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.

Network234.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
234.0.0.0
Broadcast address
234.127.255.255
First usable
234.0.0.1
Last usable
234.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Multicast 224.0.0.0/4
One-to-many traffic, such as IPTV and routing protocols
Old class
D (multicast)
As numbers
Hex EA000000 · Integer 3925868544 to 3934257151
Reverse DNS zones
0.234.in-addr.arpa
1.234.in-addr.arpa
2.234.in-addr.arpa
3.234.in-addr.arpa
4.234.in-addr.arpa
5.234.in-addr.arpa
6.234.in-addr.arpa
7.234.in-addr.arpa
8.234.in-addr.arpa
9.234.in-addr.arpa
10.234.in-addr.arpa
11.234.in-addr.arpa
12.234.in-addr.arpa
13.234.in-addr.arpa
14.234.in-addr.arpa
15.234.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11101010.00000000.00000000.00000000234.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network11101010.00000000.00000000.00000000234.0.0.0
Broadcast11101010.01111111.11111111.11111111234.127.255.255
Split into smaller subnets/20
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

234.0.0.0/9 makes 2,048 subnets of /20; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1234.0.0.0/20234.0.0.1 to 234.0.15.254234.0.15.2554,094
2234.0.16.0/20234.0.16.1 to 234.0.31.254234.0.31.2554,094
3234.0.32.0/20234.0.32.1 to 234.0.47.254234.0.47.2554,094
4234.0.48.0/20234.0.48.1 to 234.0.63.254234.0.63.2554,094
5234.0.64.0/20234.0.64.1 to 234.0.79.254234.0.79.2554,094
6234.0.80.0/20234.0.80.1 to 234.0.95.254234.0.95.2554,094
7234.0.96.0/20234.0.96.1 to 234.0.111.254234.0.111.2554,094
8234.0.112.0/20234.0.112.1 to 234.0.127.254234.0.127.2554,094
9234.0.128.0/20234.0.128.1 to 234.0.143.254234.0.143.2554,094
10234.0.144.0/20234.0.144.1 to 234.0.159.254234.0.159.2554,094
11234.0.160.0/20234.0.160.1 to 234.0.175.254234.0.175.2554,094
12234.0.176.0/20234.0.176.1 to 234.0.191.254234.0.191.2554,094
13234.0.192.0/20234.0.192.1 to 234.0.207.254234.0.207.2554,094
14234.0.208.0/20234.0.208.1 to 234.0.223.254234.0.223.2554,094
15234.0.224.0/20234.0.224.1 to 234.0.239.254234.0.239.2554,094
16234.0.240.0/20234.0.240.1 to 234.0.255.254234.0.255.2554,094
17234.1.0.0/20234.1.0.1 to 234.1.15.254234.1.15.2554,094
18234.1.16.0/20234.1.16.1 to 234.1.31.254234.1.31.2554,094
19234.1.32.0/20234.1.32.1 to 234.1.47.254234.1.47.2554,094
20234.1.48.0/20234.1.48.1 to 234.1.63.254234.1.63.2554,094
21234.1.64.0/20234.1.64.1 to 234.1.79.254234.1.79.2554,094
22234.1.80.0/20234.1.80.1 to 234.1.95.254234.1.95.2554,094
23234.1.96.0/20234.1.96.1 to 234.1.111.254234.1.111.2554,094
24234.1.112.0/20234.1.112.1 to 234.1.127.254234.1.127.2554,094
25234.1.128.0/20234.1.128.1 to 234.1.143.254234.1.143.2554,094
26234.1.144.0/20234.1.144.1 to 234.1.159.254234.1.159.2554,094
27234.1.160.0/20234.1.160.1 to 234.1.175.254234.1.175.2554,094
28234.1.176.0/20234.1.176.1 to 234.1.191.254234.1.191.2554,094
29234.1.192.0/20234.1.192.1 to 234.1.207.254234.1.207.2554,094
