffff
132ffd1:83::/32ffd1:83:ffff:ffff:ffff:ffff:ffff:ffff
133ffd1:84::/32ffd1:84:ffff:ffff:ffff:ffff:ffff:ffff
134ffd1:85::/32ffd1:85:ffff:ffff:ffff:ffff:ffff:ffff
135ffd1:86::/32ffd1:86:ffff:ffff:ffff:ffff:ffff:ffff
136ffd1:87::/32ffd1:87:ffff:ffff:ffff:ffff:ffff:ffff
137ffd1:88::/32ffd1:88:ffff:ffff:ffff:ffff:ffff:ffff
138ffd1:89::/32ffd1:89:ffff:ffff:ffff:ffff:ffff:ffff
139ffd1:8a::/32ffd1:8a:ffff:ffff:ffff:ffff:ffff:ffff
140ffd1:8b::/32ffd1:8b:ffff:ffff:ffff:ffff:ffff:ffff
141ffd1:8c::/32ffd1:8c:ffff:ffff:ffff:ffff:ffff:ffff
142ffd1:8d::/32ffd1:8d:ffff:ffff:ffff:ffff:ffff:ffff
143ffd1:8e::/32ffd1:8e:ffff:ffff:ffff:ffff:ffff:ffff
144ffd1:8f::/32ffd1:8f:ffff:ffff:ffff:ffff:ffff:ffff
145ffd1:90::/32ffd1:90:ffff:ffff:ffff:ffff:ffff:ffff
146ffd1:91::/32ffd1:91:ffff:ffff:ffff:ffff:ffff:ffff
147ffd1:92::/32ffd1:92:ffff:ffff:ffff:ffff:ffff:ffff
148ffd1:93::/32ffd1:93:ffff:ffff:ffff:ffff:ffff:ffff
149ffd1:94::/32ffd1:94:ffff:ffff:ffff:ffff:ffff:ffff
150ffd1:95::/32ffd1:95:ffff:ffff:ffff:ffff:ffff:ffff
151ffd1:96::/32ffd1:96:ffff:ffff:ffff:ffff:ffff:ffff
152ffd1:97::/32ffd1:97:ffff:ffff:ffff:ffff:ffff:ffff
153ffd1:98::/32ffd1:98:ffff:ffff:ffff:ffff:ffff:ffff
154ffd1:99::/32ffd1:99:ffff:ffff:ffff:ffff:ffff:ffff
155ffd1:9a::/32ffd1:9a:ffff:ffff:ffff:ffff:ffff:ffff
156ffd1:9b::/32ffd1:9b:ffff:ffff:ffff:ffff:ffff:ffff
157ffd1:9c::/32ffd1:9c:ffff:ffff:ffff:ffff:ffff:ffff
158ffd1:9d::/32ffd1:9d:ffff:ffff:ffff:ffff:ffff:ffff
159ffd1:9e::/32ffd1:9e:ffff:ffff:ffff:ffff:ffff:ffff
160ffd1:9f::/32ffd1:9f:ffff:ffff:ffff:ffff:ffff:ffff
161ffd1:a0::/32ffd1:a0:ffff:ffff:ffff:ffff:ffff:ffff
162ffd1:a1::/32ffd1:a1:ffff:ffff:ffff:ffff:ffff:ffff
163ffd1:a2::/32ffd1:a2:ffff:ffff:ffff:ffff:ffff:ffff
164ffd1:a3::/32ffd1:a3:ffff:ffff:ffff:ffff:ffff:ffff
165ffd1:a4::/32ffd1:a4:ffff:ffff:ffff:ffff:ffff:ffff
166ffd1:a5::/32ffd1:a5:ffff:ffff:ffff:ffff:ffff:ffff
167ffd1:a6::/32ffd1:a6:ffff:ffff:ffff:ffff:ffff:ffff
168ffd1:a7::/32ffd1:a7:ffff:ffff:ffff:ffff:ffff:ffff
169ffd1:a8::/32ffd1:a8:ffff:ffff:ffff:ffff:ffff:ffff
170ffd1:a9::/32ffd1:a9:ffff:ffff:ffff:ffff:ffff:ffff
171ffd1:aa::/32ffd1:aa:ffff:ffff:ffff:ffff:ffff:ffff
172ffd1:ab::/32ffd1:ab:ffff:ffff:ffff:ffff:ffff:ffff
173ffd1:ac::/32ffd1:ac:ffff:ffff:ffff:ffff:ffff:ffff
