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.

Network219.2.64.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
219.2.64.0
Broadcast address
219.2.127.255
First usable
219.2.64.1
Last usable
219.2.127.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Public public
Old class
C (default /24)
As numbers
Hex DB024000 · Integer 3674357760 to 3674374143
Reverse DNS zones
64.2.219.in-addr.arpa
65.2.219.in-addr.arpa
66.2.219.in-addr.arpa
67.2.219.in-addr.arpa
68.2.219.in-addr.arpa
69.2.219.in-addr.arpa
70.2.219.in-addr.arpa
71.2.219.in-addr.arpa
72.2.219.in-addr.arpa
73.2.219.in-addr.arpa
74.2.219.in-addr.arpa
75.2.219.in-addr.arpa
76.2.219.in-addr.arpa
77.2.219.in-addr.arpa
78.2.219.in-addr.arpa
79.2.219.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011011.00000010.01000000.00000000219.2.64.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network11011011.00000010.01000000.00000000219.2.64.0
Broadcast11011011.00000010.01111111.11111111219.2.127.255
Split into smaller subnets/29
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

219.2.64.0/18 makes 2,048 subnets of /29; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1219.2.64.0/29219.2.64.1 to 219.2.64.6219.2.64.76
2219.2.64.8/29219.2.64.9 to 219.2.64.14219.2.64.156
3219.2.64.16/29219.2.64.17 to 219.2.64.22219.2.64.236
4219.2.64.24/29219.2.64.25 to 219.2.64.30219.2.64.316
5219.2.64.32/29219.2.64.33 to 219.2.64.38219.2.64.396
6219.2.64.40/29219.2.64.41 to 219.2.64.46219.2.64.476
7219.2.64.48/29219.2.64.49 to 219.2.64.54219.2.64.556
8219.2.64.56/29219.2.64.57 to 219.2.64.62219.2.64.636
9219.2.64.64/29219.2.64.65 to 219.2.64.70219.2.64.716
10219.2.64.72/29219.2.64.73 to 219.2.64.78219.2.64.796
11219.2.64.80/29219.2.64.81 to 219.2.64.86219.2.64.876
12219.2.64.88/29219.2.64.89 to 219.2.64.94219.2.64.956
13219.2.64.96/29219.2.64.97 to 219.2.64.102219.2.64.1036
14219.2.64.104/29219.2.64.105 to 219.2.64.110219.2.64.1116
15219.2.64.112/29219.2.64.113 to 219.2.64.118219.2.64.1196
16219.2.64.120/29219.2.64.121 to 219.2.64.126219.2.64.1276
17219.2.64.128/29219.2.64.129 to 219.2.64.134219.2.64.1356
18219.2.64.136/29219.2.64.137 to 219.2.64.142219.2.64.1436
19219.2.64.144/29219.2.64.145 to 219.2.64.150219.2.64.1516
20219.2.64.152/29219.2.64.153 to 219.2.64.158219.2.64.1596
21219.2.64.160/29219.2.64.161 to 219.2.64.166219.2.64.1676
22219.2.64.168/29219.2.64.169 to 219.2.64.174219.2.64.1756
23219.2.64.176/29219.2.64.177 to 219.2.64.182219.2.64.1836
24219.2.64.184/29219.2.64.185 to 219.2.64.190219.2.64.1916
25219.2.64.192/29219.2.64.193 to 219.2.64.198219.2.64.1996
26219.2.64.200/29219.2.64.201 to 219.2.64.206219.2.64.2076
27219.2.64.208/29219.2.64.209 to 219.2.64.214219.2.64.2156
