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/20
Addresses2^108
/64 networks2^44
Network
fe86:c000::/20
First address
fe86:c000::
Last address
fe86:cfff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
324,518,553,658,426,726,783,156,020,576,256 (2^108)
/64 networks (LANs)
17,592,186,044,416 (2^44)
Full form
fe86:c000:0000:0000:0000:0000:0000:0000
Type
Link-local fe80::/10
Every IPv6 interface has one; not routed
Reverse DNS zone
c.6.8.e.f.ip6.arpa
Split into smaller subnets/28
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

fe86:c000::/20 makes 256 subnets of /28.

Subnets
#SubnetLast address
1fe86:c000::/28fe86:c00f:ffff:ffff:ffff:ffff:ffff:ffff
2fe86:c010::/28fe86:c01f:ffff:ffff:ffff:ffff:ffff:ffff
3fe86:c020::/28fe86:c02f:ffff:ffff:ffff:ffff:ffff:ffff
4fe86:c030::/28fe86:c03f:ffff:ffff:ffff:ffff:ffff:ffff
5fe86:c040::/28fe86:c04f:ffff:ffff:ffff:ffff:ffff:ffff
6fe86:c050::/28fe86:c05f:ffff:ffff:ffff:ffff:ffff:ffff
7fe86:c060::/28fe86:c06f:ffff:ffff:ffff:ffff:ffff:ffff
8fe86:c070::/28fe86:c07f:ffff:ffff:ffff:ffff:ffff:ffff
9fe86:c080::/28fe86:c08f:ffff:ffff:ffff:ffff:ffff:ffff
10fe86:c090::/28fe86:c09f:ffff:ffff:ffff:ffff:ffff:ffff
11fe86:c0a0::/28fe86:c0af:ffff:ffff:ffff:ffff:ffff:ffff
12fe86:c0b0::/28fe86:c0bf:ffff:ffff:ffff:ffff:ffff:ffff
13fe86:c0c0::/28fe86:c0cf:ffff:ffff:ffff:ffff:ffff:ffff
14fe86:c0d0::/28fe86:c0df:ffff:ffff:ffff:ffff:ffff:ffff
15fe86:c0e0::/28fe86:c0ef:ffff:ffff:ffff:ffff:ffff:ffff
16fe86:c0f0::/28fe86:c0ff:ffff:ffff:ffff:ffff:ffff:ffff
17fe86:c100::/28fe86:c10f:ffff:ffff:ffff:ffff:ffff:ffff
18fe86:c110::/28fe86:c11f:ffff:ffff:ffff:ffff:ffff:ffff
19fe86:c120::/28fe86:c12f:ffff:ffff:ffff:ffff:ffff:ffff
20fe86:c130::/28fe86:c13f:ffff:ffff:ffff:ffff:ffff:ffff
21fe86:c140::/28fe86:c14f:ffff:ffff:ffff:ffff:ffff:ffff
22fe86:c150::/28fe86:c15f:ffff:ffff:ffff:ffff:ffff:ffff
23fe86:c160::/28fe86:c16f:ffff:ffff:ffff:ffff:ffff:ffff
24fe86:c170::/28fe86:c17f:ffff:ffff:ffff:ffff:ffff:ffff
25fe86:c180::/28fe86:c18f:ffff:ffff:ffff:ffff:ffff:ffff
26fe86:c190::/28fe86:c19f:ffff:ffff:ffff:ffff:ffff:ffff
27fe86:c1a0::/28fe86:c1af:ffff:ffff:ffff:ffff:ffff:ffff
28fe86:c1b0::/28fe86:c1bf:ffff:ffff:ffff:ffff:ffff:ffff