30234.1.208.0/20234.1.208.1 to 234.1.223.254234.1.223.2554,094
31234.1.224.0/20234.1.224.1 to 234.1.239.254234.1.239.2554,094
32234.1.240.0/20234.1.240.1 to 234.1.255.254234.1.255.2554,094
33234.2.0.0/20234.2.0.1 to 234.2.15.254234.2.15.2554,094
34234.2.16.0/20234.2.16.1 to 234.2.31.254234.2.31.2554,094
35234.2.32.0/20234.2.32.1 to 234.2.47.254234.2.47.2554,094
36234.2.48.0/20234.2.48.1 to 234.2.63.254234.2.63.2554,094
37234.2.64.0/20234.2.64.1 to 234.2.79.254234.2.79.2554,094
38234.2.80.0/20234.2.80.1 to 234.2.95.254234.2.95.2554,094
39234.2.96.0/20234.2.96.1 to 234.2.111.254234.2.111.2554,094
40234.2.112.0/20234.2.112.1 to 234.2.127.254234.2.127.2554,094
41234.2.128.0/20234.2.128.1 to 234.2.143.254234.2.143.2554,094
42234.2.144.0/20234.2.144.1 to 234.2.159.254234.2.159.2554,094
43234.2.160.0/20234.2.160.1 to 234.2.175.254234.2.175.2554,094
44234.2.176.0/20234.2.176.1 to 234.2.191.254234.2.191.2554,094
45234.2.192.0/20234.2.192.1 to 234.2.207.254234.2.207.2554,094
46234.2.208.0/20234.2.208.1 to 234.2.223.254234.2.223.2554,094
47234.2.224.0/20234.2.224.1 to 234.2.239.254234.2.239.2554,094
48234.2.240.0/20234.2.240.1 to 234.2.255.254234.2.255.2554,094
49234.3.0.0/20234.3.0.1 to 234.3.15.254234.3.15.2554,094
50234.3.16.0/20234.3.16.1 to 234.3.31.254234.3.31.2554,094
51234.3.32.0/20234.3.32.1 to 234.3.47.254234.3.47.2554,094
52234.3.48.0/20234.3.48.1 to 234.3.63.254234.3.63.2554,094
53234.3.64.0/20234.3.64.1 to 234.3.79.254234.3.79.2554,094
54234.3.80.0/20234.3.80.1 to 234.3.95.254234.3.95.2554,094
55234.3.96.0/20234.3.96.1 to 234.3.111.254234.3.111.2554,094
56234.3.112.0/20234.3.112.1 to 234.3.127.254234.3.127.2554,094
57234.3.128.0/20234.3.128.1 to 234.3.143.254234.3.143.2554,094
58234.3.144.0/20234.3.144.1 to 234.3.159.254234.3.159.2554,094
59234.3.160.0/20234.3.160.1 to 234.3.175.254234.3.175.2554,094
60234.3.176.0/20234.3.176.1 to 234.3.191.254234.3.191.2554,094
61234.3.192.0/20234.3.192.1 to 234.3.207.254234.3.207.2554,094
62234.3.208.0/20234.3.208.1 to 234.3.223.254234.3.223.2554,094
63234.3.224.0/20234.3.224.1 to 234.3.239.254234.3.239.2554,094
64234.3.240.0/20234.3.240.1 to 234.3.255.254234.3.255.2554,094
65234.4.0.0/20234.4.0.1 to 234.4.15.254234.4.15.2554,094
66234.4.16.0/20234.4.16.1 to 234.4.31.254234.4.31.2554,094
67234.4.32.0/20234.4.32.1 to 234.4.47.254234.4.47.2554,094
68234.4.48.0/20234.4.48.1 to 234.4.63.254234.4.63.2554,094
69234.4.64.0/20234.4.64.1 to 234.4.79.254234.4.79.2554,094
70234.4.80.0/20234.4.80.1 to 234.4.95.254234.4.95.2554,094
71234.4.96.0/20234.4.96.1 to 234.4.111.254234.4.111.2554,094
72234.4.112.0/20234.4.112.1 to 234.4.127.254234.4.127.2554,094
73234.4.128.0/20234.4.128.1 to 234.4.143.254234.4.143.2554,094
74234.4.144.0/20234.4.144.1 to 234.4.159.254234.4.159.2554,094
75234.4.160.0/20234.4.160.1 to 234.4.175.254234.4.175.2554,094
76234.4.176.0/20234.4.176.1 to 234.4.191.254234.4.191.2554,094
