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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.

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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/24
Addresses2^104
/64 networks2^40
Network
ffcb:dd00::/24
First address
ffcb:dd00::
Last address
ffcb:ddff:ffff:ffff:ffff:ffff:ffff:ffff
Addresses
20,282,409,603,651,670,423,947,251,286,016 (2^104)
/64 networks (LANs)
1,099,511,627,776 (2^40)
Full form
ffcb:dd00:0000:0000:0000:0000:0000:0000
Type
Multicast ff00::/8
One-to-many traffic; replaces broadcast
Reverse DNS zone
d.d.b.c.f.f.ip6.arpa
Split into smaller subnets/32
/25 (2)/26 (4)/27 (8)/28 (16)/32 (256)/36 (4,096)/40 (65,536)

ffcb:dd00::/24 makes 256 subnets of /32.

Subnets
#SubnetLast address
1ffcb:dd00::/32ffcb:dd00:ffff:ffff:ffff:ffff:ffff:ffff
2ffcb:dd01::/32ffcb:dd01:ffff:ffff:ffff:ffff:ffff:ffff
3ffcb:dd02::/32ffcb:dd02:ffff:ffff:ffff:ffff:ffff:ffff
4ffcb:dd03::/32ffcb:dd03:ffff:ffff:ffff:ffff:ffff:ffff
5ffcb:dd04::/32ffcb:dd04:ffff:ffff:ffff:ffff:ffff:ffff
6ffcb:dd05::/32ffcb:dd05:ffff:ffff:ffff:ffff:ffff:ffff
7ffcb:dd06::/32ffcb:dd06:ffff:ffff:ffff:ffff:ffff:ffff
8ffcb:dd07::/32ffcb:dd07:ffff:ffff:ffff:ffff:ffff:ffff
9ffcb:dd08::/32ffcb:dd08:ffff:ffff:ffff:ffff:ffff:ffff
10ffcb:dd09::/32ffcb:dd09:ffff:ffff:ffff:ffff:ffff:ffff
11ffcb:dd0a::/32ffcb:dd0a:ffff:ffff:ffff:ffff:ffff:ffff
12ffcb:dd0b::/32ffcb:dd0b:ffff:ffff:ffff:ffff:ffff:ffff
13ffcb:dd0c::/32ffcb:dd0c:ffff:ffff:ffff:ffff:ffff:ffff
14ffcb:dd0d::/32ffcb:dd0d:ffff:ffff:ffff:ffff:ffff:ffff
15ffcb:dd0e::/32ffcb:dd0e:ffff:ffff:ffff:ffff:ffff:ffff
16ffcb:dd0f::/32ffcb:dd0f:ffff:ffff:ffff:ffff:ffff:ffff
17ffcb:dd10::/32ffcb:dd10:ffff:ffff:ffff:ffff:ffff:ffff
18ffcb:dd11::/32ffcb:dd11:ffff:ffff:ffff:ffff:ffff:ffff
19ffcb:dd12::/32ffcb:dd12:ffff:ffff:ffff:ffff:ffff:ffff
20ffcb:dd13::/32ffcb:dd13:ffff:ffff:ffff:ffff:ffff:ffff
21ffcb:dd14::/32ffcb:dd14:ffff:ffff:ffff:ffff:ffff:ffff
22ffcb:dd15::/32ffcb:dd15:ffff:ffff:ffff:ffff:ffff:ffff
23ffcb:dd16::/32ffcb:dd16:ffff:ffff:ffff:ffff:ffff:ffff
24ffcb:dd17::/32ffcb:dd17:ffff:ffff:ffff:ffff:ffff:ffff
25ffcb:dd18::/32ffcb:dd18:ffff:ffff:ffff:ffff:ffff:ffff