29fe86:c1c0::/28fe86:c1cf:ffff:ffff:ffff:ffff:ffff:ffff
30fe86:c1d0::/28fe86:c1df:ffff:ffff:ffff:ffff:ffff:ffff
31fe86:c1e0::/28fe86:c1ef:ffff:ffff:ffff:ffff:ffff:ffff
32fe86:c1f0::/28fe86:c1ff:ffff:ffff:ffff:ffff:ffff:ffff
33fe86:c200::/28fe86:c20f:ffff:ffff:ffff:ffff:ffff:ffff
34fe86:c210::/28fe86:c21f:ffff:ffff:ffff:ffff:ffff:ffff
35fe86:c220::/28fe86:c22f:ffff:ffff:ffff:ffff:ffff:ffff
36fe86:c230::/28fe86:c23f:ffff:ffff:ffff:ffff:ffff:ffff
37fe86:c240::/28fe86:c24f:ffff:ffff:ffff:ffff:ffff:ffff
38fe86:c250::/28fe86:c25f:ffff:ffff:ffff:ffff:ffff:ffff
39fe86:c260::/28fe86:c26f:ffff:ffff:ffff:ffff:ffff:ffff
40fe86:c270::/28fe86:c27f:ffff:ffff:ffff:ffff:ffff:ffff
41fe86:c280::/28fe86:c28f:ffff:ffff:ffff:ffff:ffff:ffff
42fe86:c290::/28fe86:c29f:ffff:ffff:ffff:ffff:ffff:ffff
43fe86:c2a0::/28fe86:c2af:ffff:ffff:ffff:ffff:ffff:ffff
44fe86:c2b0::/28fe86:c2bf:ffff:ffff:ffff:ffff:ffff:ffff
45fe86:c2c0::/28fe86:c2cf:ffff:ffff:ffff:ffff:ffff:ffff
46fe86:c2d0::/28fe86:c2df:ffff:ffff:ffff:ffff:ffff:ffff
47fe86:c2e0::/28fe86:c2ef:ffff:ffff:ffff:ffff:ffff:ffff
48fe86:c2f0::/28fe86:c2ff:ffff:ffff:ffff:ffff:ffff:ffff
49fe86:c300::/28fe86:c30f:ffff:ffff:ffff:ffff:ffff:ffff
50fe86:c310::/28fe86:c31f:ffff:ffff:ffff:ffff:ffff:ffff
51fe86:c320::/28fe86:c32f:ffff:ffff:ffff:ffff:ffff:ffff
52fe86:c330::/28fe86:c33f:ffff:ffff:ffff:ffff:ffff:ffff
53fe86:c340::/28fe86:c34f:ffff:ffff:ffff:ffff:ffff:ffff
54fe86:c350::/28fe86:c35f:ffff:ffff:ffff:ffff:ffff:ffff
55fe86:c360::/28fe86:c36f:ffff:ffff:ffff:ffff:ffff:ffff
56fe86:c370::/28fe86:c37f:ffff:ffff:ffff:ffff:ffff:ffff
57fe86:c380::/28fe86:c38f:ffff:ffff:ffff:ffff:ffff:ffff
58fe86:c390::/28fe86:c39f:ffff:ffff:ffff:ffff:ffff:ffff
59fe86:c3a0::/28fe86:c3af:ffff:ffff:ffff:ffff:ffff:ffff
60fe86:c3b0::/28fe86:c3bf:ffff:ffff:ffff:ffff:ffff:ffff
61fe86:c3c0::/28fe86:c3cf:ffff:ffff:ffff:ffff:ffff:ffff
62fe86:c3d0::/28fe86:c3df:ffff:ffff:ffff:ffff:ffff:ffff
63fe86:c3e0::/28fe86:c3ef:ffff:ffff:ffff:ffff:ffff:ffff
64fe86:c3f0::/28fe86:c3ff:ffff:ffff:ffff:ffff:ffff:ffff
65fe86:c400::/28fe86:c40f:ffff:ffff:ffff:ffff:ffff:ffff
66fe86:c410::/28fe86:c41f:ffff:ffff:ffff:ffff:ffff:ffff
