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
feb4::/16
First address
feb4::
Last address
feb4: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
feb4:0000:0000:0000:0000:0000:0000:0000
Type
Link-local fe80::/10
Every IPv6 interface has one; not routed
Reverse DNS zone
4.b.e.f.ip6.arpa
Split into smaller subnets/28
/17 (2)/18 (4)/19 (8)/20 (16)/24 (256)/28 (4,096)/32 (65,536)

feb4::/16 makes 4,096 subnets of /28; the first 256 are listed.

Subnets
#SubnetLast address
1feb4::/28feb4:f:ffff:ffff:ffff:ffff:ffff:ffff
2feb4:10::/28feb4:1f:ffff:ffff:ffff:ffff:ffff:ffff
3feb4:20::/28feb4:2f:ffff:ffff:ffff:ffff:ffff:ffff
4feb4:30::/28feb4:3f:ffff:ffff:ffff:ffff:ffff:ffff
5feb4:40::/28feb4:4f:ffff:ffff:ffff:ffff:ffff:ffff
6feb4:50::/28feb4:5f:ffff:ffff:ffff:ffff:ffff:ffff
7feb4:60::/28feb4:6f:ffff:ffff:ffff:ffff:ffff:ffff
8feb4:70::/28feb4:7f:ffff:ffff:ffff:ffff:ffff:ffff
9feb4:80::/28feb4:8f:ffff:ffff:ffff:ffff:ffff:ffff
10feb4:90::/28feb4:9f:ffff:ffff:ffff:ffff:ffff:ffff
11feb4:a0::/28feb4:af:ffff:ffff:ffff:ffff:ffff:ffff
12feb4:b0::/28feb4:bf:ffff:ffff:ffff:ffff:ffff:ffff
13feb4:c0::/28feb4:cf:ffff:ffff:ffff:ffff:ffff:ffff
14feb4:d0::/28feb4:df:ffff:ffff:ffff:ffff:ffff:ffff
15feb4:e0::/28feb4:ef:ffff:ffff:ffff:ffff:ffff:ffff
16feb4:f0::/28feb4:ff:ffff:ffff:ffff:ffff:ffff:ffff
17feb4:100::/28feb4:10f:ffff:ffff:ffff:ffff:ffff:ffff
18feb4:110::/28feb4:11f:ffff:ffff:ffff:ffff:ffff:ffff
19feb4:120::/28feb4:12f:ffff:ffff:ffff:ffff:ffff:ffff
20feb4:130::/28feb4:13f:ffff:ffff:ffff:ffff:ffff:ffff
21feb4:140::/28feb4:14f:ffff:ffff:ffff:ffff:ffff:ffff
22feb4:150::/28feb4:15f:ffff:ffff:ffff:ffff:ffff:ffff
23feb4:160::/28feb4:16f:ffff:ffff:ffff:ffff:ffff:ffff
24feb4:170::/28feb4:17f:ffff:ffff:ffff:ffff:ffff:ffff
25feb4:180::/28feb4:18f:ffff:ffff:ffff:ffff:ffff:ffff
26feb4:190::/28feb4:19f:ffff:ffff:ffff:ffff:ffff:ffff
27feb4:1a0::/28feb4:1af:ffff:ffff:ffff:ffff:ffff:ffff
28feb4:1b0::/28feb4:1bf:ffff:ffff:ffff:ffff:ffff:ffff
29feb4:1c0::/28feb4:1cf:ffff:ffff:ffff:ffff:ffff:ffff
30feb4:1d0::/28feb4:1df:ffff:ffff:ffff:ffff:ffff:ffff
