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
fe83:c000::/20
First address
fe83:c000::
Last address
fe83: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
fe83:c000:0000:0000:0000:0000:0000:0000
Type
Link-local fe80::/10
Every IPv6 interface has one; not routed
Reverse DNS zone
c.3.8.e.f.ip6.arpa
Split into smaller subnets/32
/21 (2)/22 (4)/23 (8)/24 (16)/28 (256)/32 (4,096)/36 (65,536)

fe83:c000::/20 makes 4,096 subnets of /32; the first 256 are listed.

Subnets
#SubnetLast address
1fe83:c000::/32fe83:c000:ffff:ffff:ffff:ffff:ffff:ffff
2fe83:c001::/32fe83:c001:ffff:ffff:ffff:ffff:ffff:ffff
3fe83:c002::/32fe83:c002:ffff:ffff:ffff:ffff:ffff:ffff
4fe83:c003::/32fe83:c003:ffff:ffff:ffff:ffff:ffff:ffff
5fe83:c004::/32fe83:c004:ffff:ffff:ffff:ffff:ffff:ffff
6fe83:c005::/32fe83:c005:ffff:ffff:ffff:ffff:ffff:ffff
7fe83:c006::/32fe83:c006:ffff:ffff:ffff:ffff:ffff:ffff
8fe83:c007::/32fe83:c007:ffff:ffff:ffff:ffff:ffff:ffff
9fe83:c008::/32fe83:c008:ffff:ffff:ffff:ffff:ffff:ffff
10fe83:c009::/32fe83:c009:ffff:ffff:ffff:ffff:ffff:ffff
11fe83:c00a::/32fe83:c00a:ffff:ffff:ffff:ffff:ffff:ffff
12fe83:c00b::/32fe83:c00b:ffff:ffff:ffff:ffff:ffff:ffff
13fe83:c00c::/32fe83:c00c:ffff:ffff:ffff:ffff:ffff:ffff
14fe83:c00d::/32fe83:c00d:ffff:ffff:ffff:ffff:ffff:ffff
15fe83:c00e::/32fe83:c00e:ffff:ffff:ffff:ffff:ffff:ffff
16fe83:c00f::/32fe83:c00f:ffff:ffff:ffff:ffff:ffff:ffff
17fe83:c010::/32fe83:c010:ffff:ffff:ffff:ffff:ffff:ffff
18fe83:c011::/32fe83:c011:ffff:ffff:ffff:ffff:ffff:ffff
19fe83:c012::/32fe83:c012:ffff:ffff:ffff:ffff:ffff:ffff
20fe83:c013::/32fe83:c013:ffff:ffff:ffff:ffff:ffff:ffff
21fe83:c014::/32fe83:c014:ffff:ffff:ffff:ffff:ffff:ffff
22fe83:c015::/32fe83:c015:ffff:ffff:ffff:ffff:ffff:ffff
23fe83:c016::/32fe83:c016:ffff:ffff:ffff:ffff:ffff:ffff
24fe83:c017::/32fe83:c017:ffff:ffff:ffff:ffff:ffff:ffff
25fe83:c018::/32fe83:c018:ffff:ffff:ffff:ffff:ffff:ffff
26fe83:c019::/32fe83:c019:ffff:ffff:ffff:ffff:ffff:ffff
27fe83:c01a::/32fe83:c01a:ffff:ffff:ffff:ffff:ffff:ffff
28fe83:c01b::/32fe83:c01b:ffff:ffff:ffff:ffff:ffff:ffff
29fe83:c01c::/32fe83:c01c:ffff:ffff:ffff:ffff:ffff:ffff
30fe83:c01d::/32fe83:c01d:ffff:ffff:ffff:ffff:ffff:ffff