174ffd1:ad::/32ffd1:ad:ffff:ffff:ffff:ffff:ffff:ffff
175ffd1:ae::/32ffd1:ae:ffff:ffff:ffff:ffff:ffff:ffff
176ffd1:af::/32ffd1:af:ffff:ffff:ffff:ffff:ffff:ffff
177ffd1:b0::/32ffd1:b0:ffff:ffff:ffff:ffff:ffff:ffff
178ffd1:b1::/32ffd1:b1:ffff:ffff:ffff:ffff:ffff:ffff
179ffd1:b2::/32ffd1:b2:ffff:ffff:ffff:ffff:ffff:ffff
180ffd1:b3::/32ffd1:b3:ffff:ffff:ffff:ffff:ffff:ffff
181ffd1:b4::/32ffd1:b4:ffff:ffff:ffff:ffff:ffff:ffff
182ffd1:b5::/32ffd1:b5:ffff:ffff:ffff:ffff:ffff:ffff
183ffd1:b6::/32ffd1:b6:ffff:ffff:ffff:ffff:ffff:ffff
184ffd1:b7::/32ffd1:b7:ffff:ffff:ffff:ffff:ffff:ffff
185ffd1:b8::/32ffd1:b8:ffff:ffff:ffff:ffff:ffff:ffff
186ffd1:b9::/32ffd1:b9:ffff:ffff:ffff:ffff:ffff:ffff
187ffd1:ba::/32ffd1:ba:ffff:ffff:ffff:ffff:ffff:ffff
188ffd1:bb::/32ffd1:bb:ffff:ffff:ffff:ffff:ffff:ffff
189ffd1:bc::/32ffd1:bc:ffff:ffff:ffff:ffff:ffff:ffff
190ffd1:bd::/32ffd1:bd:ffff:ffff:ffff:ffff:ffff:ffff
191ffd1:be::/32ffd1:be:ffff:ffff:ffff:ffff:ffff:ffff
192ffd1:bf::/32ffd1:bf:ffff:ffff:ffff:ffff:ffff:ffff
193ffd1:c0::/32ffd1:c0:ffff:ffff:ffff:ffff:ffff:ffff
194ffd1:c1::/32ffd1:c1:ffff:ffff:ffff:ffff:ffff:ffff
195ffd1:c2::/32ffd1:c2:ffff:ffff:ffff:ffff:ffff:ffff
196ffd1:c3::/32ffd1:c3:ffff:ffff:ffff:ffff:ffff:ffff
197ffd1:c4::/32ffd1:c4:ffff:ffff:ffff:ffff:ffff:ffff
198ffd1:c5::/32ffd1:c5:ffff:ffff:ffff:ffff:ffff:ffff
199ffd1:c6::/32ffd1:c6:ffff:ffff:ffff:ffff:ffff:ffff
200ffd1:c7::/32ffd1:c7:ffff:ffff:ffff:ffff:ffff:ffff
201ffd1:c8::/32ffd1:c8:ffff:ffff:ffff:ffff:ffff:ffff
202ffd1:c9::/32ffd1:c9:ffff:ffff:ffff:ffff:ffff:ffff
203ffd1:ca::/32ffd1:ca:ffff:ffff:ffff:ffff:ffff:ffff
204ffd1:cb::/32ffd1:cb:ffff:ffff:ffff:ffff:ffff:ffff
205ffd1:cc::/32ffd1:cc:ffff:ffff:ffff:ffff:ffff:ffff
206ffd1:cd::/32ffd1:cd:ffff:ffff:ffff:ffff:ffff:ffff
207ffd1:ce::/32ffd1:ce:ffff:ffff:ffff:ffff:ffff:ffff
208ffd1:cf::/32ffd1:cf:ffff:ffff:ffff:ffff:ffff:ffff
209ffd1:d0::/32ffd1:d0:ffff:ffff:ffff:ffff:ffff:ffff
210ffd1:d1::/32ffd1:d1:ffff:ffff:ffff:ffff:ffff:ffff
211ffd1:d2::/32ffd1:d2:ffff:ffff:ffff:ffff:ffff:ffff
212ffd1:d3::/32ffd1:d3:ffff:ffff:ffff:ffff:ffff:ffff
213ffd1:d4::/32ffd1:d4:ffff:ffff:ffff:ffff:ffff:ffff
214ffd1:d5::/32ffd1:d5:ffff:ffff:ffff:ffff:ffff:ffff
215ffd1:d6::/32ffd1:d6:ffff:ffff:ffff:ffff:ffff:ffff