26ffcb:dd19::/32ffcb:dd19:ffff:ffff:ffff:ffff:ffff:ffff
27ffcb:dd1a::/32ffcb:dd1a:ffff:ffff:ffff:ffff:ffff:ffff
28ffcb:dd1b::/32ffcb:dd1b:ffff:ffff:ffff:ffff:ffff:ffff
29ffcb:dd1c::/32ffcb:dd1c:ffff:ffff:ffff:ffff:ffff:ffff
30ffcb:dd1d::/32ffcb:dd1d:ffff:ffff:ffff:ffff:ffff:ffff
31ffcb:dd1e::/32ffcb:dd1e:ffff:ffff:ffff:ffff:ffff:ffff
32ffcb:dd1f::/32ffcb:dd1f:ffff:ffff:ffff:ffff:ffff:ffff
33ffcb:dd20::/32ffcb:dd20:ffff:ffff:ffff:ffff:ffff:ffff
34ffcb:dd21::/32ffcb:dd21:ffff:ffff:ffff:ffff:ffff:ffff
35ffcb:dd22::/32ffcb:dd22:ffff:ffff:ffff:ffff:ffff:ffff
36ffcb:dd23::/32ffcb:dd23:ffff:ffff:ffff:ffff:ffff:ffff
37ffcb:dd24::/32ffcb:dd24:ffff:ffff:ffff:ffff:ffff:ffff
38ffcb:dd25::/32ffcb:dd25:ffff:ffff:ffff:ffff:ffff:ffff
39ffcb:dd26::/32ffcb:dd26:ffff:ffff:ffff:ffff:ffff:ffff
40ffcb:dd27::/32ffcb:dd27:ffff:ffff:ffff:ffff:ffff:ffff
41ffcb:dd28::/32ffcb:dd28:ffff:ffff:ffff:ffff:ffff:ffff
42ffcb:dd29::/32ffcb:dd29:ffff:ffff:ffff:ffff:ffff:ffff
43ffcb:dd2a::/32ffcb:dd2a:ffff:ffff:ffff:ffff:ffff:ffff
44ffcb:dd2b::/32ffcb:dd2b:ffff:ffff:ffff:ffff:ffff:ffff
45ffcb:dd2c::/32ffcb:dd2c:ffff:ffff:ffff:ffff:ffff:ffff
46ffcb:dd2d::/32ffcb:dd2d:ffff:ffff:ffff:ffff:ffff:ffff
47ffcb:dd2e::/32ffcb:dd2e:ffff:ffff:ffff:ffff:ffff:ffff
48ffcb:dd2f::/32ffcb:dd2f:ffff:ffff:ffff:ffff:ffff:ffff
49ffcb:dd30::/32ffcb:dd30:ffff:ffff:ffff:ffff:ffff:ffff
50ffcb:dd31::/32ffcb:dd31:ffff:ffff:ffff:ffff:ffff:ffff
51ffcb:dd32::/32ffcb:dd32:ffff:ffff:ffff:ffff:ffff:ffff
52ffcb:dd33::/32ffcb:dd33:ffff:ffff:ffff:ffff:ffff:ffff
53ffcb:dd34::/32ffcb:dd34:ffff:ffff:ffff:ffff:ffff:ffff
54ffcb:dd35::/32ffcb:dd35:ffff:ffff:ffff:ffff:ffff:ffff
55ffcb:dd36::/32ffcb:dd36:ffff:ffff:ffff:ffff:ffff:ffff
56ffcb:dd37::/32ffcb:dd37:ffff:ffff:ffff:ffff:ffff:ffff
57ffcb:dd38::/32ffcb:dd38:ffff:ffff:ffff:ffff:ffff:ffff
58ffcb:dd39::/32ffcb:dd39:ffff:ffff:ffff:ffff:ffff:ffff
59ffcb:dd3a::/32ffcb:dd3a:ffff:ffff:ffff:ffff:ffff:ffff
60ffcb:dd3b::/32ffcb:dd3b:ffff:ffff:ffff:ffff:ffff:ffff
61ffcb:dd3c::/32ffcb:dd3c:ffff:ffff:ffff:ffff:ffff:ffff
62ffcb:dd3d::/32ffcb:dd3d:ffff:ffff:ffff:ffff:ffff:ffff
63ffcb:dd3e::/32ffcb:dd3e:ffff:ffff:ffff:ffff:ffff:ffff
64ffcb:dd3f::/32ffcb:dd3f:ffff:ffff:ffff:ffff:ffff:ffff