67fe86:c420::/28fe86:c42f:ffff:ffff:ffff:ffff:ffff:ffff
68fe86:c430::/28fe86:c43f:ffff:ffff:ffff:ffff:ffff:ffff
69fe86:c440::/28fe86:c44f:ffff:ffff:ffff:ffff:ffff:ffff
70fe86:c450::/28fe86:c45f:ffff:ffff:ffff:ffff:ffff:ffff
71fe86:c460::/28fe86:c46f:ffff:ffff:ffff:ffff:ffff:ffff
72fe86:c470::/28fe86:c47f:ffff:ffff:ffff:ffff:ffff:ffff
73fe86:c480::/28fe86:c48f:ffff:ffff:ffff:ffff:ffff:ffff
74fe86:c490::/28fe86:c49f:ffff:ffff:ffff:ffff:ffff:ffff
75fe86:c4a0::/28fe86:c4af:ffff:ffff:ffff:ffff:ffff:ffff
76fe86:c4b0::/28fe86:c4bf:ffff:ffff:ffff:ffff:ffff:ffff
77fe86:c4c0::/28fe86:c4cf:ffff:ffff:ffff:ffff:ffff:ffff
78fe86:c4d0::/28fe86:c4df:ffff:ffff:ffff:ffff:ffff:ffff
79fe86:c4e0::/28fe86:c4ef:ffff:ffff:ffff:ffff:ffff:ffff
80fe86:c4f0::/28fe86:c4ff:ffff:ffff:ffff:ffff:ffff:ffff
81fe86:c500::/28fe86:c50f:ffff:ffff:ffff:ffff:ffff:ffff
82fe86:c510::/28fe86:c51f:ffff:ffff:ffff:ffff:ffff:ffff
83fe86:c520::/28fe86:c52f:ffff:ffff:ffff:ffff:ffff:ffff
84fe86:c530::/28fe86:c53f:ffff:ffff:ffff:ffff:ffff:ffff
85fe86:c540::/28fe86:c54f:ffff:ffff:ffff:ffff:ffff:ffff
86fe86:c550::/28fe86:c55f:ffff:ffff:ffff:ffff:ffff:ffff
87fe86:c560::/28fe86:c56f:ffff:ffff:ffff:ffff:ffff:ffff
88fe86:c570::/28fe86:c57f:ffff:ffff:ffff:ffff:ffff:ffff
89fe86:c580::/28fe86:c58f:ffff:ffff:ffff:ffff:ffff:ffff
90fe86:c590::/28fe86:c59f:ffff:ffff:ffff:ffff:ffff:ffff
91fe86:c5a0::/28fe86:c5af:ffff:ffff:ffff:ffff:ffff:ffff
92fe86:c5b0::/28fe86:c5bf:ffff:ffff:ffff:ffff:ffff:ffff
93fe86:c5c0::/28fe86:c5cf:ffff:ffff:ffff:ffff:ffff:ffff
94fe86:c5d0::/28fe86:c5df:ffff:ffff:ffff:ffff:ffff:ffff
95fe86:c5e0::/28fe86:c5ef:ffff:ffff:ffff:ffff:ffff:ffff
96fe86:c5f0::/28fe86:c5ff:ffff:ffff:ffff:ffff:ffff:ffff
97fe86:c600::/28fe86:c60f:ffff:ffff:ffff:ffff:ffff:ffff
98fe86:c610::/28fe86:c61f:ffff:ffff:ffff:ffff:ffff:ffff
99fe86:c620::/28fe86:c62f:ffff:ffff:ffff:ffff:ffff:ffff
100fe86:c630::/28fe86:c63f:ffff:ffff:ffff:ffff:ffff:ffff
101fe86:c640::/28fe86:c64f:ffff:ffff:ffff:ffff:ffff:ffff
102fe86:c650::/28fe86:c65f:ffff:ffff:ffff:ffff:ffff:ffff
103fe86:c660::/28fe86:c66f:ffff:ffff:ffff:ffff:ffff:ffff
104fe86:c670::/28fe86:c67f:ffff:ffff:ffff:ffff:ffff:ffff
105fe86:c680::/28fe86:c68f:ffff:ffff:ffff:ffff:ffff:ffff