28219.2.64.216/29219.2.64.217 to 219.2.64.222219.2.64.2236
29219.2.64.224/29219.2.64.225 to 219.2.64.230219.2.64.2316
30219.2.64.232/29219.2.64.233 to 219.2.64.238219.2.64.2396
31219.2.64.240/29219.2.64.241 to 219.2.64.246219.2.64.2476
32219.2.64.248/29219.2.64.249 to 219.2.64.254219.2.64.2556
33219.2.65.0/29219.2.65.1 to 219.2.65.6219.2.65.76
34219.2.65.8/29219.2.65.9 to 219.2.65.14219.2.65.156
35219.2.65.16/29219.2.65.17 to 219.2.65.22219.2.65.236
36219.2.65.24/29219.2.65.25 to 219.2.65.30219.2.65.316
37219.2.65.32/29219.2.65.33 to 219.2.65.38219.2.65.396
38219.2.65.40/29219.2.65.41 to 219.2.65.46219.2.65.476
39219.2.65.48/29219.2.65.49 to 219.2.65.54219.2.65.556
40219.2.65.56/29219.2.65.57 to 219.2.65.62219.2.65.636
41219.2.65.64/29219.2.65.65 to 219.2.65.70219.2.65.716
42219.2.65.72/29219.2.65.73 to 219.2.65.78219.2.65.796
43219.2.65.80/29219.2.65.81 to 219.2.65.86219.2.65.876
44219.2.65.88/29219.2.65.89 to 219.2.65.94219.2.65.956
45219.2.65.96/29219.2.65.97 to 219.2.65.102219.2.65.1036
46219.2.65.104/29219.2.65.105 to 219.2.65.110219.2.65.1116
47219.2.65.112/29219.2.65.113 to 219.2.65.118219.2.65.1196
48219.2.65.120/29219.2.65.121 to 219.2.65.126219.2.65.1276
49219.2.65.128/29219.2.65.129 to 219.2.65.134219.2.65.1356
50219.2.65.136/29219.2.65.137 to 219.2.65.142219.2.65.1436
51219.2.65.144/29219.2.65.145 to 219.2.65.150219.2.65.1516
52219.2.65.152/29219.2.65.153 to 219.2.65.158219.2.65.1596
53219.2.65.160/29219.2.65.161 to 219.2.65.166219.2.65.1676
54219.2.65.168/29219.2.65.169 to 219.2.65.174219.2.65.1756
55219.2.65.176/29219.2.65.177 to 219.2.65.182219.2.65.1836
56219.2.65.184/29219.2.65.185 to 219.2.65.190219.2.65.1916
57219.2.65.192/29219.2.65.193 to 219.2.65.198219.2.65.1996
58219.2.65.200/29219.2.65.201 to 219.2.65.206219.2.65.2076
59219.2.65.208/29219.2.65.209 to 219.2.65.214219.2.65.2156
60219.2.65.216/29219.2.65.217 to 219.2.65.222219.2.65.2236
61219.2.65.224/29219.2.65.225 to 219.2.65.230219.2.65.2316
62219.2.65.232/29219.2.65.233 to 219.2.65.238219.2.65.2396
63219.2.65.240/29219.2.65.241 to 219.2.65.246219.2.65.2476
64219.2.65.248/29219.2.65.249 to 219.2.65.254219.2.65.2556
65219.2.66.0/29219.2.66.1 to 219.2.66.6219.2.66.76
66219.2.66.8/29219.2.66.9 to 219.2.66.14219.2.66.156
67219.2.66.16/29219.2.66.17 to 219.2.66.22219.2.66.236
68219.2.66.24/29219.2.66.25 to 219.2.66.30219.2.66.316
69219.2.66.32/29219.2.66.33 to 219.2.66.38219.2.66.396
70219.2.66.40/29219.2.66.41 to 219.2.66.46219.2.66.476
71219.2.66.48/29219.2.66.49 to 219.2.66.54219.2.66.556
72219.2.66.56/29219.2.66.57 to 219.2.66.62219.2.66.636
73219.2.66.64/29219.2.66.65 to 219.2.66.70219.2.66.716
74219.2.66.72/29219.2.66.73 to 219.2.66.78219.2.66.796