77234.4.192.0/20234.4.192.1 to 234.4.207.254234.4.207.2554,094
78234.4.208.0/20234.4.208.1 to 234.4.223.254234.4.223.2554,094
79234.4.224.0/20234.4.224.1 to 234.4.239.254234.4.239.2554,094
80234.4.240.0/20234.4.240.1 to 234.4.255.254234.4.255.2554,094
81234.5.0.0/20234.5.0.1 to 234.5.15.254234.5.15.2554,094
82234.5.16.0/20234.5.16.1 to 234.5.31.254234.5.31.2554,094
83234.5.32.0/20234.5.32.1 to 234.5.47.254234.5.47.2554,094
84234.5.48.0/20234.5.48.1 to 234.5.63.254234.5.63.2554,094
85234.5.64.0/20234.5.64.1 to 234.5.79.254234.5.79.2554,094
86234.5.80.0/20234.5.80.1 to 234.5.95.254234.5.95.2554,094
87234.5.96.0/20234.5.96.1 to 234.5.111.254234.5.111.2554,094
88234.5.112.0/20234.5.112.1 to 234.5.127.254234.5.127.2554,094
89234.5.128.0/20234.5.128.1 to 234.5.143.254234.5.143.2554,094
90234.5.144.0/20234.5.144.1 to 234.5.159.254234.5.159.2554,094
91234.5.160.0/20234.5.160.1 to 234.5.175.254234.5.175.2554,094
92234.5.176.0/20234.5.176.1 to 234.5.191.254234.5.191.2554,094
93234.5.192.0/20234.5.192.1 to 234.5.207.254234.5.207.2554,094
94234.5.208.0/20234.5.208.1 to 234.5.223.254234.5.223.2554,094
95234.5.224.0/20234.5.224.1 to 234.5.239.254234.5.239.2554,094
96234.5.240.0/20234.5.240.1 to 234.5.255.254234.5.255.2554,094
97234.6.0.0/20234.6.0.1 to 234.6.15.254234.6.15.2554,094
98234.6.16.0/20234.6.16.1 to 234.6.31.254234.6.31.2554,094
99234.6.32.0/20234.6.32.1 to 234.6.47.254234.6.47.2554,094
100234.6.48.0/20234.6.48.1 to 234.6.63.254234.6.63.2554,094
101234.6.64.0/20234.6.64.1 to 234.6.79.254234.6.79.2554,094
102234.6.80.0/20234.6.80.1 to 234.6.95.254234.6.95.2554,094
103234.6.96.0/20234.6.96.1 to 234.6.111.254234.6.111.2554,094
104234.6.112.0/20234.6.112.1 to 234.6.127.254234.6.127.2554,094
105234.6.128.0/20234.6.128.1 to 234.6.143.254234.6.143.2554,094
106234.6.144.0/20234.6.144.1 to 234.6.159.254234.6.159.2554,094
107234.6.160.0/20234.6.160.1 to 234.6.175.254234.6.175.2554,094
108234.6.176.0/20234.6.176.1 to 234.6.191.254234.6.191.2554,094
109234.6.192.0/20234.6.192.1 to 234.6.207.254234.6.207.2554,094
110234.6.208.0/20234.6.208.1 to 234.6.223.254234.6.223.2554,094
111234.6.224.0/20234.6.224.1 to 234.6.239.254234.6.239.2554,094
112234.6.240.0/20234.6.240.1 to 234.6.255.254234.6.255.2554,094
113234.7.0.0/20234.7.0.1 to 234.7.15.254234.7.15.2554,094
114234.7.16.0/20234.7.16.1 to 234.7.31.254234.7.31.2554,094
115234.7.32.0/20234.7.32.1 to 234.7.47.254234.7.47.2554,094
116234.7.48.0/20234.7.48.1 to 234.7.63.254234.7.63.2554,094
117234.7.64.0/20234.7.64.1 to 234.7.79.254234.7.79.2554,094
118234.7.80.0/20234.7.80.1 to 234.7.95.254234.7.95.2554,094
119234.7.96.0/20234.7.96.1 to 234.7.111.254234.7.111.2554,094
120234.7.112.0/20234.7.112.1 to 234.7.127.254234.7.127.2554,094
121234.7.128.0/20234.7.128.1 to 234.7.143.254234.7.143.2554,094
122234.7.144.0/20234.7.144.1 to 234.7.159.254234.7.159.2554,094
123234.7.160.0/20234.7.160.1 to 234.7.175.254234.7.175.2554,094
