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.

Network117.128.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
117.128.0.0
Broadcast address
117.255.255.255
First usable
117.128.0.1
Last usable
117.255.255.254
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
Public public
Old class
A (default /8)
As numbers
Hex 75800000 · Integer 1971322880 to 1979711487
Reverse DNS zones
128.117.in-addr.arpa
129.117.in-addr.arpa
130.117.in-addr.arpa
131.117.in-addr.arpa
132.117.in-addr.arpa
133.117.in-addr.arpa
134.117.in-addr.arpa
135.117.in-addr.arpa
136.117.in-addr.arpa
137.117.in-addr.arpa
138.117.in-addr.arpa
139.117.in-addr.arpa
140.117.in-addr.arpa
141.117.in-addr.arpa
142.117.in-addr.arpa
143.117.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
Address01110101.10000000.00000000.00000000117.128.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01110101.10000000.00000000.00000000117.128.0.0
Broadcast01110101.11111111.11111111.11111111117.255.255.255
Split into smaller subnets/21
/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)

117.128.0.0/9 makes 4,096 subnets of /21; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1117.128.0.0/21117.128.0.1 to 117.128.7.254117.128.7.2552,046
2117.128.8.0/21117.128.8.1 to 117.128.15.254117.128.15.2552,046
3117.128.16.0/21117.128.16.1 to 117.128.23.254117.128.23.2552,046
4117.128.24.0/21117.128.24.1 to 117.128.31.254117.128.31.2552,046
5117.128.32.0/21117.128.32.1 to 117.128.39.254117.128.39.2552,046
6117.128.40.0/21117.128.40.1 to 117.128.47.254117.128.47.2552,046
7117.128.48.0/21117.128.48.1 to 117.128.55.254117.128.55.2552,046
8117.128.56.0/21117.128.56.1 to 117.128.63.254117.128.63.2552,046
9117.128.64.0/21117.128.64.1 to 117.128.71.254117.128.71.2552,046
10117.128.72.0/21117.128.72.1 to 117.128.79.254117.128.79.2552,046
11117.128.80.0/21117.128.80.1 to 117.128.87.254117.128.87.2552,046
12117.128.88.0/21117.128.88.1 to 117.128.95.254117.128.95.2552,046
13117.128.96.0/21117.128.96.1 to 117.128.103.254117.128.103.2552,046
14117.128.104.0/21117.128.104.1 to 117.128.111.254117.128.111.2552,046
15117.128.112.0/21117.128.112.1 to 117.128.119.254117.128.119.2552,046
16117.128.120.0/21117.128.120.1 to 117.128.127.254117.128.127.2552,046
17117.128.128.0/21117.128.128.1 to 117.128.135.254117.128.135.2552,046
18117.128.136.0/21117.128.136.1 to 117.128.143.254117.128.143.2552,046
19117.128.144.0/21117.128.144.1 to 117.128.151.254117.128.151.2552,046
20117.128.152.0/21117.128.152.1 to 117.128.159.254117.128.159.2552,046
21117.128.160.0/21117.128.160.1 to 117.128.167.254117.128.167.2552,046
22117.128.168.0/21117.128.168.1 to 117.128.175.254117.128.175.2552,046
23117.128.176.0/21117.128.176.1 to 117.128.183.254117.128.183.2552,046
24117.128.184.0/21117.128.184.1 to 117.128.191.254117.128.191.2552,046
25117.128.192.0/21117.128.192.1 to 117.128.199.254117.128.199.2552,046
26117.128.200.0/21117.128.200.1 to 117.128.207.254117.128.207.2552,046
27117.128.208.0/21117.128.208.1 to 117.128.215.254117.128.215.2552,046
28117.128.216.0/21117.128.216.1 to 117.128.223.254117.128.223.2552,046
29117.128.224.0/21117.128.224.1 to 117.128.231.254117.128.231.2552,046