31fe83:c01e::/32fe83:c01e:ffff:ffff:ffff:ffff:ffff:ffff
32fe83:c01f::/32fe83:c01f:ffff:ffff:ffff:ffff:ffff:ffff
33fe83:c020::/32fe83:c020:ffff:ffff:ffff:ffff:ffff:ffff
34fe83:c021::/32fe83:c021:ffff:ffff:ffff:ffff:ffff:ffff
35fe83:c022::/32fe83:c022:ffff:ffff:ffff:ffff:ffff:ffff
36fe83:c023::/32fe83:c023:ffff:ffff:ffff:ffff:ffff:ffff
37fe83:c024::/32fe83:c024:ffff:ffff:ffff:ffff:ffff:ffff
38fe83:c025::/32fe83:c025:ffff:ffff:ffff:ffff:ffff:ffff
39fe83:c026::/32fe83:c026:ffff:ffff:ffff:ffff:ffff:ffff
40fe83:c027::/32fe83:c027:ffff:ffff:ffff:ffff:ffff:ffff
41fe83:c028::/32fe83:c028:ffff:ffff:ffff:ffff:ffff:ffff
42fe83:c029::/32fe83:c029:ffff:ffff:ffff:ffff:ffff:ffff
43fe83:c02a::/32fe83:c02a:ffff:ffff:ffff:ffff:ffff:ffff
44fe83:c02b::/32fe83:c02b:ffff:ffff:ffff:ffff:ffff:ffff
45fe83:c02c::/32fe83:c02c:ffff:ffff:ffff:ffff:ffff:ffff
46fe83:c02d::/32fe83:c02d:ffff:ffff:ffff:ffff:ffff:ffff
47fe83:c02e::/32fe83:c02e:ffff:ffff:ffff:ffff:ffff:ffff
48fe83:c02f::/32fe83:c02f:ffff:ffff:ffff:ffff:ffff:ffff
49fe83:c030::/32fe83:c030:ffff:ffff:ffff:ffff:ffff:ffff
50fe83:c031::/32fe83:c031:ffff:ffff:ffff:ffff:ffff:ffff
51fe83:c032::/32fe83:c032:ffff:ffff:ffff:ffff:ffff:ffff
52fe83:c033::/32fe83:c033:ffff:ffff:ffff:ffff:ffff:ffff
53fe83:c034::/32fe83:c034:ffff:ffff:ffff:ffff:ffff:ffff
54fe83:c035::/32fe83:c035:ffff:ffff:ffff:ffff:ffff:ffff
55fe83:c036::/32fe83:c036:ffff:ffff:ffff:ffff:ffff:ffff
56fe83:c037::/32fe83:c037:ffff:ffff:ffff:ffff:ffff:ffff
57fe83:c038::/32fe83:c038:ffff:ffff:ffff:ffff:ffff:ffff
58fe83:c039::/32fe83:c039:ffff:ffff:ffff:ffff:ffff:ffff
59fe83:c03a::/32fe83:c03a:ffff:ffff:ffff:ffff:ffff:ffff
60fe83:c03b::/32fe83:c03b:ffff:ffff:ffff:ffff:ffff:ffff
61fe83:c03c::/32fe83:c03c:ffff:ffff:ffff:ffff:ffff:ffff
62fe83:c03d::/32fe83:c03d:ffff:ffff:ffff:ffff:ffff:ffff
63fe83:c03e::/32fe83:c03e:ffff:ffff:ffff:ffff:ffff:ffff
64fe83:c03f::/32fe83:c03f:ffff:ffff:ffff:ffff:ffff:ffff
65fe83:c040::/32fe83:c040:ffff:ffff:ffff:ffff:ffff:ffff
66fe83:c041::/32fe83:c041:ffff:ffff:ffff:ffff:ffff:ffff
67fe83:c042::/32fe83:c042:ffff:ffff:ffff:ffff:ffff:ffff
68fe83:c043::/32fe83:c043:ffff:ffff:ffff:ffff:ffff:ffff