65ffcb:dd40::/32ffcb:dd40:ffff:ffff:ffff:ffff:ffff:ffff
66ffcb:dd41::/32ffcb:dd41:ffff:ffff:ffff:ffff:ffff:ffff
67ffcb:dd42::/32ffcb:dd42:ffff:ffff:ffff:ffff:ffff:ffff
68ffcb:dd43::/32ffcb:dd43:ffff:ffff:ffff:ffff:ffff:ffff
69ffcb:dd44::/32ffcb:dd44:ffff:ffff:ffff:ffff:ffff:ffff
70ffcb:dd45::/32ffcb:dd45:ffff:ffff:ffff:ffff:ffff:ffff
71ffcb:dd46::/32ffcb:dd46:ffff:ffff:ffff:ffff:ffff:ffff
72ffcb:dd47::/32ffcb:dd47:ffff:ffff:ffff:ffff:ffff:ffff
73ffcb:dd48::/32ffcb:dd48:ffff:ffff:ffff:ffff:ffff:ffff
74ffcb:dd49::/32ffcb:dd49:ffff:ffff:ffff:ffff:ffff:ffff
75ffcb:dd4a::/32ffcb:dd4a:ffff:ffff:ffff:ffff:ffff:ffff
76ffcb:dd4b::/32ffcb:dd4b:ffff:ffff:ffff:ffff:ffff:ffff
77ffcb:dd4c::/32ffcb:dd4c:ffff:ffff:ffff:ffff:ffff:ffff
78ffcb:dd4d::/32ffcb:dd4d:ffff:ffff:ffff:ffff:ffff:ffff
79ffcb:dd4e::/32ffcb:dd4e:ffff:ffff:ffff:ffff:ffff:ffff
80ffcb:dd4f::/32ffcb:dd4f:ffff:ffff:ffff:ffff:ffff:ffff
81ffcb:dd50::/32ffcb:dd50:ffff:ffff:ffff:ffff:ffff:ffff
82ffcb:dd51::/32ffcb:dd51:ffff:ffff:ffff:ffff:ffff:ffff
83ffcb:dd52::/32ffcb:dd52:ffff:ffff:ffff:ffff:ffff:ffff
84ffcb:dd53::/32ffcb:dd53:ffff:ffff:ffff:ffff:ffff:ffff
85ffcb:dd54::/32ffcb:dd54:ffff:ffff:ffff:ffff:ffff:ffff
86ffcb:dd55::/32ffcb:dd55:ffff:ffff:ffff:ffff:ffff:ffff
87ffcb:dd56::/32ffcb:dd56:ffff:ffff:ffff:ffff:ffff:ffff
88ffcb:dd57::/32ffcb:dd57:ffff:ffff:ffff:ffff:ffff:ffff
89ffcb:dd58::/32ffcb:dd58:ffff:ffff:ffff:ffff:ffff:ffff
90ffcb:dd59::/32ffcb:dd59:ffff:ffff:ffff:ffff:ffff:ffff
91ffcb:dd5a::/32ffcb:dd5a:ffff:ffff:ffff:ffff:ffff:ffff
92ffcb:dd5b::/32ffcb:dd5b:ffff:ffff:ffff:ffff:ffff:ffff
93ffcb:dd5c::/32ffcb:dd5c:ffff:ffff:ffff:ffff:ffff:ffff
94ffcb:dd5d::/32ffcb:dd5d:ffff:ffff:ffff:ffff:ffff:ffff
95ffcb:dd5e::/32ffcb:dd5e:ffff:ffff:ffff:ffff:ffff:ffff
96ffcb:dd5f::/32ffcb:dd5f:ffff:ffff:ffff:ffff:ffff:ffff
97ffcb:dd60::/32ffcb:dd60:ffff:ffff:ffff:ffff:ffff:ffff
98ffcb:dd61::/32ffcb:dd61:ffff:ffff:ffff:ffff:ffff:ffff
99ffcb:dd62::/32ffcb:dd62:ffff:ffff:ffff:ffff:ffff:ffff
100ffcb:dd63::/32ffcb:dd63:ffff:ffff:ffff:ffff:ffff:ffff
101ffcb:dd64::/32ffcb:dd64:ffff:ffff:ffff:ffff:ffff:ffff
102ffcb:dd65::/32ffcb:dd65:ffff:ffff:ffff:ffff:ffff:ffff
103ffcb:dd66::/32ffcb:dd66:ffff:ffff:ffff:ffff:ffff:ffff