31feb4:1e0::/28feb4:1ef:ffff:ffff:ffff:ffff:ffff:ffff
32feb4:1f0::/28feb4:1ff:ffff:ffff:ffff:ffff:ffff:ffff
33feb4:200::/28feb4:20f:ffff:ffff:ffff:ffff:ffff:ffff
34feb4:210::/28feb4:21f:ffff:ffff:ffff:ffff:ffff:ffff
35feb4:220::/28feb4:22f:ffff:ffff:ffff:ffff:ffff:ffff
36feb4:230::/28feb4:23f:ffff:ffff:ffff:ffff:ffff:ffff
37feb4:240::/28feb4:24f:ffff:ffff:ffff:ffff:ffff:ffff
38feb4:250::/28feb4:25f:ffff:ffff:ffff:ffff:ffff:ffff
39feb4:260::/28feb4:26f:ffff:ffff:ffff:ffff:ffff:ffff
40feb4:270::/28feb4:27f:ffff:ffff:ffff:ffff:ffff:ffff
41feb4:280::/28feb4:28f:ffff:ffff:ffff:ffff:ffff:ffff
42feb4:290::/28feb4:29f:ffff:ffff:ffff:ffff:ffff:ffff
43feb4:2a0::/28feb4:2af:ffff:ffff:ffff:ffff:ffff:ffff
44feb4:2b0::/28feb4:2bf:ffff:ffff:ffff:ffff:ffff:ffff
45feb4:2c0::/28feb4:2cf:ffff:ffff:ffff:ffff:ffff:ffff
46feb4:2d0::/28feb4:2df:ffff:ffff:ffff:ffff:ffff:ffff
47feb4:2e0::/28feb4:2ef:ffff:ffff:ffff:ffff:ffff:ffff
48feb4:2f0::/28feb4:2ff:ffff:ffff:ffff:ffff:ffff:ffff
49feb4:300::/28feb4:30f:ffff:ffff:ffff:ffff:ffff:ffff
50feb4:310::/28feb4:31f:ffff:ffff:ffff:ffff:ffff:ffff
51feb4:320::/28feb4:32f:ffff:ffff:ffff:ffff:ffff:ffff
52feb4:330::/28feb4:33f:ffff:ffff:ffff:ffff:ffff:ffff
53feb4:340::/28feb4:34f:ffff:ffff:ffff:ffff:ffff:ffff
54feb4:350::/28feb4:35f:ffff:ffff:ffff:ffff:ffff:ffff
55feb4:360::/28feb4:36f:ffff:ffff:ffff:ffff:ffff:ffff
56feb4:370::/28feb4:37f:ffff:ffff:ffff:ffff:ffff:ffff
57feb4:380::/28feb4:38f:ffff:ffff:ffff:ffff:ffff:ffff
58feb4:390::/28feb4:39f:ffff:ffff:ffff:ffff:ffff:ffff
59feb4:3a0::/28feb4:3af:ffff:ffff:ffff:ffff:ffff:ffff
60feb4:3b0::/28feb4:3bf:ffff:ffff:ffff:ffff:ffff:ffff
61feb4:3c0::/28feb4:3cf:ffff:ffff:ffff:ffff:ffff:ffff
62feb4:3d0::/28feb4:3df:ffff:ffff:ffff:ffff:ffff:ffff
63feb4:3e0::/28feb4:3ef:ffff:ffff:ffff:ffff:ffff:ffff
64feb4:3f0::/28feb4:3ff:ffff:ffff:ffff:ffff:ffff:ffff
65feb4:400::/28feb4:40f:ffff:ffff:ffff:ffff:ffff:ffff
66feb4:410::/28feb4:41f:ffff:ffff:ffff:ffff:ffff:ffff
67feb4:420::/28feb4:42f:ffff:ffff:ffff:ffff:ffff:ffff
68feb4:430::/28feb4:43f:ffff:ffff:ffff:ffff:ffff:ffff