30117.128.232.0/21117.128.232.1 to 117.128.239.254117.128.239.2552,046
31117.128.240.0/21117.128.240.1 to 117.128.247.254117.128.247.2552,046
32117.128.248.0/21117.128.248.1 to 117.128.255.254117.128.255.2552,046
33117.129.0.0/21117.129.0.1 to 117.129.7.254117.129.7.2552,046
34117.129.8.0/21117.129.8.1 to 117.129.15.254117.129.15.2552,046
35117.129.16.0/21117.129.16.1 to 117.129.23.254117.129.23.2552,046
36117.129.24.0/21117.129.24.1 to 117.129.31.254117.129.31.2552,046
37117.129.32.0/21117.129.32.1 to 117.129.39.254117.129.39.2552,046
38117.129.40.0/21117.129.40.1 to 117.129.47.254117.129.47.2552,046
39117.129.48.0/21117.129.48.1 to 117.129.55.254117.129.55.2552,046
40117.129.56.0/21117.129.56.1 to 117.129.63.254117.129.63.2552,046
41117.129.64.0/21117.129.64.1 to 117.129.71.254117.129.71.2552,046
42117.129.72.0/21117.129.72.1 to 117.129.79.254117.129.79.2552,046
43117.129.80.0/21117.129.80.1 to 117.129.87.254117.129.87.2552,046
44117.129.88.0/21117.129.88.1 to 117.129.95.254117.129.95.2552,046
45117.129.96.0/21117.129.96.1 to 117.129.103.254117.129.103.2552,046
46117.129.104.0/21117.129.104.1 to 117.129.111.254117.129.111.2552,046
47117.129.112.0/21117.129.112.1 to 117.129.119.254117.129.119.2552,046
48117.129.120.0/21117.129.120.1 to 117.129.127.254117.129.127.2552,046
49117.129.128.0/21117.129.128.1 to 117.129.135.254117.129.135.2552,046
50117.129.136.0/21117.129.136.1 to 117.129.143.254117.129.143.2552,046
51117.129.144.0/21117.129.144.1 to 117.129.151.254117.129.151.2552,046
52117.129.152.0/21117.129.152.1 to 117.129.159.254117.129.159.2552,046
53117.129.160.0/21117.129.160.1 to 117.129.167.254117.129.167.2552,046
54117.129.168.0/21117.129.168.1 to 117.129.175.254117.129.175.2552,046
55117.129.176.0/21117.129.176.1 to 117.129.183.254117.129.183.2552,046
56117.129.184.0/21117.129.184.1 to 117.129.191.254117.129.191.2552,046
57117.129.192.0/21117.129.192.1 to 117.129.199.254117.129.199.2552,046
58117.129.200.0/21117.129.200.1 to 117.129.207.254117.129.207.2552,046
59117.129.208.0/21117.129.208.1 to 117.129.215.254117.129.215.2552,046
60117.129.216.0/21117.129.216.1 to 117.129.223.254117.129.223.2552,046
61117.129.224.0/21117.129.224.1 to 117.129.231.254117.129.231.2552,046
62117.129.232.0/21117.129.232.1 to 117.129.239.254117.129.239.2552,046
63117.129.240.0/21117.129.240.1 to 117.129.247.254117.129.247.2552,046
64117.129.248.0/21117.129.248.1 to 117.129.255.254117.129.255.2552,046
65117.130.0.0/21117.130.0.1 to 117.130.7.254117.130.7.2552,046
66117.130.8.0/21117.130.8.1 to 117.130.15.254117.130.15.2552,046
67117.130.16.0/21117.130.16.1 to 117.130.23.254117.130.23.2552,046
68117.130.24.0/21117.130.24.1 to 117.130.31.254117.130.31.2552,046
69117.130.32.0/21117.130.32.1 to 117.130.39.254117.130.39.2552,046
70117.130.40.0/21117.130.40.1 to 117.130.47.254117.130.47.2552,046
71117.130.48.0/21117.130.48.1 to 117.130.55.254117.130.55.2552,046
72117.130.56.0/21117.130.56.1 to 117.130.63.254117.130.63.2552,046
73117.130.64.0/21117.130.64.1 to 117.130.71.254117.130.71.2552,046
74117.130.72.0/21117.130.72.1 to 117.130.79.254117.130.79.2552,046
75117.130.80.0/21117.130.80.1 to 117.130.87.254117.130.87.2552,046
76117.130.88.0/21117.130.88.1 to 117.130.95.254117.130.95.2552,046