124234.7.176.0/20234.7.176.1 to 234.7.191.254234.7.191.2554,094
125234.7.192.0/20234.7.192.1 to 234.7.207.254234.7.207.2554,094
126234.7.208.0/20234.7.208.1 to 234.7.223.254234.7.223.2554,094
127234.7.224.0/20234.7.224.1 to 234.7.239.254234.7.239.2554,094
128234.7.240.0/20234.7.240.1 to 234.7.255.254234.7.255.2554,094
129234.8.0.0/20234.8.0.1 to 234.8.15.254234.8.15.2554,094
130234.8.16.0/20234.8.16.1 to 234.8.31.254234.8.31.2554,094
131234.8.32.0/20234.8.32.1 to 234.8.47.254234.8.47.2554,094
132234.8.48.0/20234.8.48.1 to 234.8.63.254234.8.63.2554,094
133234.8.64.0/20234.8.64.1 to 234.8.79.254234.8.79.2554,094
134234.8.80.0/20234.8.80.1 to 234.8.95.254234.8.95.2554,094
135234.8.96.0/20234.8.96.1 to 234.8.111.254234.8.111.2554,094
136234.8.112.0/20234.8.112.1 to 234.8.127.254234.8.127.2554,094
137234.8.128.0/20234.8.128.1 to 234.8.143.254234.8.143.2554,094
138234.8.144.0/20234.8.144.1 to 234.8.159.254234.8.159.2554,094
139234.8.160.0/20234.8.160.1 to 234.8.175.254234.8.175.2554,094
140234.8.176.0/20234.8.176.1 to 234.8.191.254234.8.191.2554,094
141234.8.192.0/20234.8.192.1 to 234.8.207.254234.8.207.2554,094
142234.8.208.0/20234.8.208.1 to 234.8.223.254234.8.223.2554,094
143234.8.224.0/20234.8.224.1 to 234.8.239.254234.8.239.2554,094
144234.8.240.0/20234.8.240.1 to 234.8.255.254234.8.255.2554,094
145234.9.0.0/20234.9.0.1 to 234.9.15.254234.9.15.2554,094
146234.9.16.0/20234.9.16.1 to 234.9.31.254234.9.31.2554,094
147234.9.32.0/20234.9.32.1 to 234.9.47.254234.9.47.2554,094
148234.9.48.0/20234.9.48.1 to 234.9.63.254234.9.63.2554,094
149234.9.64.0/20234.9.64.1 to 234.9.79.254234.9.79.2554,094
150234.9.80.0/20234.9.80.1 to 234.9.95.254234.9.95.2554,094
151234.9.96.0/20234.9.96.1 to 234.9.111.254234.9.111.2554,094
152234.9.112.0/20234.9.112.1 to 234.9.127.254234.9.127.2554,094
153234.9.128.0/20234.9.128.1 to 234.9.143.254234.9.143.2554,094
154234.9.144.0/20234.9.144.1 to 234.9.159.254234.9.159.2554,094
155234.9.160.0/20234.9.160.1 to 234.9.175.254234.9.175.2554,094
156234.9.176.0/20234.9.176.1 to 234.9.191.254234.9.191.2554,094
157234.9.192.0/20234.9.192.1 to 234.9.207.254234.9.207.2554,094
158234.9.208.0/20234.9.208.1 to 234.9.223.254234.9.223.2554,094
159234.9.224.0/20234.9.224.1 to 234.9.239.254234.9.239.2554,094
160234.9.240.0/20234.9.240.1 to 234.9.255.254234.9.255.2554,094
161234.10.0.0/20234.10.0.1 to 234.10.15.254234.10.15.2554,094
162234.10.16.0/20234.10.16.1 to 234.10.31.254234.10.31.2554,094
163234.10.32.0/20234.10.32.1 to 234.10.47.254234.10.47.2554,094
164234.10.48.0/20234.10.48.1 to 234.10.63.254234.10.63.2554,094
165234.10.64.0/20234.10.64.1 to 234.10.79.254234.10.79.2554,094
166234.10.80.0/20234.10.80.1 to 234.10.95.254234.10.95.2554,094
167234.10.96.0/20234.10.96.1 to 234.10.111.254234.10.111.2554,094
168234.10.112.0/20234.10.112.1 to 234.10.127.254234.10.127.2554,094
169234.10.128.0/20234.10.128.1 to 234.10.143.254234.10.143.2554,094