106fe86:c690::/28fe86:c69f:ffff:ffff:ffff:ffff:ffff:ffff
107fe86:c6a0::/28fe86:c6af:ffff:ffff:ffff:ffff:ffff:ffff
108fe86:c6b0::/28fe86:c6bf:ffff:ffff:ffff:ffff:ffff:ffff
109fe86:c6c0::/28fe86:c6cf:ffff:ffff:ffff:ffff:ffff:ffff
110fe86:c6d0::/28fe86:c6df:ffff:ffff:ffff:ffff:ffff:ffff
111fe86:c6e0::/28fe86:c6ef:ffff:ffff:ffff:ffff:ffff:ffff
112fe86:c6f0::/28fe86:c6ff:ffff:ffff:ffff:ffff:ffff:ffff
113fe86:c700::/28fe86:c70f:ffff:ffff:ffff:ffff:ffff:ffff
114fe86:c710::/28fe86:c71f:ffff:ffff:ffff:ffff:ffff:ffff
115fe86:c720::/28fe86:c72f:ffff:ffff:ffff:ffff:ffff:ffff
116fe86:c730::/28fe86:c73f:ffff:ffff:ffff:ffff:ffff:ffff
117fe86:c740::/28fe86:c74f:ffff:ffff:ffff:ffff:ffff:ffff
118fe86:c750::/28fe86:c75f:ffff:ffff:ffff:ffff:ffff:ffff
119fe86:c760::/28fe86:c76f:ffff:ffff:ffff:ffff:ffff:ffff
120fe86:c770::/28fe86:c77f:ffff:ffff:ffff:ffff:ffff:ffff
121fe86:c780::/28fe86:c78f:ffff:ffff:ffff:ffff:ffff:ffff
122fe86:c790::/28fe86:c79f:ffff:ffff:ffff:ffff:ffff:ffff
123fe86:c7a0::/28fe86:c7af:ffff:ffff:ffff:ffff:ffff:ffff
124fe86:c7b0::/28fe86:c7bf:ffff:ffff:ffff:ffff:ffff:ffff
125fe86:c7c0::/28fe86:c7cf:ffff:ffff:ffff:ffff:ffff:ffff
126fe86:c7d0::/28fe86:c7df:ffff:ffff:ffff:ffff:ffff:ffff
127fe86:c7e0::/28fe86:c7ef:ffff:ffff:ffff:ffff:ffff:ffff
128fe86:c7f0::/28fe86:c7ff:ffff:ffff:ffff:ffff:ffff:ffff
129fe86:c800::/28fe86:c80f:ffff:ffff:ffff:ffff:ffff:ffff
130fe86:c810::/28fe86:c81f:ffff:ffff:ffff:ffff:ffff:ffff
131fe86:c820::/28fe86:c82f:ffff:ffff:ffff:ffff:ffff:ffff
132fe86:c830::/28fe86:c83f:ffff:ffff:ffff:ffff:ffff:ffff
133fe86:c840::/28fe86:c84f:ffff:ffff:ffff:ffff:ffff:ffff
134fe86:c850::/28fe86:c85f:ffff:ffff:ffff:ffff:ffff:ffff
135fe86:c860::/28fe86:c86f:ffff:ffff:ffff:ffff:ffff:ffff
136fe86:c870::/28fe86:c87f:ffff:ffff:ffff:ffff:ffff:ffff
137fe86:c880::/28fe86:c88f:ffff:ffff:ffff:ffff:ffff:ffff
138fe86:c890::/28fe86:c89f:ffff:ffff:ffff:ffff:ffff:ffff
139fe86:c8a0::/28fe86:c8af:ffff:ffff:ffff:ffff:ffff:ffff
140fe86:c8b0::/28fe86:c8bf:ffff:ffff:ffff:ffff:ffff:ffff
141fe86:c8c0::/28fe86:c8cf:ffff:ffff:ffff:ffff:ffff:ffff
142fe86:c8d0::/28fe86:c8df:ffff:ffff:ffff:ffff:ffff:ffff
143fe86:c8e0::/28fe86:c8ef:ffff:ffff:ffff:ffff:ffff:ffff