77117.130.96.0/21117.130.96.1 to 117.130.103.254117.130.103.2552,046
78117.130.104.0/21117.130.104.1 to 117.130.111.254117.130.111.2552,046
79117.130.112.0/21117.130.112.1 to 117.130.119.254117.130.119.2552,046
80117.130.120.0/21117.130.120.1 to 117.130.127.254117.130.127.2552,046
81117.130.128.0/21117.130.128.1 to 117.130.135.254117.130.135.2552,046
82117.130.136.0/21117.130.136.1 to 117.130.143.254117.130.143.2552,046
83117.130.144.0/21117.130.144.1 to 117.130.151.254117.130.151.2552,046
84117.130.152.0/21117.130.152.1 to 117.130.159.254117.130.159.2552,046
85117.130.160.0/21117.130.160.1 to 117.130.167.254117.130.167.2552,046
86117.130.168.0/21117.130.168.1 to 117.130.175.254117.130.175.2552,046
87117.130.176.0/21117.130.176.1 to 117.130.183.254117.130.183.2552,046
88117.130.184.0/21117.130.184.1 to 117.130.191.254117.130.191.2552,046
89117.130.192.0/21117.130.192.1 to 117.130.199.254117.130.199.2552,046
90117.130.200.0/21117.130.200.1 to 117.130.207.254117.130.207.2552,046
91117.130.208.0/21117.130.208.1 to 117.130.215.254117.130.215.2552,046
92117.130.216.0/21117.130.216.1 to 117.130.223.254117.130.223.2552,046
93117.130.224.0/21117.130.224.1 to 117.130.231.254117.130.231.2552,046
94117.130.232.0/21117.130.232.1 to 117.130.239.254117.130.239.2552,046
95117.130.240.0/21117.130.240.1 to 117.130.247.254117.130.247.2552,046
96117.130.248.0/21117.130.248.1 to 117.130.255.254117.130.255.2552,046
97117.131.0.0/21117.131.0.1 to 117.131.7.254117.131.7.2552,046
98117.131.8.0/21117.131.8.1 to 117.131.15.254117.131.15.2552,046
99117.131.16.0/21117.131.16.1 to 117.131.23.254117.131.23.2552,046
100117.131.24.0/21117.131.24.1 to 117.131.31.254117.131.31.2552,046
101117.131.32.0/21117.131.32.1 to 117.131.39.254117.131.39.2552,046
102117.131.40.0/21117.131.40.1 to 117.131.47.254117.131.47.2552,046
103117.131.48.0/21117.131.48.1 to 117.131.55.254117.131.55.2552,046
104117.131.56.0/21117.131.56.1 to 117.131.63.254117.131.63.2552,046
105117.131.64.0/21117.131.64.1 to 117.131.71.254117.131.71.2552,046
106117.131.72.0/21117.131.72.1 to 117.131.79.254117.131.79.2552,046
107117.131.80.0/21117.131.80.1 to 117.131.87.254117.131.87.2552,046
108117.131.88.0/21117.131.88.1 to 117.131.95.254117.131.95.2552,046
109117.131.96.0/21117.131.96.1 to 117.131.103.254117.131.103.2552,046
110117.131.104.0/21117.131.104.1 to 117.131.111.254117.131.111.2552,046
111117.131.112.0/21117.131.112.1 to 117.131.119.254117.131.119.2552,046
112117.131.120.0/21117.131.120.1 to 117.131.127.254117.131.127.2552,046
113117.131.128.0/21117.131.128.1 to 117.131.135.254117.131.135.2552,046
114117.131.136.0/21117.131.136.1 to 117.131.143.254117.131.143.2552,046
115117.131.144.0/21117.131.144.1 to 117.131.151.254117.131.151.2552,046
116117.131.152.0/21117.131.152.1 to 117.131.159.254117.131.159.2552,046
117117.131.160.0/21117.131.160.1 to 117.131.167.254117.131.167.2552,046
118117.131.168.0/21117.131.168.1 to 117.131.175.254117.131.175.2552,046
119117.131.176.0/21117.131.176.1 to 117.131.183.254117.131.183.2552,046
120117.131.184.0/21117.131.184.1 to 117.131.191.254117.131.191.2552,046
121117.131.192.0/21117.131.192.1 to 117.131.199.254117.131.199.2552,046