170234.10.144.0/20234.10.144.1 to 234.10.159.254234.10.159.2554,094
171234.10.160.0/20234.10.160.1 to 234.10.175.254234.10.175.2554,094
172234.10.176.0/20234.10.176.1 to 234.10.191.254234.10.191.2554,094
173234.10.192.0/20234.10.192.1 to 234.10.207.254234.10.207.2554,094
174234.10.208.0/20234.10.208.1 to 234.10.223.254234.10.223.2554,094
175234.10.224.0/20234.10.224.1 to 234.10.239.254234.10.239.2554,094
176234.10.240.0/20234.10.240.1 to 234.10.255.254234.10.255.2554,094
177234.11.0.0/20234.11.0.1 to 234.11.15.254234.11.15.2554,094
178234.11.16.0/20234.11.16.1 to 234.11.31.254234.11.31.2554,094
179234.11.32.0/20234.11.32.1 to 234.11.47.254234.11.47.2554,094
180234.11.48.0/20234.11.48.1 to 234.11.63.254234.11.63.2554,094
181234.11.64.0/20234.11.64.1 to 234.11.79.254234.11.79.2554,094
182234.11.80.0/20234.11.80.1 to 234.11.95.254234.11.95.2554,094
183234.11.96.0/20234.11.96.1 to 234.11.111.254234.11.111.2554,094
184234.11.112.0/20234.11.112.1 to 234.11.127.254234.11.127.2554,094
185234.11.128.0/20234.11.128.1 to 234.11.143.254234.11.143.2554,094
186234.11.144.0/20234.11.144.1 to 234.11.159.254234.11.159.2554,094
187234.11.160.0/20234.11.160.1 to 234.11.175.254234.11.175.2554,094
188234.11.176.0/20234.11.176.1 to 234.11.191.254234.11.191.2554,094
189234.11.192.0/20234.11.192.1 to 234.11.207.254234.11.207.2554,094
190234.11.208.0/20234.11.208.1 to 234.11.223.254234.11.223.2554,094
191234.11.224.0/20234.11.224.1 to 234.11.239.254234.11.239.2554,094
192234.11.240.0/20234.11.240.1 to 234.11.255.254234.11.255.2554,094
193234.12.0.0/20234.12.0.1 to 234.12.15.254234.12.15.2554,094
194234.12.16.0/20234.12.16.1 to 234.12.31.254234.12.31.2554,094
195234.12.32.0/20234.12.32.1 to 234.12.47.254234.12.47.2554,094
196234.12.48.0/20234.12.48.1 to 234.12.63.254234.12.63.2554,094
197234.12.64.0/20234.12.64.1 to 234.12.79.254234.12.79.2554,094
198234.12.80.0/20234.12.80.1 to 234.12.95.254234.12.95.2554,094
199234.12.96.0/20234.12.96.1 to 234.12.111.254234.12.111.2554,094
200234.12.112.0/20234.12.112.1 to 234.12.127.254234.12.127.2554,094
201234.12.128.0/20234.12.128.1 to 234.12.143.254234.12.143.2554,094
202234.12.144.0/20234.12.144.1 to 234.12.159.254234.12.159.2554,094
203234.12.160.0/20234.12.160.1 to 234.12.175.254234.12.175.2554,094
204234.12.176.0/20234.12.176.1 to 234.12.191.254234.12.191.2554,094
205234.12.192.0/20234.12.192.1 to 234.12.207.254234.12.207.2554,094
206234.12.208.0/20234.12.208.1 to 234.12.223.254234.12.223.2554,094
207234.12.224.0/20234.12.224.1 to 234.12.239.254234.12.239.2554,094
208234.12.240.0/20234.12.240.1 to 234.12.255.254234.12.255.2554,094
209234.13.0.0/20234.13.0.1 to 234.13.15.254234.13.15.2554,094
210234.13.16.0/20234.13.16.1 to 234.13.31.254234.13.31.2554,094
211234.13.32.0/20234.13.32.1 to 234.13.47.254234.13.47.2554,094
212234.13.48.0/20234.13.48.1 to 234.13.63.254234.13.63.2554,094
213234.13.64.0/20234.13.64.1 to 234.13.79.254234.13.79.2554,094