144fe86:c8f0::/28fe86:c8ff:ffff:ffff:ffff:ffff:ffff:ffff
145fe86:c900::/28fe86:c90f:ffff:ffff:ffff:ffff:ffff:ffff
146fe86:c910::/28fe86:c91f:ffff:ffff:ffff:ffff:ffff:ffff
147fe86:c920::/28fe86:c92f:ffff:ffff:ffff:ffff:ffff:ffff
148fe86:c930::/28fe86:c93f:ffff:ffff:ffff:ffff:ffff:ffff
149fe86:c940::/28fe86:c94f:ffff:ffff:ffff:ffff:ffff:ffff
150fe86:c950::/28fe86:c95f:ffff:ffff:ffff:ffff:ffff:ffff
151fe86:c960::/28fe86:c96f:ffff:ffff:ffff:ffff:ffff:ffff
152fe86:c970::/28fe86:c97f:ffff:ffff:ffff:ffff:ffff:ffff
153fe86:c980::/28fe86:c98f:ffff:ffff:ffff:ffff:ffff:ffff
154fe86:c990::/28fe86:c99f:ffff:ffff:ffff:ffff:ffff:ffff
155fe86:c9a0::/28fe86:c9af:ffff:ffff:ffff:ffff:ffff:ffff
156fe86:c9b0::/28fe86:c9bf:ffff:ffff:ffff:ffff:ffff:ffff
157fe86:c9c0::/28fe86:c9cf:ffff:ffff:ffff:ffff:ffff:ffff
158fe86:c9d0::/28fe86:c9df:ffff:ffff:ffff:ffff:ffff:ffff
159fe86:c9e0::/28fe86:c9ef:ffff:ffff:ffff:ffff:ffff:ffff
160fe86:c9f0::/28fe86:c9ff:ffff:ffff:ffff:ffff:ffff:ffff
161fe86:ca00::/28fe86:ca0f:ffff:ffff:ffff:ffff:ffff:ffff
162fe86:ca10::/28fe86:ca1f:ffff:ffff:ffff:ffff:ffff:ffff
163fe86:ca20::/28fe86:ca2f:ffff:ffff:ffff:ffff:ffff:ffff
164fe86:ca30::/28fe86:ca3f:ffff:ffff:ffff:ffff:ffff:ffff
165fe86:ca40::/28fe86:ca4f:ffff:ffff:ffff:ffff:ffff:ffff
166fe86:ca50::/28fe86:ca5f:ffff:ffff:ffff:ffff:ffff:ffff
167fe86:ca60::/28fe86:ca6f:ffff:ffff:ffff:ffff:ffff:ffff
168fe86:ca70::/28fe86:ca7f:ffff:ffff:ffff:ffff:ffff:ffff
169fe86:ca80::/28fe86:ca8f:ffff:ffff:ffff:ffff:ffff:ffff
170fe86:ca90::/28fe86:ca9f:ffff:ffff:ffff:ffff:ffff:ffff
171fe86:caa0::/28fe86:caaf:ffff:ffff:ffff:ffff:ffff:ffff
172fe86:cab0::/28fe86:cabf:ffff:ffff:ffff:ffff:ffff:ffff
173fe86:cac0::/28fe86:cacf:ffff:ffff:ffff:ffff:ffff:ffff
174fe86:cad0::/28fe86:cadf:ffff:ffff:ffff:ffff:ffff:ffff
175fe86:cae0::/28fe86:caef:ffff:ffff:ffff:ffff:ffff:ffff
176fe86:caf0::/28fe86:caff:ffff:ffff:ffff:ffff:ffff:ffff
177fe86:cb00::/28fe86:cb0f:ffff:ffff:ffff:ffff:ffff:ffff
178fe86:cb10::/28fe86:cb1f:ffff:ffff:ffff:ffff:ffff:ffff
179fe86:cb20::/28fe86:cb2f:ffff:ffff:ffff:ffff:ffff:ffff
180fe86:cb30::/28fe86:cb3f:ffff:ffff:ffff:ffff:ffff:ffff
181fe86:cb40::/28fe86:cb4f:ffff:ffff:ffff:ffff:ffff:ffff