75219.2.66.80/29219.2.66.81 to 219.2.66.86219.2.66.876
76219.2.66.88/29219.2.66.89 to 219.2.66.94219.2.66.956
77219.2.66.96/29219.2.66.97 to 219.2.66.102219.2.66.1036
78219.2.66.104/29219.2.66.105 to 219.2.66.110219.2.66.1116
79219.2.66.112/29219.2.66.113 to 219.2.66.118219.2.66.1196
80219.2.66.120/29219.2.66.121 to 219.2.66.126219.2.66.1276
81219.2.66.128/29219.2.66.129 to 219.2.66.134219.2.66.1356
82219.2.66.136/29219.2.66.137 to 219.2.66.142219.2.66.1436
83219.2.66.144/29219.2.66.145 to 219.2.66.150219.2.66.1516
84219.2.66.152/29219.2.66.153 to 219.2.66.158219.2.66.1596
85219.2.66.160/29219.2.66.161 to 219.2.66.166219.2.66.1676
86219.2.66.168/29219.2.66.169 to 219.2.66.174219.2.66.1756
87219.2.66.176/29219.2.66.177 to 219.2.66.182219.2.66.1836
88219.2.66.184/29219.2.66.185 to 219.2.66.190219.2.66.1916
89219.2.66.192/29219.2.66.193 to 219.2.66.198219.2.66.1996
90219.2.66.200/29219.2.66.201 to 219.2.66.206219.2.66.2076
91219.2.66.208/29219.2.66.209 to 219.2.66.214219.2.66.2156
92219.2.66.216/29219.2.66.217 to 219.2.66.222219.2.66.2236
93219.2.66.224/29219.2.66.225 to 219.2.66.230219.2.66.2316
94219.2.66.232/29219.2.66.233 to 219.2.66.238219.2.66.2396
95219.2.66.240/29219.2.66.241 to 219.2.66.246219.2.66.2476
96219.2.66.248/29219.2.66.249 to 219.2.66.254219.2.66.2556
97219.2.67.0/29219.2.67.1 to 219.2.67.6219.2.67.76
98219.2.67.8/29219.2.67.9 to 219.2.67.14219.2.67.156
99219.2.67.16/29219.2.67.17 to 219.2.67.22219.2.67.236
100219.2.67.24/29219.2.67.25 to 219.2.67.30219.2.67.316
101219.2.67.32/29219.2.67.33 to 219.2.67.38219.2.67.396
102219.2.67.40/29219.2.67.41 to 219.2.67.46219.2.67.476
103219.2.67.48/29219.2.67.49 to 219.2.67.54219.2.67.556
104219.2.67.56/29219.2.67.57 to 219.2.67.62219.2.67.636
105219.2.67.64/29219.2.67.65 to 219.2.67.70219.2.67.716
106219.2.67.72/29219.2.67.73 to 219.2.67.78219.2.67.796
107219.2.67.80/29219.2.67.81 to 219.2.67.86219.2.67.876
108219.2.67.88/29219.2.67.89 to 219.2.67.94219.2.67.956
109219.2.67.96/29219.2.67.97 to 219.2.67.102219.2.67.1036
110219.2.67.104/29219.2.67.105 to 219.2.67.110219.2.67.1116
111219.2.67.112/29219.2.67.113 to 219.2.67.118219.2.67.1196
112219.2.67.120/29219.2.67.121 to 219.2.67.126219.2.67.1276
113219.2.67.128/29219.2.67.129 to 219.2.67.134219.2.67.1356
114219.2.67.136/29219.2.67.137 to 219.2.67.142219.2.67.1436
115219.2.67.144/29219.2.67.145 to 219.2.67.150219.2.67.1516
116219.2.67.152/29219.2.67.153 to 219.2.67.158219.2.67.1596
117219.2.67.160/29219.2.67.161 to 219.2.67.166219.2.67.1676
118219.2.67.168/29219.2.67.169 to 219.2.67.174219.2.67.1756
119219.2.67.176/29219.2.67.177 to 219.2.67.182219.2.67.1836
120219.2.67.184/29219.2.67.185 to 219.2.67.190219.2.67.1916