214234.13.80.0/20234.13.80.1 to 234.13.95.254234.13.95.2554,094
215234.13.96.0/20234.13.96.1 to 234.13.111.254234.13.111.2554,094
216234.13.112.0/20234.13.112.1 to 234.13.127.254234.13.127.2554,094
217234.13.128.0/20234.13.128.1 to 234.13.143.254234.13.143.2554,094
218234.13.144.0/20234.13.144.1 to 234.13.159.254234.13.159.2554,094
219234.13.160.0/20234.13.160.1 to 234.13.175.254234.13.175.2554,094
220234.13.176.0/20234.13.176.1 to 234.13.191.254234.13.191.2554,094
221234.13.192.0/20234.13.192.1 to 234.13.207.254234.13.207.2554,094
222234.13.208.0/20234.13.208.1 to 234.13.223.254234.13.223.2554,094
223234.13.224.0/20234.13.224.1 to 234.13.239.254234.13.239.2554,094
224234.13.240.0/20234.13.240.1 to 234.13.255.254234.13.255.2554,094
225234.14.0.0/20234.14.0.1 to 234.14.15.254234.14.15.2554,094
226234.14.16.0/20234.14.16.1 to 234.14.31.254234.14.31.2554,094
227234.14.32.0/20234.14.32.1 to 234.14.47.254234.14.47.2554,094
228234.14.48.0/20234.14.48.1 to 234.14.63.254234.14.63.2554,094
229234.14.64.0/20234.14.64.1 to 234.14.79.254234.14.79.2554,094
230234.14.80.0/20234.14.80.1 to 234.14.95.254234.14.95.2554,094
231234.14.96.0/20234.14.96.1 to 234.14.111.254234.14.111.2554,094
232234.14.112.0/20234.14.112.1 to 234.14.127.254234.14.127.2554,094
233234.14.128.0/20234.14.128.1 to 234.14.143.254234.14.143.2554,094
234234.14.144.0/20234.14.144.1 to 234.14.159.254234.14.159.2554,094
235234.14.160.0/20234.14.160.1 to 234.14.175.254234.14.175.2554,094
236234.14.176.0/20234.14.176.1 to 234.14.191.254234.14.191.2554,094
237234.14.192.0/20234.14.192.1 to 234.14.207.254234.14.207.2554,094
238234.14.208.0/20234.14.208.1 to 234.14.223.254234.14.223.2554,094
239234.14.224.0/20234.14.224.1 to 234.14.239.254234.14.239.2554,094
240234.14.240.0/20234.14.240.1 to 234.14.255.254234.14.255.2554,094
241234.15.0.0/20234.15.0.1 to 234.15.15.254234.15.15.2554,094
242234.15.16.0/20234.15.16.1 to 234.15.31.254234.15.31.2554,094
243234.15.32.0/20234.15.32.1 to 234.15.47.254234.15.47.2554,094
244234.15.48.0/20234.15.48.1 to 234.15.63.254234.15.63.2554,094
245234.15.64.0/20234.15.64.1 to 234.15.79.254234.15.79.2554,094
246234.15.80.0/20234.15.80.1 to 234.15.95.254234.15.95.2554,094
247234.15.96.0/20234.15.96.1 to 234.15.111.254234.15.111.2554,094
248234.15.112.0/20234.15.112.1 to 234.15.127.254234.15.127.2554,094
249234.15.128.0/20234.15.128.1 to 234.15.143.254234.15.143.2554,094
250234.15.144.0/20234.15.144.1 to 234.15.159.254234.15.159.2554,094
251234.15.160.0/20234.15.160.1 to 234.15.175.254234.15.175.2554,094
252234.15.176.0/20234.15.176.1 to 234.15.191.254234.15.191.2554,094
253234.15.192.0/20234.15.192.1 to 234.15.207.254234.15.207.2554,094
254234.15.208.0/20234.15.208.1 to 234.15.223.254234.15.223.2554,094
255234.15.224.0/20234.15.224.1 to 234.15.239.254234.15.239.2554,094
256234.15.240.0/20234.15.240.1 to 234.15.255.254234.15.255.2554,094

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.