69fe83:c044::/32fe83:c044:ffff:ffff:ffff:ffff:ffff:ffff
70fe83:c045::/32fe83:c045:ffff:ffff:ffff:ffff:ffff:ffff
71fe83:c046::/32fe83:c046:ffff:ffff:ffff:ffff:ffff:ffff
72fe83:c047::/32fe83:c047:ffff:ffff:ffff:ffff:ffff:ffff
73fe83:c048::/32fe83:c048:ffff:ffff:ffff:ffff:ffff:ffff
74fe83:c049::/32fe83:c049:ffff:ffff:ffff:ffff:ffff:ffff
75fe83:c04a::/32fe83:c04a:ffff:ffff:ffff:ffff:ffff:ffff
76fe83:c04b::/32fe83:c04b:ffff:ffff:ffff:ffff:ffff:ffff
77fe83:c04c::/32fe83:c04c:ffff:ffff:ffff:ffff:ffff:ffff
78fe83:c04d::/32fe83:c04d:ffff:ffff:ffff:ffff:ffff:ffff
79fe83:c04e::/32fe83:c04e:ffff:ffff:ffff:ffff:ffff:ffff
80fe83:c04f::/32fe83:c04f:ffff:ffff:ffff:ffff:ffff:ffff
81fe83:c050::/32fe83:c050:ffff:ffff:ffff:ffff:ffff:ffff
82fe83:c051::/32fe83:c051:ffff:ffff:ffff:ffff:ffff:ffff
83fe83:c052::/32fe83:c052:ffff:ffff:ffff:ffff:ffff:ffff
84fe83:c053::/32fe83:c053:ffff:ffff:ffff:ffff:ffff:ffff
85fe83:c054::/32fe83:c054:ffff:ffff:ffff:ffff:ffff:ffff
86fe83:c055::/32fe83:c055:ffff:ffff:ffff:ffff:ffff:ffff
87fe83:c056::/32fe83:c056:ffff:ffff:ffff:ffff:ffff:ffff
88fe83:c057::/32fe83:c057:ffff:ffff:ffff:ffff:ffff:ffff
89fe83:c058::/32fe83:c058:ffff:ffff:ffff:ffff:ffff:ffff
90fe83:c059::/32fe83:c059:ffff:ffff:ffff:ffff:ffff:ffff
91fe83:c05a::/32fe83:c05a:ffff:ffff:ffff:ffff:ffff:ffff
92fe83:c05b::/32fe83:c05b:ffff:ffff:ffff:ffff:ffff:ffff
93fe83:c05c::/32fe83:c05c:ffff:ffff:ffff:ffff:ffff:ffff
94fe83:c05d::/32fe83:c05d:ffff:ffff:ffff:ffff:ffff:ffff
95fe83:c05e::/32fe83:c05e:ffff:ffff:ffff:ffff:ffff:ffff
96fe83:c05f::/32fe83:c05f:ffff:ffff:ffff:ffff:ffff:ffff
97fe83:c060::/32fe83:c060:ffff:ffff:ffff:ffff:ffff:ffff
98fe83:c061::/32fe83:c061:ffff:ffff:ffff:ffff:ffff:ffff
99fe83:c062::/32fe83:c062:ffff:ffff:ffff:ffff:ffff:ffff
100fe83:c063::/32fe83:c063:ffff:ffff:ffff:ffff:ffff:ffff
101fe83:c064::/32fe83:c064:ffff:ffff:ffff:ffff:ffff:ffff
102fe83:c065::/32fe83:c065:ffff:ffff:ffff:ffff:ffff:ffff
103fe83:c066::/32fe83:c066:ffff:ffff:ffff:ffff:ffff:ffff
104fe83:c067::/32fe83:c067:ffff:ffff:ffff:ffff:ffff:ffff
105fe83:c068::/32fe83:c068:ffff:ffff:ffff:ffff:ffff:ffff
106fe83:c069::/32fe83:c069:ffff:ffff:ffff:ffff:ffff:ffff