216ffd1:d7::/32ffd1:d7:ffff:ffff:ffff:ffff:ffff:ffff
217ffd1:d8::/32ffd1:d8:ffff:ffff:ffff:ffff:ffff:ffff
218ffd1:d9::/32ffd1:d9:ffff:ffff:ffff:ffff:ffff:ffff
219ffd1:da::/32ffd1:da:ffff:ffff:ffff:ffff:ffff:ffff
220ffd1:db::/32ffd1:db:ffff:ffff:ffff:ffff:ffff:ffff
221ffd1:dc::/32ffd1:dc:ffff:ffff:ffff:ffff:ffff:ffff
222ffd1:dd::/32ffd1:dd:ffff:ffff:ffff:ffff:ffff:ffff
223ffd1:de::/32ffd1:de:ffff:ffff:ffff:ffff:ffff:ffff
224ffd1:df::/32ffd1:df:ffff:ffff:ffff:ffff:ffff:ffff
225ffd1:e0::/32ffd1:e0:ffff:ffff:ffff:ffff:ffff:ffff
226ffd1:e1::/32ffd1:e1:ffff:ffff:ffff:ffff:ffff:ffff
227ffd1:e2::/32ffd1:e2:ffff:ffff:ffff:ffff:ffff:ffff
228ffd1:e3::/32ffd1:e3:ffff:ffff:ffff:ffff:ffff:ffff
229ffd1:e4::/32ffd1:e4:ffff:ffff:ffff:ffff:ffff:ffff
230ffd1:e5::/32ffd1:e5:ffff:ffff:ffff:ffff:ffff:ffff
231ffd1:e6::/32ffd1:e6:ffff:ffff:ffff:ffff:ffff:ffff
232ffd1:e7::/32ffd1:e7:ffff:ffff:ffff:ffff:ffff:ffff
233ffd1:e8::/32ffd1:e8:ffff:ffff:ffff:ffff:ffff:ffff
234ffd1:e9::/32ffd1:e9:ffff:ffff:ffff:ffff:ffff:ffff
235ffd1:ea::/32ffd1:ea:ffff:ffff:ffff:ffff:ffff:ffff
236ffd1:eb::/32ffd1:eb:ffff:ffff:ffff:ffff:ffff:ffff
237ffd1:ec::/32ffd1:ec:ffff:ffff:ffff:ffff:ffff:ffff
238ffd1:ed::/32ffd1:ed:ffff:ffff:ffff:ffff:ffff:ffff
239ffd1:ee::/32ffd1:ee:ffff:ffff:ffff:ffff:ffff:ffff
240ffd1:ef::/32ffd1:ef:ffff:ffff:ffff:ffff:ffff:ffff
241ffd1:f0::/32ffd1:f0:ffff:ffff:ffff:ffff:ffff:ffff
242ffd1:f1::/32ffd1:f1:ffff:ffff:ffff:ffff:ffff:ffff
243ffd1:f2::/32ffd1:f2:ffff:ffff:ffff:ffff:ffff:ffff
244ffd1:f3::/32ffd1:f3:ffff:ffff:ffff:ffff:ffff:ffff
245ffd1:f4::/32ffd1:f4:ffff:ffff:ffff:ffff:ffff:ffff
246ffd1:f5::/32ffd1:f5:ffff:ffff:ffff:ffff:ffff:ffff
247ffd1:f6::/32ffd1:f6:ffff:ffff:ffff:ffff:ffff:ffff
248ffd1:f7::/32ffd1:f7:ffff:ffff:ffff:ffff:ffff:ffff
249ffd1:f8::/32ffd1:f8:ffff:ffff:ffff:ffff:ffff:ffff
250ffd1:f9::/32ffd1:f9:ffff:ffff:ffff:ffff:ffff:ffff
251ffd1:fa::/32ffd1:fa:ffff:ffff:ffff:ffff:ffff:ffff
252ffd1:fb::/32ffd1:fb:ffff:ffff:ffff:ffff:ffff:ffff
253ffd1:fc::/32ffd1:fc:ffff:ffff:ffff:ffff:ffff:ffff
254ffd1:fd::/32ffd1:fd:ffff:ffff:ffff:ffff:ffff:ffff
255ffd1:fe::/32ffd1:fe:ffff:ffff:ffff:ffff:ffff:ffff
256ffd1:ff::/32ffd1:ff: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.