122117.131.200.0/21117.131.200.1 to 117.131.207.254117.131.207.2552,046
123117.131.208.0/21117.131.208.1 to 117.131.215.254117.131.215.2552,046
124117.131.216.0/21117.131.216.1 to 117.131.223.254117.131.223.2552,046
125117.131.224.0/21117.131.224.1 to 117.131.231.254117.131.231.2552,046
126117.131.232.0/21117.131.232.1 to 117.131.239.254117.131.239.2552,046
127117.131.240.0/21117.131.240.1 to 117.131.247.254117.131.247.2552,046
128117.131.248.0/21117.131.248.1 to 117.131.255.254117.131.255.2552,046
129117.132.0.0/21117.132.0.1 to 117.132.7.254117.132.7.2552,046
130117.132.8.0/21117.132.8.1 to 117.132.15.254117.132.15.2552,046
131117.132.16.0/21117.132.16.1 to 117.132.23.254117.132.23.2552,046
132117.132.24.0/21117.132.24.1 to 117.132.31.254117.132.31.2552,046
133117.132.32.0/21117.132.32.1 to 117.132.39.254117.132.39.2552,046
134117.132.40.0/21117.132.40.1 to 117.132.47.254117.132.47.2552,046
135117.132.48.0/21117.132.48.1 to 117.132.55.254117.132.55.2552,046
136117.132.56.0/21117.132.56.1 to 117.132.63.254117.132.63.2552,046
137117.132.64.0/21117.132.64.1 to 117.132.71.254117.132.71.2552,046
138117.132.72.0/21117.132.72.1 to 117.132.79.254117.132.79.2552,046
139117.132.80.0/21117.132.80.1 to 117.132.87.254117.132.87.2552,046
140117.132.88.0/21117.132.88.1 to 117.132.95.254117.132.95.2552,046
141117.132.96.0/21117.132.96.1 to 117.132.103.254117.132.103.2552,046
142117.132.104.0/21117.132.104.1 to 117.132.111.254117.132.111.2552,046
143117.132.112.0/21117.132.112.1 to 117.132.119.254117.132.119.2552,046
144117.132.120.0/21117.132.120.1 to 117.132.127.254117.132.127.2552,046
145117.132.128.0/21117.132.128.1 to 117.132.135.254117.132.135.2552,046
146117.132.136.0/21117.132.136.1 to 117.132.143.254117.132.143.2552,046
147117.132.144.0/21117.132.144.1 to 117.132.151.254117.132.151.2552,046
148117.132.152.0/21117.132.152.1 to 117.132.159.254117.132.159.2552,046
149117.132.160.0/21117.132.160.1 to 117.132.167.254117.132.167.2552,046
150117.132.168.0/21117.132.168.1 to 117.132.175.254117.132.175.2552,046
151117.132.176.0/21117.132.176.1 to 117.132.183.254117.132.183.2552,046
152117.132.184.0/21117.132.184.1 to 117.132.191.254117.132.191.2552,046
153117.132.192.0/21117.132.192.1 to 117.132.199.254117.132.199.2552,046
154117.132.200.0/21117.132.200.1 to 117.132.207.254117.132.207.2552,046
155117.132.208.0/21117.132.208.1 to 117.132.215.254117.132.215.2552,046
156117.132.216.0/21117.132.216.1 to 117.132.223.254117.132.223.2552,046
157117.132.224.0/21117.132.224.1 to 117.132.231.254117.132.231.2552,046
158117.132.232.0/21117.132.232.1 to 117.132.239.254117.132.239.2552,046
159117.132.240.0/21117.132.240.1 to 117.132.247.254117.132.247.2552,046
160117.132.248.0/21117.132.248.1 to 117.132.255.254117.132.255.2552,046
161117.133.0.0/21117.133.0.1 to 117.133.7.254117.133.7.2552,046
162117.133.8.0/21117.133.8.1 to 117.133.15.254117.133.15.2552,046
163117.133.16.0/21117.133.16.1 to 117.133.23.254117.133.23.2552,046
164117.133.24.0/21117.133.24.1 to 117.133.31.254117.133.31.2552,046
165117.133.32.0/21117.133.32.1 to 117.133.39.254117.133.39.2552,046
166117.133.40.0/21117.133.40.1 to 117.133.47.254117.133.47.2552,046