107fe83:c06a::/32fe83:c06a:ffff:ffff:ffff:ffff:ffff:ffff
108fe83:c06b::/32fe83:c06b:ffff:ffff:ffff:ffff:ffff:ffff
109fe83:c06c::/32fe83:c06c:ffff:ffff:ffff:ffff:ffff:ffff
110fe83:c06d::/32fe83:c06d:ffff:ffff:ffff:ffff:ffff:ffff
111fe83:c06e::/32fe83:c06e:ffff:ffff:ffff:ffff:ffff:ffff
112fe83:c06f::/32fe83:c06f:ffff:ffff:ffff:ffff:ffff:ffff
113fe83:c070::/32fe83:c070:ffff:ffff:ffff:ffff:ffff:ffff
114fe83:c071::/32fe83:c071:ffff:ffff:ffff:ffff:ffff:ffff
115fe83:c072::/32fe83:c072:ffff:ffff:ffff:ffff:ffff:ffff
116fe83:c073::/32fe83:c073:ffff:ffff:ffff:ffff:ffff:ffff
117fe83:c074::/32fe83:c074:ffff:ffff:ffff:ffff:ffff:ffff
118fe83:c075::/32fe83:c075:ffff:ffff:ffff:ffff:ffff:ffff
119fe83:c076::/32fe83:c076:ffff:ffff:ffff:ffff:ffff:ffff
120fe83:c077::/32fe83:c077:ffff:ffff:ffff:ffff:ffff:ffff
121fe83:c078::/32fe83:c078:ffff:ffff:ffff:ffff:ffff:ffff
122fe83:c079::/32fe83:c079:ffff:ffff:ffff:ffff:ffff:ffff
123fe83:c07a::/32fe83:c07a:ffff:ffff:ffff:ffff:ffff:ffff
124fe83:c07b::/32fe83:c07b:ffff:ffff:ffff:ffff:ffff:ffff
125fe83:c07c::/32fe83:c07c:ffff:ffff:ffff:ffff:ffff:ffff
126fe83:c07d::/32fe83:c07d:ffff:ffff:ffff:ffff:ffff:ffff
127fe83:c07e::/32fe83:c07e:ffff:ffff:ffff:ffff:ffff:ffff
128fe83:c07f::/32fe83:c07f:ffff:ffff:ffff:ffff:ffff:ffff
129fe83:c080::/32fe83:c080:ffff:ffff:ffff:ffff:ffff:ffff
130fe83:c081::/32fe83:c081:ffff:ffff:ffff:ffff:ffff:ffff
131fe83:c082::/32fe83:c082:ffff:ffff:ffff:ffff:ffff:ffff
132fe83:c083::/32fe83:c083:ffff:ffff:ffff:ffff:ffff:ffff
133fe83:c084::/32fe83:c084:ffff:ffff:ffff:ffff:ffff:ffff
134fe83:c085::/32fe83:c085:ffff:ffff:ffff:ffff:ffff:ffff
135fe83:c086::/32fe83:c086:ffff:ffff:ffff:ffff:ffff:ffff
136fe83:c087::/32fe83:c087:ffff:ffff:ffff:ffff:ffff:ffff
137fe83:c088::/32fe83:c088:ffff:ffff:ffff:ffff:ffff:ffff
138fe83:c089::/32fe83:c089:ffff:ffff:ffff:ffff:ffff:ffff
139fe83:c08a::/32fe83:c08a:ffff:ffff:ffff:ffff:ffff:ffff
140fe83:c08b::/32fe83:c08b:ffff:ffff:ffff:ffff:ffff:ffff
141fe83:c08c::/32fe83:c08c:ffff:ffff:ffff:ffff:ffff:ffff
142fe83:c08d::/32fe83:c08d:ffff:ffff:ffff:ffff:ffff:ffff
143fe83:c08e::/32fe83:c08e:ffff:ffff:ffff:ffff:ffff:ffff
144fe83:c08f::/32fe83:c08f:ffff:ffff:ffff:ffff:ffff:ffff