104ffcb:dd67::/32ffcb:dd67:ffff:ffff:ffff:ffff:ffff:ffff
105ffcb:dd68::/32ffcb:dd68:ffff:ffff:ffff:ffff:ffff:ffff
106ffcb:dd69::/32ffcb:dd69:ffff:ffff:ffff:ffff:ffff:ffff
107ffcb:dd6a::/32ffcb:dd6a:ffff:ffff:ffff:ffff:ffff:ffff
108ffcb:dd6b::/32ffcb:dd6b:ffff:ffff:ffff:ffff:ffff:ffff
109ffcb:dd6c::/32ffcb:dd6c:ffff:ffff:ffff:ffff:ffff:ffff
110ffcb:dd6d::/32ffcb:dd6d:ffff:ffff:ffff:ffff:ffff:ffff
111ffcb:dd6e::/32ffcb:dd6e:ffff:ffff:ffff:ffff:ffff:ffff
112ffcb:dd6f::/32ffcb:dd6f:ffff:ffff:ffff:ffff:ffff:ffff
113ffcb:dd70::/32ffcb:dd70:ffff:ffff:ffff:ffff:ffff:ffff
114ffcb:dd71::/32ffcb:dd71:ffff:ffff:ffff:ffff:ffff:ffff
115ffcb:dd72::/32ffcb:dd72:ffff:ffff:ffff:ffff:ffff:ffff
116ffcb:dd73::/32ffcb:dd73:ffff:ffff:ffff:ffff:ffff:ffff
117ffcb:dd74::/32ffcb:dd74:ffff:ffff:ffff:ffff:ffff:ffff
118ffcb:dd75::/32ffcb:dd75:ffff:ffff:ffff:ffff:ffff:ffff
119ffcb:dd76::/32ffcb:dd76:ffff:ffff:ffff:ffff:ffff:ffff
120ffcb:dd77::/32ffcb:dd77:ffff:ffff:ffff:ffff:ffff:ffff
121ffcb:dd78::/32ffcb:dd78:ffff:ffff:ffff:ffff:ffff:ffff
122ffcb:dd79::/32ffcb:dd79:ffff:ffff:ffff:ffff:ffff:ffff
123ffcb:dd7a::/32ffcb:dd7a:ffff:ffff:ffff:ffff:ffff:ffff
124ffcb:dd7b::/32ffcb:dd7b:ffff:ffff:ffff:ffff:ffff:ffff
125ffcb:dd7c::/32ffcb:dd7c:ffff:ffff:ffff:ffff:ffff:ffff
126ffcb:dd7d::/32ffcb:dd7d:ffff:ffff:ffff:ffff:ffff:ffff
127ffcb:dd7e::/32ffcb:dd7e:ffff:ffff:ffff:ffff:ffff:ffff
128ffcb:dd7f::/32ffcb:dd7f:ffff:ffff:ffff:ffff:ffff:ffff
129ffcb:dd80::/32ffcb:dd80:ffff:ffff:ffff:ffff:ffff:ffff
130ffcb:dd81::/32ffcb:dd81:ffff:ffff:ffff:ffff:ffff:ffff
131ffcb:dd82::/32ffcb:dd82:ffff:ffff:ffff:ffff:ffff:ffff
132ffcb:dd83::/32ffcb:dd83:ffff:ffff:ffff:ffff:ffff:ffff
133ffcb:dd84::/32ffcb:dd84:ffff:ffff:ffff:ffff:ffff:ffff
134ffcb:dd85::/32ffcb:dd85:ffff:ffff:ffff:ffff:ffff:ffff
135ffcb:dd86::/32ffcb:dd86:ffff:ffff:ffff:ffff:ffff:ffff
136ffcb:dd87::/32ffcb:dd87:ffff:ffff:ffff:ffff:ffff:ffff
137ffcb:dd88::/32ffcb:dd88:ffff:ffff:ffff:ffff:ffff:ffff
138ffcb:dd89::/32ffcb:dd89:ffff:ffff:ffff:ffff:ffff:ffff
139ffcb:dd8a::/32ffcb:dd8a:ffff:ffff:ffff:ffff:ffff:ffff
140ffcb:dd8b::/32ffcb:dd8b:ffff:ffff:ffff:ffff:ffff:ffff
141ffcb:dd8c::/32ffcb:dd8c:ffff:ffff:ffff:ffff:ffff:ffff