69feb4:440::/28feb4:44f:ffff:ffff:ffff:ffff:ffff:ffff
70feb4:450::/28feb4:45f:ffff:ffff:ffff:ffff:ffff:ffff
71feb4:460::/28feb4:46f:ffff:ffff:ffff:ffff:ffff:ffff
72feb4:470::/28feb4:47f:ffff:ffff:ffff:ffff:ffff:ffff
73feb4:480::/28feb4:48f:ffff:ffff:ffff:ffff:ffff:ffff
74feb4:490::/28feb4:49f:ffff:ffff:ffff:ffff:ffff:ffff
75feb4:4a0::/28feb4:4af:ffff:ffff:ffff:ffff:ffff:ffff
76feb4:4b0::/28feb4:4bf:ffff:ffff:ffff:ffff:ffff:ffff
77feb4:4c0::/28feb4:4cf:ffff:ffff:ffff:ffff:ffff:ffff
78feb4:4d0::/28feb4:4df:ffff:ffff:ffff:ffff:ffff:ffff
79feb4:4e0::/28feb4:4ef:ffff:ffff:ffff:ffff:ffff:ffff
80feb4:4f0::/28feb4:4ff:ffff:ffff:ffff:ffff:ffff:ffff
81feb4:500::/28feb4:50f:ffff:ffff:ffff:ffff:ffff:ffff
82feb4:510::/28feb4:51f:ffff:ffff:ffff:ffff:ffff:ffff
83feb4:520::/28feb4:52f:ffff:ffff:ffff:ffff:ffff:ffff
84feb4:530::/28feb4:53f:ffff:ffff:ffff:ffff:ffff:ffff
85feb4:540::/28feb4:54f:ffff:ffff:ffff:ffff:ffff:ffff
86feb4:550::/28feb4:55f:ffff:ffff:ffff:ffff:ffff:ffff
87feb4:560::/28feb4:56f:ffff:ffff:ffff:ffff:ffff:ffff
88feb4:570::/28feb4:57f:ffff:ffff:ffff:ffff:ffff:ffff
89feb4:580::/28feb4:58f:ffff:ffff:ffff:ffff:ffff:ffff
90feb4:590::/28feb4:59f:ffff:ffff:ffff:ffff:ffff:ffff
91feb4:5a0::/28feb4:5af:ffff:ffff:ffff:ffff:ffff:ffff
92feb4:5b0::/28feb4:5bf:ffff:ffff:ffff:ffff:ffff:ffff
93feb4:5c0::/28feb4:5cf:ffff:ffff:ffff:ffff:ffff:ffff
94feb4:5d0::/28feb4:5df:ffff:ffff:ffff:ffff:ffff:ffff
95feb4:5e0::/28feb4:5ef:ffff:ffff:ffff:ffff:ffff:ffff
96feb4:5f0::/28feb4:5ff:ffff:ffff:ffff:ffff:ffff:ffff
97feb4:600::/28feb4:60f:ffff:ffff:ffff:ffff:ffff:ffff
98feb4:610::/28feb4:61f:ffff:ffff:ffff:ffff:ffff:ffff
99feb4:620::/28feb4:62f:ffff:ffff:ffff:ffff:ffff:ffff
100feb4:630::/28feb4:63f:ffff:ffff:ffff:ffff:ffff:ffff
101feb4:640::/28feb4:64f:ffff:ffff:ffff:ffff:ffff:ffff
102feb4:650::/28feb4:65f:ffff:ffff:ffff:ffff:ffff:ffff
103feb4:660::/28feb4:66f:ffff:ffff:ffff:ffff:ffff:ffff
104feb4:670::/28feb4:67f:ffff:ffff:ffff:ffff:ffff:ffff
105feb4:680::/28feb4:68f:ffff:ffff:ffff:ffff:ffff:ffff
106feb4:690::/28feb4:69f:ffff:ffff:ffff:ffff:ffff:ffff