145fe83:c090::/32fe83:c090:ffff:ffff:ffff:ffff:ffff:ffff
146fe83:c091::/32fe83:c091:ffff:ffff:ffff:ffff:ffff:ffff
147fe83:c092::/32fe83:c092:ffff:ffff:ffff:ffff:ffff:ffff
148fe83:c093::/32fe83:c093:ffff:ffff:ffff:ffff:ffff:ffff
149fe83:c094::/32fe83:c094:ffff:ffff:ffff:ffff:ffff:ffff
150fe83:c095::/32fe83:c095:ffff:ffff:ffff:ffff:ffff:ffff
151fe83:c096::/32fe83:c096:ffff:ffff:ffff:ffff:ffff:ffff
152fe83:c097::/32fe83:c097:ffff:ffff:ffff:ffff:ffff:ffff
153fe83:c098::/32fe83:c098:ffff:ffff:ffff:ffff:ffff:ffff
154fe83:c099::/32fe83:c099:ffff:ffff:ffff:ffff:ffff:ffff
155fe83:c09a::/32fe83:c09a:ffff:ffff:ffff:ffff:ffff:ffff
156fe83:c09b::/32fe83:c09b:ffff:ffff:ffff:ffff:ffff:ffff
157fe83:c09c::/32fe83:c09c:ffff:ffff:ffff:ffff:ffff:ffff
158fe83:c09d::/32fe83:c09d:ffff:ffff:ffff:ffff:ffff:ffff
159fe83:c09e::/32fe83:c09e:ffff:ffff:ffff:ffff:ffff:ffff
160fe83:c09f::/32fe83:c09f:ffff:ffff:ffff:ffff:ffff:ffff
161fe83:c0a0::/32fe83:c0a0:ffff:ffff:ffff:ffff:ffff:ffff
162fe83:c0a1::/32fe83:c0a1:ffff:ffff:ffff:ffff:ffff:ffff
163fe83:c0a2::/32fe83:c0a2:ffff:ffff:ffff:ffff:ffff:ffff
164fe83:c0a3::/32fe83:c0a3:ffff:ffff:ffff:ffff:ffff:ffff
165fe83:c0a4::/32fe83:c0a4:ffff:ffff:ffff:ffff:ffff:ffff
166fe83:c0a5::/32fe83:c0a5:ffff:ffff:ffff:ffff:ffff:ffff
167fe83:c0a6::/32fe83:c0a6:ffff:ffff:ffff:ffff:ffff:ffff
168fe83:c0a7::/32fe83:c0a7:ffff:ffff:ffff:ffff:ffff:ffff
169fe83:c0a8::/32fe83:c0a8:ffff:ffff:ffff:ffff:ffff:ffff
170fe83:c0a9::/32fe83:c0a9:ffff:ffff:ffff:ffff:ffff:ffff
171fe83:c0aa::/32fe83:c0aa:ffff:ffff:ffff:ffff:ffff:ffff
172fe83:c0ab::/32fe83:c0ab:ffff:ffff:ffff:ffff:ffff:ffff
173fe83:c0ac::/32fe83:c0ac:ffff:ffff:ffff:ffff:ffff:ffff
174fe83:c0ad::/32fe83:c0ad:ffff:ffff:ffff:ffff:ffff:ffff
175fe83:c0ae::/32fe83:c0ae:ffff:ffff:ffff:ffff:ffff:ffff
176fe83:c0af::/32fe83:c0af:ffff:ffff:ffff:ffff:ffff:ffff
177fe83:c0b0::/32fe83:c0b0:ffff:ffff:ffff:ffff:ffff:ffff
178fe83:c0b1::/32fe83:c0b1:ffff:ffff:ffff:ffff:ffff:ffff
179fe83:c0b2::/32fe83:c0b2:ffff:ffff:ffff:ffff:ffff:ffff
180fe83:c0b3::/32fe83:c0b3:ffff:ffff:ffff:ffff:ffff:ffff
181fe83:c0b4::/32fe83:c0b4:ffff:ffff:ffff:ffff:ffff:ffff