121219.2.67.192/29219.2.67.193 to 219.2.67.198219.2.67.1996
122219.2.67.200/29219.2.67.201 to 219.2.67.206219.2.67.2076
123219.2.67.208/29219.2.67.209 to 219.2.67.214219.2.67.2156
124219.2.67.216/29219.2.67.217 to 219.2.67.222219.2.67.2236
125219.2.67.224/29219.2.67.225 to 219.2.67.230219.2.67.2316
126219.2.67.232/29219.2.67.233 to 219.2.67.238219.2.67.2396
127219.2.67.240/29219.2.67.241 to 219.2.67.246219.2.67.2476
128219.2.67.248/29219.2.67.249 to 219.2.67.254219.2.67.2556
129219.2.68.0/29219.2.68.1 to 219.2.68.6219.2.68.76
130219.2.68.8/29219.2.68.9 to 219.2.68.14219.2.68.156
131219.2.68.16/29219.2.68.17 to 219.2.68.22219.2.68.236
132219.2.68.24/29219.2.68.25 to 219.2.68.30219.2.68.316
133219.2.68.32/29219.2.68.33 to 219.2.68.38219.2.68.396
134219.2.68.40/29219.2.68.41 to 219.2.68.46219.2.68.476
135219.2.68.48/29219.2.68.49 to 219.2.68.54219.2.68.556
136219.2.68.56/29219.2.68.57 to 219.2.68.62219.2.68.636
137219.2.68.64/29219.2.68.65 to 219.2.68.70219.2.68.716
138219.2.68.72/29219.2.68.73 to 219.2.68.78219.2.68.796
139219.2.68.80/29219.2.68.81 to 219.2.68.86219.2.68.876
140219.2.68.88/29219.2.68.89 to 219.2.68.94219.2.68.956
141219.2.68.96/29219.2.68.97 to 219.2.68.102219.2.68.1036
142219.2.68.104/29219.2.68.105 to 219.2.68.110219.2.68.1116
143219.2.68.112/29219.2.68.113 to 219.2.68.118219.2.68.1196
144219.2.68.120/29219.2.68.121 to 219.2.68.126219.2.68.1276
145219.2.68.128/29219.2.68.129 to 219.2.68.134219.2.68.1356
146219.2.68.136/29219.2.68.137 to 219.2.68.142219.2.68.1436
147219.2.68.144/29219.2.68.145 to 219.2.68.150219.2.68.1516
148219.2.68.152/29219.2.68.153 to 219.2.68.158219.2.68.1596
149219.2.68.160/29219.2.68.161 to 219.2.68.166219.2.68.1676
150219.2.68.168/29219.2.68.169 to 219.2.68.174219.2.68.1756
151219.2.68.176/29219.2.68.177 to 219.2.68.182219.2.68.1836
152219.2.68.184/29219.2.68.185 to 219.2.68.190219.2.68.1916
153219.2.68.192/29219.2.68.193 to 219.2.68.198219.2.68.1996
154219.2.68.200/29219.2.68.201 to 219.2.68.206219.2.68.2076
155219.2.68.208/29219.2.68.209 to 219.2.68.214219.2.68.2156
156219.2.68.216/29219.2.68.217 to 219.2.68.222219.2.68.2236
157219.2.68.224/29219.2.68.225 to 219.2.68.230219.2.68.2316
158219.2.68.232/29219.2.68.233 to 219.2.68.238219.2.68.2396
159219.2.68.240/29219.2.68.241 to 219.2.68.246219.2.68.2476
160219.2.68.248/29219.2.68.249 to 219.2.68.254219.2.68.2556
161219.2.69.0/29219.2.69.1 to 219.2.69.6219.2.69.76
162219.2.69.8/29219.2.69.9 to 219.2.69.14219.2.69.156
163219.2.69.16/29219.2.69.17 to 219.2.69.22219.2.69.236
164219.2.69.24/29219.2.69.25 to 219.2.69.30219.2.69.316
165219.2.69.32/29219.2.69.33 to 219.2.69.38219.2.69.396
166219.2.69.40/29219.2.69.41 to 219.2.69.46219.2.69.476