107feb4:6a0::/28feb4:6af:ffff:ffff:ffff:ffff:ffff:ffff
108feb4:6b0::/28feb4:6bf:ffff:ffff:ffff:ffff:ffff:ffff
109feb4:6c0::/28feb4:6cf:ffff:ffff:ffff:ffff:ffff:ffff
110feb4:6d0::/28feb4:6df:ffff:ffff:ffff:ffff:ffff:ffff
111feb4:6e0::/28feb4:6ef:ffff:ffff:ffff:ffff:ffff:ffff
112feb4:6f0::/28feb4:6ff:ffff:ffff:ffff:ffff:ffff:ffff
113feb4:700::/28feb4:70f:ffff:ffff:ffff:ffff:ffff:ffff
114feb4:710::/28feb4:71f:ffff:ffff:ffff:ffff:ffff:ffff
115feb4:720::/28feb4:72f:ffff:ffff:ffff:ffff:ffff:ffff
116feb4:730::/28feb4:73f:ffff:ffff:ffff:ffff:ffff:ffff
117feb4:740::/28feb4:74f:ffff:ffff:ffff:ffff:ffff:ffff
118feb4:750::/28feb4:75f:ffff:ffff:ffff:ffff:ffff:ffff
119feb4:760::/28feb4:76f:ffff:ffff:ffff:ffff:ffff:ffff
120feb4:770::/28feb4:77f:ffff:ffff:ffff:ffff:ffff:ffff
121feb4:780::/28feb4:78f:ffff:ffff:ffff:ffff:ffff:ffff
122feb4:790::/28feb4:79f:ffff:ffff:ffff:ffff:ffff:ffff
123feb4:7a0::/28feb4:7af:ffff:ffff:ffff:ffff:ffff:ffff
124feb4:7b0::/28feb4:7bf:ffff:ffff:ffff:ffff:ffff:ffff
125feb4:7c0::/28feb4:7cf:ffff:ffff:ffff:ffff:ffff:ffff
126feb4:7d0::/28feb4:7df:ffff:ffff:ffff:ffff:ffff:ffff
127feb4:7e0::/28feb4:7ef:ffff:ffff:ffff:ffff:ffff:ffff
128feb4:7f0::/28feb4:7ff:ffff:ffff:ffff:ffff:ffff:ffff
129feb4:800::/28feb4:80f:ffff:ffff:ffff:ffff:ffff:ffff
130feb4:810::/28feb4:81f:ffff:ffff:ffff:ffff:ffff:ffff
131feb4:820::/28feb4:82f:ffff:ffff:ffff:ffff:ffff:ffff
132feb4:830::/28feb4:83f:ffff:ffff:ffff:ffff:ffff:ffff
133feb4:840::/28feb4:84f:ffff:ffff:ffff:ffff:ffff:ffff
134feb4:850::/28feb4:85f:ffff:ffff:ffff:ffff:ffff:ffff
135feb4:860::/28feb4:86f:ffff:ffff:ffff:ffff:ffff:ffff
136feb4:870::/28feb4:87f:ffff:ffff:ffff:ffff:ffff:ffff
137feb4:880::/28feb4:88f:ffff:ffff:ffff:ffff:ffff:ffff
138feb4:890::/28feb4:89f:ffff:ffff:ffff:ffff:ffff:ffff
139feb4:8a0::/28feb4:8af:ffff:ffff:ffff:ffff:ffff:ffff
140feb4:8b0::/28feb4:8bf:ffff:ffff:ffff:ffff:ffff:ffff
141feb4:8c0::/28feb4:8cf:ffff:ffff:ffff:ffff:ffff:ffff
142feb4:8d0::/28feb4:8df:ffff:ffff:ffff:ffff:ffff:ffff
143feb4:8e0::/28feb4:8ef:ffff:ffff:ffff:ffff:ffff:ffff
144feb4:8f0::/28feb4:8ff:ffff:ffff:ffff:ffff:ffff:ffff