182fe83:c0b5::/32fe83:c0b5:ffff:ffff:ffff:ffff:ffff:ffff
183fe83:c0b6::/32fe83:c0b6:ffff:ffff:ffff:ffff:ffff:ffff
184fe83:c0b7::/32fe83:c0b7:ffff:ffff:ffff:ffff:ffff:ffff
185fe83:c0b8::/32fe83:c0b8:ffff:ffff:ffff:ffff:ffff:ffff
186fe83:c0b9::/32fe83:c0b9:ffff:ffff:ffff:ffff:ffff:ffff
187fe83:c0ba::/32fe83:c0ba:ffff:ffff:ffff:ffff:ffff:ffff
188fe83:c0bb::/32fe83:c0bb:ffff:ffff:ffff:ffff:ffff:ffff
189fe83:c0bc::/32fe83:c0bc:ffff:ffff:ffff:ffff:ffff:ffff
190fe83:c0bd::/32fe83:c0bd:ffff:ffff:ffff:ffff:ffff:ffff
191fe83:c0be::/32fe83:c0be:ffff:ffff:ffff:ffff:ffff:ffff
192fe83:c0bf::/32fe83:c0bf:ffff:ffff:ffff:ffff:ffff:ffff
193fe83:c0c0::/32fe83:c0c0:ffff:ffff:ffff:ffff:ffff:ffff
194fe83:c0c1::/32fe83:c0c1:ffff:ffff:ffff:ffff:ffff:ffff
195fe83:c0c2::/32fe83:c0c2:ffff:ffff:ffff:ffff:ffff:ffff
196fe83:c0c3::/32fe83:c0c3:ffff:ffff:ffff:ffff:ffff:ffff
197fe83:c0c4::/32fe83:c0c4:ffff:ffff:ffff:ffff:ffff:ffff
198fe83:c0c5::/32fe83:c0c5:ffff:ffff:ffff:ffff:ffff:ffff
199fe83:c0c6::/32fe83:c0c6:ffff:ffff:ffff:ffff:ffff:ffff
200fe83:c0c7::/32fe83:c0c7:ffff:ffff:ffff:ffff:ffff:ffff
201fe83:c0c8::/32fe83:c0c8:ffff:ffff:ffff:ffff:ffff:ffff
202fe83:c0c9::/32fe83:c0c9:ffff:ffff:ffff:ffff:ffff:ffff
203fe83:c0ca::/32fe83:c0ca:ffff:ffff:ffff:ffff:ffff:ffff
204fe83:c0cb::/32fe83:c0cb:ffff:ffff:ffff:ffff:ffff:ffff
205fe83:c0cc::/32fe83:c0cc:ffff:ffff:ffff:ffff:ffff:ffff
206fe83:c0cd::/32fe83:c0cd:ffff:ffff:ffff:ffff:ffff:ffff
207fe83:c0ce::/32fe83:c0ce:ffff:ffff:ffff:ffff:ffff:ffff
208fe83:c0cf::/32fe83:c0cf:ffff:ffff:ffff:ffff:ffff:ffff
209fe83:c0d0::/32fe83:c0d0:ffff:ffff:ffff:ffff:ffff:ffff
210fe83:c0d1::/32fe83:c0d1:ffff:ffff:ffff:ffff:ffff:ffff
211fe83:c0d2::/32fe83:c0d2:ffff:ffff:ffff:ffff:ffff:ffff
212fe83:c0d3::/32fe83:c0d3:ffff:ffff:ffff:ffff:ffff:ffff
213fe83:c0d4::/32fe83:c0d4:ffff:ffff:ffff:ffff:ffff:ffff
214fe83:c0d5::/32fe83:c0d5:ffff:ffff:ffff:ffff:ffff:ffff
215fe83:c0d6::/32fe83:c0d6:ffff:ffff:ffff:ffff:ffff:ffff
216fe83:c0d7::/32fe83:c0d7:ffff:ffff:ffff:ffff:ffff:ffff
217fe83:c0d8::/32fe83:c0d8:ffff:ffff:ffff:ffff:ffff:ffff
218fe83:c0d9::/32fe83:c0d9:ffff:ffff:ffff:ffff:ffff:ffff
219fe83:c0da::/32fe83:c0da:ffff:ffff:ffff:ffff:ffff:ffff