182fe86:cb50::/28fe86:cb5f:ffff:ffff:ffff:ffff:ffff:ffff
183fe86:cb60::/28fe86:cb6f:ffff:ffff:ffff:ffff:ffff:ffff
184fe86:cb70::/28fe86:cb7f:ffff:ffff:ffff:ffff:ffff:ffff
185fe86:cb80::/28fe86:cb8f:ffff:ffff:ffff:ffff:ffff:ffff
186fe86:cb90::/28fe86:cb9f:ffff:ffff:ffff:ffff:ffff:ffff
187fe86:cba0::/28fe86:cbaf:ffff:ffff:ffff:ffff:ffff:ffff
188fe86:cbb0::/28fe86:cbbf:ffff:ffff:ffff:ffff:ffff:ffff
189fe86:cbc0::/28fe86:cbcf:ffff:ffff:ffff:ffff:ffff:ffff
190fe86:cbd0::/28fe86:cbdf:ffff:ffff:ffff:ffff:ffff:ffff
191fe86:cbe0::/28fe86:cbef:ffff:ffff:ffff:ffff:ffff:ffff
192fe86:cbf0::/28fe86:cbff:ffff:ffff:ffff:ffff:ffff:ffff
193fe86:cc00::/28fe86:cc0f:ffff:ffff:ffff:ffff:ffff:ffff
194fe86:cc10::/28fe86:cc1f:ffff:ffff:ffff:ffff:ffff:ffff
195fe86:cc20::/28fe86:cc2f:ffff:ffff:ffff:ffff:ffff:ffff
196fe86:cc30::/28fe86:cc3f:ffff:ffff:ffff:ffff:ffff:ffff
197fe86:cc40::/28fe86:cc4f:ffff:ffff:ffff:ffff:ffff:ffff
198fe86:cc50::/28fe86:cc5f:ffff:ffff:ffff:ffff:ffff:ffff
199fe86:cc60::/28fe86:cc6f:ffff:ffff:ffff:ffff:ffff:ffff
200fe86:cc70::/28fe86:cc7f:ffff:ffff:ffff:ffff:ffff:ffff
201fe86:cc80::/28fe86:cc8f:ffff:ffff:ffff:ffff:ffff:ffff
202fe86:cc90::/28fe86:cc9f:ffff:ffff:ffff:ffff:ffff:ffff
203fe86:cca0::/28fe86:ccaf:ffff:ffff:ffff:ffff:ffff:ffff
204fe86:ccb0::/28fe86:ccbf:ffff:ffff:ffff:ffff:ffff:ffff
205fe86:ccc0::/28fe86:cccf:ffff:ffff:ffff:ffff:ffff:ffff
206fe86:ccd0::/28fe86:ccdf:ffff:ffff:ffff:ffff:ffff:ffff
207fe86:cce0::/28fe86:ccef:ffff:ffff:ffff:ffff:ffff:ffff
208fe86:ccf0::/28fe86:ccff:ffff:ffff:ffff:ffff:ffff:ffff
209fe86:cd00::/28fe86:cd0f:ffff:ffff:ffff:ffff:ffff:ffff
210fe86:cd10::/28fe86:cd1f:ffff:ffff:ffff:ffff:ffff:ffff
211fe86:cd20::/28fe86:cd2f:ffff:ffff:ffff:ffff:ffff:ffff
212fe86:cd30::/28fe86:cd3f:ffff:ffff:ffff:ffff:ffff:ffff
213fe86:cd40::/28fe86:cd4f:ffff:ffff:ffff:ffff:ffff:ffff
214fe86:cd50::/28fe86:cd5f:ffff:ffff:ffff:ffff:ffff:ffff
215fe86:cd60::/28fe86:cd6f:ffff:ffff:ffff:ffff:ffff:ffff
216fe86:cd70::/28fe86:cd7f:ffff:ffff:ffff:ffff:ffff:ffff
217fe86:cd80::/28fe86:cd8f:ffff:ffff:ffff:ffff:ffff:ffff
218fe86:cd90::/28fe86:cd9f:ffff:ffff:ffff:ffff:ffff:ffff
219fe86:cda0::/28fe86:cdaf:ffff:ffff:ffff:ffff:ffff:ffff