145feb4:900::/28feb4:90f:ffff:ffff:ffff:ffff:ffff:ffff
146feb4:910::/28feb4:91f:ffff:ffff:ffff:ffff:ffff:ffff
147feb4:920::/28feb4:92f:ffff:ffff:ffff:ffff:ffff:ffff
148feb4:930::/28feb4:93f:ffff:ffff:ffff:ffff:ffff:ffff
149feb4:940::/28feb4:94f:ffff:ffff:ffff:ffff:ffff:ffff
150feb4:950::/28feb4:95f:ffff:ffff:ffff:ffff:ffff:ffff
151feb4:960::/28feb4:96f:ffff:ffff:ffff:ffff:ffff:ffff
152feb4:970::/28feb4:97f:ffff:ffff:ffff:ffff:ffff:ffff
153feb4:980::/28feb4:98f:ffff:ffff:ffff:ffff:ffff:ffff
154feb4:990::/28feb4:99f:ffff:ffff:ffff:ffff:ffff:ffff
155feb4:9a0::/28feb4:9af:ffff:ffff:ffff:ffff:ffff:ffff
156feb4:9b0::/28feb4:9bf:ffff:ffff:ffff:ffff:ffff:ffff
157feb4:9c0::/28feb4:9cf:ffff:ffff:ffff:ffff:ffff:ffff
158feb4:9d0::/28feb4:9df:ffff:ffff:ffff:ffff:ffff:ffff
159feb4:9e0::/28feb4:9ef:ffff:ffff:ffff:ffff:ffff:ffff
160feb4:9f0::/28feb4:9ff:ffff:ffff:ffff:ffff:ffff:ffff
161feb4:a00::/28feb4:a0f:ffff:ffff:ffff:ffff:ffff:ffff
162feb4:a10::/28feb4:a1f:ffff:ffff:ffff:ffff:ffff:ffff
163feb4:a20::/28feb4:a2f:ffff:ffff:ffff:ffff:ffff:ffff
164feb4:a30::/28feb4:a3f:ffff:ffff:ffff:ffff:ffff:ffff
165feb4:a40::/28feb4:a4f:ffff:ffff:ffff:ffff:ffff:ffff
166feb4:a50::/28feb4:a5f:ffff:ffff:ffff:ffff:ffff:ffff
167feb4:a60::/28feb4:a6f:ffff:ffff:ffff:ffff:ffff:ffff
168feb4:a70::/28feb4:a7f:ffff:ffff:ffff:ffff:ffff:ffff
169feb4:a80::/28feb4:a8f:ffff:ffff:ffff:ffff:ffff:ffff
170feb4:a90::/28feb4:a9f:ffff:ffff:ffff:ffff:ffff:ffff
171feb4:aa0::/28feb4:aaf:ffff:ffff:ffff:ffff:ffff:ffff
172feb4:ab0::/28feb4:abf:ffff:ffff:ffff:ffff:ffff:ffff
173feb4:ac0::/28feb4:acf:ffff:ffff:ffff:ffff:ffff:ffff
174feb4:ad0::/28feb4:adf:ffff:ffff:ffff:ffff:ffff:ffff
175feb4:ae0::/28feb4:aef:ffff:ffff:ffff:ffff:ffff:ffff
176feb4:af0::/28feb4:aff:ffff:ffff:ffff:ffff:ffff:ffff
177feb4:b00::/28feb4:b0f:ffff:ffff:ffff:ffff:ffff:ffff
178feb4:b10::/28feb4:b1f:ffff:ffff:ffff:ffff:ffff:ffff
179feb4:b20::/28feb4:b2f:ffff:ffff:ffff:ffff:ffff:ffff
180feb4:b30::/28feb4:b3f:ffff:ffff:ffff:ffff:ffff:ffff
181feb4:b40::/28feb4:b4f:ffff:ffff:ffff:ffff:ffff:ffff