142ffcb:dd8d::/32ffcb:dd8d:ffff:ffff:ffff:ffff:ffff:ffff
143ffcb:dd8e::/32ffcb:dd8e:ffff:ffff:ffff:ffff:ffff:ffff
144ffcb:dd8f::/32ffcb:dd8f:ffff:ffff:ffff:ffff:ffff:ffff
145ffcb:dd90::/32ffcb:dd90:ffff:ffff:ffff:ffff:ffff:ffff
146ffcb:dd91::/32ffcb:dd91:ffff:ffff:ffff:ffff:ffff:ffff
147ffcb:dd92::/32ffcb:dd92:ffff:ffff:ffff:ffff:ffff:ffff
148ffcb:dd93::/32ffcb:dd93:ffff:ffff:ffff:ffff:ffff:ffff
149ffcb:dd94::/32ffcb:dd94:ffff:ffff:ffff:ffff:ffff:ffff
150ffcb:dd95::/32ffcb:dd95:ffff:ffff:ffff:ffff:ffff:ffff
151ffcb:dd96::/32ffcb:dd96:ffff:ffff:ffff:ffff:ffff:ffff
152ffcb:dd97::/32ffcb:dd97:ffff:ffff:ffff:ffff:ffff:ffff
153ffcb:dd98::/32ffcb:dd98:ffff:ffff:ffff:ffff:ffff:ffff
154ffcb:dd99::/32ffcb:dd99:ffff:ffff:ffff:ffff:ffff:ffff
155ffcb:dd9a::/32ffcb:dd9a:ffff:ffff:ffff:ffff:ffff:ffff
156ffcb:dd9b::/32ffcb:dd9b:ffff:ffff:ffff:ffff:ffff:ffff
157ffcb:dd9c::/32ffcb:dd9c:ffff:ffff:ffff:ffff:ffff:ffff
158ffcb:dd9d::/32ffcb:dd9d:ffff:ffff:ffff:ffff:ffff:ffff
159ffcb:dd9e::/32ffcb:dd9e:ffff:ffff:ffff:ffff:ffff:ffff
160ffcb:dd9f::/32ffcb:dd9f:ffff:ffff:ffff:ffff:ffff:ffff
161ffcb:dda0::/32ffcb:dda0:ffff:ffff:ffff:ffff:ffff:ffff
162ffcb:dda1::/32ffcb:dda1:ffff:ffff:ffff:ffff:ffff:ffff
163ffcb:dda2::/32ffcb:dda2:ffff:ffff:ffff:ffff:ffff:ffff
164ffcb:dda3::/32ffcb:dda3:ffff:ffff:ffff:ffff:ffff:ffff
165ffcb:dda4::/32ffcb:dda4:ffff:ffff:ffff:ffff:ffff:ffff
166ffcb:dda5::/32ffcb:dda5:ffff:ffff:ffff:ffff:ffff:ffff
167ffcb:dda6::/32ffcb:dda6:ffff:ffff:ffff:ffff:ffff:ffff
168ffcb:dda7::/32ffcb:dda7:ffff:ffff:ffff:ffff:ffff:ffff
169ffcb:dda8::/32ffcb:dda8:ffff:ffff:ffff:ffff:ffff:ffff
170ffcb:dda9::/32ffcb:dda9:ffff:ffff:ffff:ffff:ffff:ffff
171ffcb:ddaa::/32ffcb:ddaa:ffff:ffff:ffff:ffff:ffff:ffff
172ffcb:ddab::/32ffcb:ddab:ffff:ffff:ffff:ffff:ffff:ffff
173ffcb:ddac::/32ffcb:ddac:ffff:ffff:ffff:ffff:ffff:ffff
174ffcb:ddad::/32ffcb:ddad:ffff:ffff:ffff:ffff:ffff:ffff
175ffcb:ddae::/32ffcb:ddae:ffff:ffff:ffff:ffff:ffff:ffff
176ffcb:ddaf::/32ffcb:ddaf:ffff:ffff:ffff:ffff:ffff:ffff
177ffcb:ddb0::/32ffcb:ddb0:ffff:ffff:ffff:ffff:ffff:ffff
178ffcb:ddb1::/32ffcb:ddb1:ffff:ffff:ffff:ffff:ffff:ffff
179ffcb:ddb2::/32ffcb:ddb2:ffff:ffff:ffff:ffff:ffff:ffff