220fe86:cdb0::/28fe86:cdbf:ffff:ffff:ffff:ffff:ffff:ffff
221fe86:cdc0::/28fe86:cdcf:ffff:ffff:ffff:ffff:ffff:ffff
222fe86:cdd0::/28fe86:cddf:ffff:ffff:ffff:ffff:ffff:ffff
223fe86:cde0::/28fe86:cdef:ffff:ffff:ffff:ffff:ffff:ffff
224fe86:cdf0::/28fe86:cdff:ffff:ffff:ffff:ffff:ffff:ffff
225fe86:ce00::/28fe86:ce0f:ffff:ffff:ffff:ffff:ffff:ffff
226fe86:ce10::/28fe86:ce1f:ffff:ffff:ffff:ffff:ffff:ffff
227fe86:ce20::/28fe86:ce2f:ffff:ffff:ffff:ffff:ffff:ffff
228fe86:ce30::/28fe86:ce3f:ffff:ffff:ffff:ffff:ffff:ffff
229fe86:ce40::/28fe86:ce4f:ffff:ffff:ffff:ffff:ffff:ffff
230fe86:ce50::/28fe86:ce5f:ffff:ffff:ffff:ffff:ffff:ffff
231fe86:ce60::/28fe86:ce6f:ffff:ffff:ffff:ffff:ffff:ffff
232fe86:ce70::/28fe86:ce7f:ffff:ffff:ffff:ffff:ffff:ffff
233fe86:ce80::/28fe86:ce8f:ffff:ffff:ffff:ffff:ffff:ffff
234fe86:ce90::/28fe86:ce9f:ffff:ffff:ffff:ffff:ffff:ffff
235fe86:cea0::/28fe86:ceaf:ffff:ffff:ffff:ffff:ffff:ffff
236fe86:ceb0::/28fe86:cebf:ffff:ffff:ffff:ffff:ffff:ffff
237fe86:cec0::/28fe86:cecf:ffff:ffff:ffff:ffff:ffff:ffff
238fe86:ced0::/28fe86:cedf:ffff:ffff:ffff:ffff:ffff:ffff
239fe86:cee0::/28fe86:ceef:ffff:ffff:ffff:ffff:ffff:ffff
240fe86:cef0::/28fe86:ceff:ffff:ffff:ffff:ffff:ffff:ffff
241fe86:cf00::/28fe86:cf0f:ffff:ffff:ffff:ffff:ffff:ffff
242fe86:cf10::/28fe86:cf1f:ffff:ffff:ffff:ffff:ffff:ffff
243fe86:cf20::/28fe86:cf2f:ffff:ffff:ffff:ffff:ffff:ffff
244fe86:cf30::/28fe86:cf3f:ffff:ffff:ffff:ffff:ffff:ffff
245fe86:cf40::/28fe86:cf4f:ffff:ffff:ffff:ffff:ffff:ffff
246fe86:cf50::/28fe86:cf5f:ffff:ffff:ffff:ffff:ffff:ffff
247fe86:cf60::/28fe86:cf6f:ffff:ffff:ffff:ffff:ffff:ffff
248fe86:cf70::/28fe86:cf7f:ffff:ffff:ffff:ffff:ffff:ffff
249fe86:cf80::/28fe86:cf8f:ffff:ffff:ffff:ffff:ffff:ffff
250fe86:cf90::/28fe86:cf9f:ffff:ffff:ffff:ffff:ffff:ffff
251fe86:cfa0::/28fe86:cfaf:ffff:ffff:ffff:ffff:ffff:ffff
252fe86:cfb0::/28fe86:cfbf:ffff:ffff:ffff:ffff:ffff:ffff
253fe86:cfc0::/28fe86:cfcf:ffff:ffff:ffff:ffff:ffff:ffff
254fe86:cfd0::/28fe86:cfdf:ffff:ffff:ffff:ffff:ffff:ffff
255fe86:cfe0::/28fe86:cfef:ffff:ffff:ffff:ffff:ffff:ffff
256fe86:cff0::/28fe86:cfff: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.