182feb4:b50::/28feb4:b5f:ffff:ffff:ffff:ffff:ffff:ffff
183feb4:b60::/28feb4:b6f:ffff:ffff:ffff:ffff:ffff:ffff
184feb4:b70::/28feb4:b7f:ffff:ffff:ffff:ffff:ffff:ffff
185feb4:b80::/28feb4:b8f:ffff:ffff:ffff:ffff:ffff:ffff
186feb4:b90::/28feb4:b9f:ffff:ffff:ffff:ffff:ffff:ffff
187feb4:ba0::/28feb4:baf:ffff:ffff:ffff:ffff:ffff:ffff
188feb4:bb0::/28feb4:bbf:ffff:ffff:ffff:ffff:ffff:ffff
189feb4:bc0::/28feb4:bcf:ffff:ffff:ffff:ffff:ffff:ffff
190feb4:bd0::/28feb4:bdf:ffff:ffff:ffff:ffff:ffff:ffff
191feb4:be0::/28feb4:bef:ffff:ffff:ffff:ffff:ffff:ffff
192feb4:bf0::/28feb4:bff:ffff:ffff:ffff:ffff:ffff:ffff
193feb4:c00::/28feb4:c0f:ffff:ffff:ffff:ffff:ffff:ffff
194feb4:c10::/28feb4:c1f:ffff:ffff:ffff:ffff:ffff:ffff
195feb4:c20::/28feb4:c2f:ffff:ffff:ffff:ffff:ffff:ffff
196feb4:c30::/28feb4:c3f:ffff:ffff:ffff:ffff:ffff:ffff
197feb4:c40::/28feb4:c4f:ffff:ffff:ffff:ffff:ffff:ffff
198feb4:c50::/28feb4:c5f:ffff:ffff:ffff:ffff:ffff:ffff
199feb4:c60::/28feb4:c6f:ffff:ffff:ffff:ffff:ffff:ffff
200feb4:c70::/28feb4:c7f:ffff:ffff:ffff:ffff:ffff:ffff
201feb4:c80::/28feb4:c8f:ffff:ffff:ffff:ffff:ffff:ffff
202feb4:c90::/28feb4:c9f:ffff:ffff:ffff:ffff:ffff:ffff
203feb4:ca0::/28feb4:caf:ffff:ffff:ffff:ffff:ffff:ffff
204feb4:cb0::/28feb4:cbf:ffff:ffff:ffff:ffff:ffff:ffff
205feb4:cc0::/28feb4:ccf:ffff:ffff:ffff:ffff:ffff:ffff
206feb4:cd0::/28feb4:cdf:ffff:ffff:ffff:ffff:ffff:ffff
207feb4:ce0::/28feb4:cef:ffff:ffff:ffff:ffff:ffff:ffff
208feb4:cf0::/28feb4:cff:ffff:ffff:ffff:ffff:ffff:ffff
209feb4:d00::/28feb4:d0f:ffff:ffff:ffff:ffff:ffff:ffff
210feb4:d10::/28feb4:d1f:ffff:ffff:ffff:ffff:ffff:ffff
211feb4:d20::/28feb4:d2f:ffff:ffff:ffff:ffff:ffff:ffff
212feb4:d30::/28feb4:d3f:ffff:ffff:ffff:ffff:ffff:ffff
213feb4:d40::/28feb4:d4f:ffff:ffff:ffff:ffff:ffff:ffff
214feb4:d50::/28feb4:d5f:ffff:ffff:ffff:ffff:ffff:ffff
215feb4:d60::/28feb4:d6f:ffff:ffff:ffff:ffff:ffff:ffff
216feb4:d70::/28feb4:d7f:ffff:ffff:ffff:ffff:ffff:ffff
217feb4:d80::/28feb4:d8f:ffff:ffff:ffff:ffff:ffff:ffff
218feb4:d90::/28feb4:d9f:ffff:ffff:ffff:ffff:ffff:ffff
219feb4:da0::/28feb4:daf:ffff:ffff:ffff:ffff:ffff:ffff