220fe83:c0db::/32fe83:c0db:ffff:ffff:ffff:ffff:ffff:ffff
221fe83:c0dc::/32fe83:c0dc:ffff:ffff:ffff:ffff:ffff:ffff
222fe83:c0dd::/32fe83:c0dd:ffff:ffff:ffff:ffff:ffff:ffff
223fe83:c0de::/32fe83:c0de:ffff:ffff:ffff:ffff:ffff:ffff
224fe83:c0df::/32fe83:c0df:ffff:ffff:ffff:ffff:ffff:ffff
225fe83:c0e0::/32fe83:c0e0:ffff:ffff:ffff:ffff:ffff:ffff
226fe83:c0e1::/32fe83:c0e1:ffff:ffff:ffff:ffff:ffff:ffff
227fe83:c0e2::/32fe83:c0e2:ffff:ffff:ffff:ffff:ffff:ffff
228fe83:c0e3::/32fe83:c0e3:ffff:ffff:ffff:ffff:ffff:ffff
229fe83:c0e4::/32fe83:c0e4:ffff:ffff:ffff:ffff:ffff:ffff
230fe83:c0e5::/32fe83:c0e5:ffff:ffff:ffff:ffff:ffff:ffff
231fe83:c0e6::/32fe83:c0e6:ffff:ffff:ffff:ffff:ffff:ffff
232fe83:c0e7::/32fe83:c0e7:ffff:ffff:ffff:ffff:ffff:ffff
233fe83:c0e8::/32fe83:c0e8:ffff:ffff:ffff:ffff:ffff:ffff
234fe83:c0e9::/32fe83:c0e9:ffff:ffff:ffff:ffff:ffff:ffff
235fe83:c0ea::/32fe83:c0ea:ffff:ffff:ffff:ffff:ffff:ffff
236fe83:c0eb::/32fe83:c0eb:ffff:ffff:ffff:ffff:ffff:ffff
237fe83:c0ec::/32fe83:c0ec:ffff:ffff:ffff:ffff:ffff:ffff
238fe83:c0ed::/32fe83:c0ed:ffff:ffff:ffff:ffff:ffff:ffff
239fe83:c0ee::/32fe83:c0ee:ffff:ffff:ffff:ffff:ffff:ffff
240fe83:c0ef::/32fe83:c0ef:ffff:ffff:ffff:ffff:ffff:ffff
241fe83:c0f0::/32fe83:c0f0:ffff:ffff:ffff:ffff:ffff:ffff
242fe83:c0f1::/32fe83:c0f1:ffff:ffff:ffff:ffff:ffff:ffff
243fe83:c0f2::/32fe83:c0f2:ffff:ffff:ffff:ffff:ffff:ffff
244fe83:c0f3::/32fe83:c0f3:ffff:ffff:ffff:ffff:ffff:ffff
245fe83:c0f4::/32fe83:c0f4:ffff:ffff:ffff:ffff:ffff:ffff
246fe83:c0f5::/32fe83:c0f5:ffff:ffff:ffff:ffff:ffff:ffff
247fe83:c0f6::/32fe83:c0f6:ffff:ffff:ffff:ffff:ffff:ffff
248fe83:c0f7::/32fe83:c0f7:ffff:ffff:ffff:ffff:ffff:ffff
249fe83:c0f8::/32fe83:c0f8:ffff:ffff:ffff:ffff:ffff:ffff
250fe83:c0f9::/32fe83:c0f9:ffff:ffff:ffff:ffff:ffff:ffff
251fe83:c0fa::/32fe83:c0fa:ffff:ffff:ffff:ffff:ffff:ffff
252fe83:c0fb::/32fe83:c0fb:ffff:ffff:ffff:ffff:ffff:ffff
253fe83:c0fc::/32fe83:c0fc:ffff:ffff:ffff:ffff:ffff:ffff
254fe83:c0fd::/32fe83:c0fd:ffff:ffff:ffff:ffff:ffff:ffff
255fe83:c0fe::/32fe83:c0fe:ffff:ffff:ffff:ffff:ffff:ffff
256fe83:c0ff::/32fe83:c0ff: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.