167219.2.69.48/29219.2.69.49 to 219.2.69.54219.2.69.556
168219.2.69.56/29219.2.69.57 to 219.2.69.62219.2.69.636
169219.2.69.64/29219.2.69.65 to 219.2.69.70219.2.69.716
170219.2.69.72/29219.2.69.73 to 219.2.69.78219.2.69.796
171219.2.69.80/29219.2.69.81 to 219.2.69.86219.2.69.876
172219.2.69.88/29219.2.69.89 to 219.2.69.94219.2.69.956
173219.2.69.96/29219.2.69.97 to 219.2.69.102219.2.69.1036
174219.2.69.104/29219.2.69.105 to 219.2.69.110219.2.69.1116
175219.2.69.112/29219.2.69.113 to 219.2.69.118219.2.69.1196
176219.2.69.120/29219.2.69.121 to 219.2.69.126219.2.69.1276
177219.2.69.128/29219.2.69.129 to 219.2.69.134219.2.69.1356
178219.2.69.136/29219.2.69.137 to 219.2.69.142219.2.69.1436
179219.2.69.144/29219.2.69.145 to 219.2.69.150219.2.69.1516
180219.2.69.152/29219.2.69.153 to 219.2.69.158219.2.69.1596
181219.2.69.160/29219.2.69.161 to 219.2.69.166219.2.69.1676
182219.2.69.168/29219.2.69.169 to 219.2.69.174219.2.69.1756
183219.2.69.176/29219.2.69.177 to 219.2.69.182219.2.69.1836
184219.2.69.184/29219.2.69.185 to 219.2.69.190219.2.69.1916
185219.2.69.192/29219.2.69.193 to 219.2.69.198219.2.69.1996
186219.2.69.200/29219.2.69.201 to 219.2.69.206219.2.69.2076
187219.2.69.208/29219.2.69.209 to 219.2.69.214219.2.69.2156
188219.2.69.216/29219.2.69.217 to 219.2.69.222219.2.69.2236
189219.2.69.224/29219.2.69.225 to 219.2.69.230219.2.69.2316
190219.2.69.232/29219.2.69.233 to 219.2.69.238219.2.69.2396
191219.2.69.240/29219.2.69.241 to 219.2.69.246219.2.69.2476
192219.2.69.248/29219.2.69.249 to 219.2.69.254219.2.69.2556
193219.2.70.0/29219.2.70.1 to 219.2.70.6219.2.70.76
194219.2.70.8/29219.2.70.9 to 219.2.70.14219.2.70.156
195219.2.70.16/29219.2.70.17 to 219.2.70.22219.2.70.236
196219.2.70.24/29219.2.70.25 to 219.2.70.30219.2.70.316
197219.2.70.32/29219.2.70.33 to 219.2.70.38219.2.70.396
198219.2.70.40/29219.2.70.41 to 219.2.70.46219.2.70.476
199219.2.70.48/29219.2.70.49 to 219.2.70.54219.2.70.556
200219.2.70.56/29219.2.70.57 to 219.2.70.62219.2.70.636
201219.2.70.64/29219.2.70.65 to 219.2.70.70219.2.70.716
202219.2.70.72/29219.2.70.73 to 219.2.70.78219.2.70.796
203219.2.70.80/29219.2.70.81 to 219.2.70.86219.2.70.876
204219.2.70.88/29219.2.70.89 to 219.2.70.94219.2.70.956
205219.2.70.96/29219.2.70.97 to 219.2.70.102219.2.70.1036
206219.2.70.104/29219.2.70.105 to 219.2.70.110219.2.70.1116
207219.2.70.112/29219.2.70.113 to 219.2.70.118219.2.70.1196
208219.2.70.120/29219.2.70.121 to 219.2.70.126219.2.70.1276
209219.2.70.128/29219.2.70.129 to 219.2.70.134219.2.70.1356
210219.2.70.136/29219.2.70.137 to 219.2.70.142219.2.70.1436
211219.2.70.144/29219.2.70.145 to 219.2.70.150219.2.70.1516