220feb4:db0::/28feb4:dbf:ffff:ffff:ffff:ffff:ffff:ffff
221feb4:dc0::/28feb4:dcf:ffff:ffff:ffff:ffff:ffff:ffff
222feb4:dd0::/28feb4:ddf:ffff:ffff:ffff:ffff:ffff:ffff
223feb4:de0::/28feb4:def:ffff:ffff:ffff:ffff:ffff:ffff
224feb4:df0::/28feb4:dff:ffff:ffff:ffff:ffff:ffff:ffff
225feb4:e00::/28feb4:e0f:ffff:ffff:ffff:ffff:ffff:ffff
226feb4:e10::/28feb4:e1f:ffff:ffff:ffff:ffff:ffff:ffff
227feb4:e20::/28feb4:e2f:ffff:ffff:ffff:ffff:ffff:ffff
228feb4:e30::/28feb4:e3f:ffff:ffff:ffff:ffff:ffff:ffff
229feb4:e40::/28feb4:e4f:ffff:ffff:ffff:ffff:ffff:ffff
230feb4:e50::/28feb4:e5f:ffff:ffff:ffff:ffff:ffff:ffff
231feb4:e60::/28feb4:e6f:ffff:ffff:ffff:ffff:ffff:ffff
232feb4:e70::/28feb4:e7f:ffff:ffff:ffff:ffff:ffff:ffff
233feb4:e80::/28feb4:e8f:ffff:ffff:ffff:ffff:ffff:ffff
234feb4:e90::/28feb4:e9f:ffff:ffff:ffff:ffff:ffff:ffff
235feb4:ea0::/28feb4:eaf:ffff:ffff:ffff:ffff:ffff:ffff
236feb4:eb0::/28feb4:ebf:ffff:ffff:ffff:ffff:ffff:ffff
237feb4:ec0::/28feb4:ecf:ffff:ffff:ffff:ffff:ffff:ffff
238feb4:ed0::/28feb4:edf:ffff:ffff:ffff:ffff:ffff:ffff
239feb4:ee0::/28feb4:eef:ffff:ffff:ffff:ffff:ffff:ffff
240feb4:ef0::/28feb4:eff:ffff:ffff:ffff:ffff:ffff:ffff
241feb4:f00::/28feb4:f0f:ffff:ffff:ffff:ffff:ffff:ffff
242feb4:f10::/28feb4:f1f:ffff:ffff:ffff:ffff:ffff:ffff
243feb4:f20::/28feb4:f2f:ffff:ffff:ffff:ffff:ffff:ffff
244feb4:f30::/28feb4:f3f:ffff:ffff:ffff:ffff:ffff:ffff
245feb4:f40::/28feb4:f4f:ffff:ffff:ffff:ffff:ffff:ffff
246feb4:f50::/28feb4:f5f:ffff:ffff:ffff:ffff:ffff:ffff
247feb4:f60::/28feb4:f6f:ffff:ffff:ffff:ffff:ffff:ffff
248feb4:f70::/28feb4:f7f:ffff:ffff:ffff:ffff:ffff:ffff
249feb4:f80::/28feb4:f8f:ffff:ffff:ffff:ffff:ffff:ffff
250feb4:f90::/28feb4:f9f:ffff:ffff:ffff:ffff:ffff:ffff
251feb4:fa0::/28feb4:faf:ffff:ffff:ffff:ffff:ffff:ffff
252feb4:fb0::/28feb4:fbf:ffff:ffff:ffff:ffff:ffff:ffff
253feb4:fc0::/28feb4:fcf:ffff:ffff:ffff:ffff:ffff:ffff
254feb4:fd0::/28feb4:fdf:ffff:ffff:ffff:ffff:ffff:ffff
255feb4:fe0::/28feb4:fef:ffff:ffff:ffff:ffff:ffff:ffff
256feb4:ff0::/28feb4:fff: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.