167117.133.48.0/21117.133.48.1 to 117.133.55.254117.133.55.2552,046
168117.133.56.0/21117.133.56.1 to 117.133.63.254117.133.63.2552,046
169117.133.64.0/21117.133.64.1 to 117.133.71.254117.133.71.2552,046
170117.133.72.0/21117.133.72.1 to 117.133.79.254117.133.79.2552,046
171117.133.80.0/21117.133.80.1 to 117.133.87.254117.133.87.2552,046
172117.133.88.0/21117.133.88.1 to 117.133.95.254117.133.95.2552,046
173117.133.96.0/21117.133.96.1 to 117.133.103.254117.133.103.2552,046
174117.133.104.0/21117.133.104.1 to 117.133.111.254117.133.111.2552,046
175117.133.112.0/21117.133.112.1 to 117.133.119.254117.133.119.2552,046
176117.133.120.0/21117.133.120.1 to 117.133.127.254117.133.127.2552,046
177117.133.128.0/21117.133.128.1 to 117.133.135.254117.133.135.2552,046
178117.133.136.0/21117.133.136.1 to 117.133.143.254117.133.143.2552,046
179117.133.144.0/21117.133.144.1 to 117.133.151.254117.133.151.2552,046
180117.133.152.0/21117.133.152.1 to 117.133.159.254117.133.159.2552,046
181117.133.160.0/21117.133.160.1 to 117.133.167.254117.133.167.2552,046
182117.133.168.0/21117.133.168.1 to 117.133.175.254117.133.175.2552,046
183117.133.176.0/21117.133.176.1 to 117.133.183.254117.133.183.2552,046
184117.133.184.0/21117.133.184.1 to 117.133.191.254117.133.191.2552,046
185117.133.192.0/21117.133.192.1 to 117.133.199.254117.133.199.2552,046
186117.133.200.0/21117.133.200.1 to 117.133.207.254117.133.207.2552,046
187117.133.208.0/21117.133.208.1 to 117.133.215.254117.133.215.2552,046
188117.133.216.0/21117.133.216.1 to 117.133.223.254117.133.223.2552,046
189117.133.224.0/21117.133.224.1 to 117.133.231.254117.133.231.2552,046
190117.133.232.0/21117.133.232.1 to 117.133.239.254117.133.239.2552,046
191117.133.240.0/21117.133.240.1 to 117.133.247.254117.133.247.2552,046
192117.133.248.0/21117.133.248.1 to 117.133.255.254117.133.255.2552,046
193117.134.0.0/21117.134.0.1 to 117.134.7.254117.134.7.2552,046
194117.134.8.0/21117.134.8.1 to 117.134.15.254117.134.15.2552,046
195117.134.16.0/21117.134.16.1 to 117.134.23.254117.134.23.2552,046
196117.134.24.0/21117.134.24.1 to 117.134.31.254117.134.31.2552,046
197117.134.32.0/21117.134.32.1 to 117.134.39.254117.134.39.2552,046
198117.134.40.0/21117.134.40.1 to 117.134.47.254117.134.47.2552,046
199117.134.48.0/21117.134.48.1 to 117.134.55.254117.134.55.2552,046
200117.134.56.0/21117.134.56.1 to 117.134.63.254117.134.63.2552,046
201117.134.64.0/21117.134.64.1 to 117.134.71.254117.134.71.2552,046
202117.134.72.0/21117.134.72.1 to 117.134.79.254117.134.79.2552,046
203117.134.80.0/21117.134.80.1 to 117.134.87.254117.134.87.2552,046
204117.134.88.0/21117.134.88.1 to 117.134.95.254117.134.95.2552,046
205117.134.96.0/21117.134.96.1 to 117.134.103.254117.134.103.2552,046
206117.134.104.0/21117.134.104.1 to 117.134.111.254117.134.111.2552,046
207117.134.112.0/21117.134.112.1 to 117.134.119.254117.134.119.2552,046
208117.134.120.0/21117.134.120.1 to 117.134.127.254117.134.127.2552,046
209117.134.128.0/21117.134.128.1 to 117.134.135.254117.134.135.2552,046
210117.134.136.0/21117.134.136.1 to 117.134.143.254117.134.143.2552,046
211117.134.144.0/21117.134.144.1 to 117.134.151.254117.134.151.2552,046
212117.134.152.0/21117.134.152.1 to 117.134.159.254117.134.159.2552,046