212219.2.70.152/29219.2.70.153 to 219.2.70.158219.2.70.1596
213219.2.70.160/29219.2.70.161 to 219.2.70.166219.2.70.1676
214219.2.70.168/29219.2.70.169 to 219.2.70.174219.2.70.1756
215219.2.70.176/29219.2.70.177 to 219.2.70.182219.2.70.1836
216219.2.70.184/29219.2.70.185 to 219.2.70.190219.2.70.1916
217219.2.70.192/29219.2.70.193 to 219.2.70.198219.2.70.1996
218219.2.70.200/29219.2.70.201 to 219.2.70.206219.2.70.2076
219219.2.70.208/29219.2.70.209 to 219.2.70.214219.2.70.2156
220219.2.70.216/29219.2.70.217 to 219.2.70.222219.2.70.2236
221219.2.70.224/29219.2.70.225 to 219.2.70.230219.2.70.2316
222219.2.70.232/29219.2.70.233 to 219.2.70.238219.2.70.2396
223219.2.70.240/29219.2.70.241 to 219.2.70.246219.2.70.2476
224219.2.70.248/29219.2.70.249 to 219.2.70.254219.2.70.2556
225219.2.71.0/29219.2.71.1 to 219.2.71.6219.2.71.76
226219.2.71.8/29219.2.71.9 to 219.2.71.14219.2.71.156
227219.2.71.16/29219.2.71.17 to 219.2.71.22219.2.71.236
228219.2.71.24/29219.2.71.25 to 219.2.71.30219.2.71.316
229219.2.71.32/29219.2.71.33 to 219.2.71.38219.2.71.396
230219.2.71.40/29219.2.71.41 to 219.2.71.46219.2.71.476
231219.2.71.48/29219.2.71.49 to 219.2.71.54219.2.71.556
232219.2.71.56/29219.2.71.57 to 219.2.71.62219.2.71.636
233219.2.71.64/29219.2.71.65 to 219.2.71.70219.2.71.716
234219.2.71.72/29219.2.71.73 to 219.2.71.78219.2.71.796
235219.2.71.80/29219.2.71.81 to 219.2.71.86219.2.71.876
236219.2.71.88/29219.2.71.89 to 219.2.71.94219.2.71.956
237219.2.71.96/29219.2.71.97 to 219.2.71.102219.2.71.1036
238219.2.71.104/29219.2.71.105 to 219.2.71.110219.2.71.1116
239219.2.71.112/29219.2.71.113 to 219.2.71.118219.2.71.1196
240219.2.71.120/29219.2.71.121 to 219.2.71.126219.2.71.1276
241219.2.71.128/29219.2.71.129 to 219.2.71.134219.2.71.1356
242219.2.71.136/29219.2.71.137 to 219.2.71.142219.2.71.1436
243219.2.71.144/29219.2.71.145 to 219.2.71.150219.2.71.1516
244219.2.71.152/29219.2.71.153 to 219.2.71.158219.2.71.1596
245219.2.71.160/29219.2.71.161 to 219.2.71.166219.2.71.1676
246219.2.71.168/29219.2.71.169 to 219.2.71.174219.2.71.1756
247219.2.71.176/29219.2.71.177 to 219.2.71.182219.2.71.1836
248219.2.71.184/29219.2.71.185 to 219.2.71.190219.2.71.1916
249219.2.71.192/29219.2.71.193 to 219.2.71.198219.2.71.1996
250219.2.71.200/29219.2.71.201 to 219.2.71.206219.2.71.2076
251219.2.71.208/29219.2.71.209 to 219.2.71.214219.2.71.2156
252219.2.71.216/29219.2.71.217 to 219.2.71.222219.2.71.2236
253219.2.71.224/29219.2.71.225 to 219.2.71.230219.2.71.2316
254219.2.71.232/29219.2.71.233 to 219.2.71.238219.2.71.2396
255219.2.71.240/29219.2.71.241 to 219.2.71.246219.2.71.2476
256219.2.71.248/29219.2.71.249 to 219.2.71.254219.2.71.2556

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.