213117.134.160.0/21117.134.160.1 to 117.134.167.254117.134.167.2552,046
214117.134.168.0/21117.134.168.1 to 117.134.175.254117.134.175.2552,046
215117.134.176.0/21117.134.176.1 to 117.134.183.254117.134.183.2552,046
216117.134.184.0/21117.134.184.1 to 117.134.191.254117.134.191.2552,046
217117.134.192.0/21117.134.192.1 to 117.134.199.254117.134.199.2552,046
218117.134.200.0/21117.134.200.1 to 117.134.207.254117.134.207.2552,046
219117.134.208.0/21117.134.208.1 to 117.134.215.254117.134.215.2552,046
220117.134.216.0/21117.134.216.1 to 117.134.223.254117.134.223.2552,046
221117.134.224.0/21117.134.224.1 to 117.134.231.254117.134.231.2552,046
222117.134.232.0/21117.134.232.1 to 117.134.239.254117.134.239.2552,046
223117.134.240.0/21117.134.240.1 to 117.134.247.254117.134.247.2552,046
224117.134.248.0/21117.134.248.1 to 117.134.255.254117.134.255.2552,046
225117.135.0.0/21117.135.0.1 to 117.135.7.254117.135.7.2552,046
226117.135.8.0/21117.135.8.1 to 117.135.15.254117.135.15.2552,046
227117.135.16.0/21117.135.16.1 to 117.135.23.254117.135.23.2552,046
228117.135.24.0/21117.135.24.1 to 117.135.31.254117.135.31.2552,046
229117.135.32.0/21117.135.32.1 to 117.135.39.254117.135.39.2552,046
230117.135.40.0/21117.135.40.1 to 117.135.47.254117.135.47.2552,046
231117.135.48.0/21117.135.48.1 to 117.135.55.254117.135.55.2552,046
232117.135.56.0/21117.135.56.1 to 117.135.63.254117.135.63.2552,046
233117.135.64.0/21117.135.64.1 to 117.135.71.254117.135.71.2552,046
234117.135.72.0/21117.135.72.1 to 117.135.79.254117.135.79.2552,046
235117.135.80.0/21117.135.80.1 to 117.135.87.254117.135.87.2552,046
236117.135.88.0/21117.135.88.1 to 117.135.95.254117.135.95.2552,046
237117.135.96.0/21117.135.96.1 to 117.135.103.254117.135.103.2552,046
238117.135.104.0/21117.135.104.1 to 117.135.111.254117.135.111.2552,046
239117.135.112.0/21117.135.112.1 to 117.135.119.254117.135.119.2552,046
240117.135.120.0/21117.135.120.1 to 117.135.127.254117.135.127.2552,046
241117.135.128.0/21117.135.128.1 to 117.135.135.254117.135.135.2552,046
242117.135.136.0/21117.135.136.1 to 117.135.143.254117.135.143.2552,046
243117.135.144.0/21117.135.144.1 to 117.135.151.254117.135.151.2552,046
244117.135.152.0/21117.135.152.1 to 117.135.159.254117.135.159.2552,046
245117.135.160.0/21117.135.160.1 to 117.135.167.254117.135.167.2552,046
246117.135.168.0/21117.135.168.1 to 117.135.175.254117.135.175.2552,046
247117.135.176.0/21117.135.176.1 to 117.135.183.254117.135.183.2552,046
248117.135.184.0/21117.135.184.1 to 117.135.191.254117.135.191.2552,046
249117.135.192.0/21117.135.192.1 to 117.135.199.254117.135.199.2552,046
250117.135.200.0/21117.135.200.1 to 117.135.207.254117.135.207.2552,046
251117.135.208.0/21117.135.208.1 to 117.135.215.254117.135.215.2552,046
252117.135.216.0/21117.135.216.1 to 117.135.223.254117.135.223.2552,046
253117.135.224.0/21117.135.224.1 to 117.135.231.254117.135.231.2552,046
254117.135.232.0/21117.135.232.1 to 117.135.239.254117.135.239.2552,046
255117.135.240.0/21117.135.240.1 to 117.135.247.254117.135.247.2552,046
256117.135.248.0/21117.135.248.1 to 117.135.255.254117.135.255.2552,046

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.