180ffcb:ddb3::/32ffcb:ddb3:ffff:ffff:ffff:ffff:ffff:ffff
181ffcb:ddb4::/32ffcb:ddb4:ffff:ffff:ffff:ffff:ffff:ffff
182ffcb:ddb5::/32ffcb:ddb5:ffff:ffff:ffff:ffff:ffff:ffff
183ffcb:ddb6::/32ffcb:ddb6:ffff:ffff:ffff:ffff:ffff:ffff
184ffcb:ddb7::/32ffcb:ddb7:ffff:ffff:ffff:ffff:ffff:ffff
185ffcb:ddb8::/32ffcb:ddb8:ffff:ffff:ffff:ffff:ffff:ffff
186ffcb:ddb9::/32ffcb:ddb9:ffff:ffff:ffff:ffff:ffff:ffff
187ffcb:ddba::/32ffcb:ddba:ffff:ffff:ffff:ffff:ffff:ffff
188ffcb:ddbb::/32ffcb:ddbb:ffff:ffff:ffff:ffff:ffff:ffff
189ffcb:ddbc::/32ffcb:ddbc:ffff:ffff:ffff:ffff:ffff:ffff
190ffcb:ddbd::/32ffcb:ddbd:ffff:ffff:ffff:ffff:ffff:ffff
191ffcb:ddbe::/32ffcb:ddbe:ffff:ffff:ffff:ffff:ffff:ffff
192ffcb:ddbf::/32ffcb:ddbf:ffff:ffff:ffff:ffff:ffff:ffff
193ffcb:ddc0::/32ffcb:ddc0:ffff:ffff:ffff:ffff:ffff:ffff
194ffcb:ddc1::/32ffcb:ddc1:ffff:ffff:ffff:ffff:ffff:ffff
195ffcb:ddc2::/32ffcb:ddc2:ffff:ffff:ffff:ffff:ffff:ffff
196ffcb:ddc3::/32ffcb:ddc3:ffff:ffff:ffff:ffff:ffff:ffff
197ffcb:ddc4::/32ffcb:ddc4:ffff:ffff:ffff:ffff:ffff:ffff
198ffcb:ddc5::/32ffcb:ddc5:ffff:ffff:ffff:ffff:ffff:ffff
199ffcb:ddc6::/32ffcb:ddc6:ffff:ffff:ffff:ffff:ffff:ffff
200ffcb:ddc7::/32ffcb:ddc7:ffff:ffff:ffff:ffff:ffff:ffff
201ffcb:ddc8::/32ffcb:ddc8:ffff:ffff:ffff:ffff:ffff:ffff
202ffcb:ddc9::/32ffcb:ddc9:ffff:ffff:ffff:ffff:ffff:ffff
203ffcb:ddca::/32ffcb:ddca:ffff:ffff:ffff:ffff:ffff:ffff
204ffcb:ddcb::/32ffcb:ddcb:ffff:ffff:ffff:ffff:ffff:ffff
205ffcb:ddcc::/32ffcb:ddcc:ffff:ffff:ffff:ffff:ffff:ffff
206ffcb:ddcd::/32ffcb:ddcd:ffff:ffff:ffff:ffff:ffff:ffff
207ffcb:ddce::/32ffcb:ddce:ffff:ffff:ffff:ffff:ffff:ffff
208ffcb:ddcf::/32ffcb:ddcf:ffff:ffff:ffff:ffff:ffff:ffff
209ffcb:ddd0::/32ffcb:ddd0:ffff:ffff:ffff:ffff:ffff:ffff
210ffcb:ddd1::/32ffcb:ddd1:ffff:ffff:ffff:ffff:ffff:ffff
211ffcb:ddd2::/32ffcb:ddd2:ffff:ffff:ffff:ffff:ffff:ffff
212ffcb:ddd3::/32ffcb:ddd3:ffff:ffff:ffff:ffff:ffff:ffff
213ffcb:ddd4::/32ffcb:ddd4:ffff:ffff:ffff:ffff:ffff:ffff
214ffcb:ddd5::/32ffcb:ddd5:ffff:ffff:ffff:ffff:ffff:ffff
215ffcb:ddd6::/32ffcb:ddd6:ffff:ffff:ffff:ffff:ffff:ffff
216ffcb:ddd7::/32ffcb:ddd7:ffff:ffff:ffff:ffff:ffff:ffff
217ffcb:ddd8::/32ffcb:ddd8:ffff:ffff:ffff:ffff:ffff:ffff
218ffcb:ddd9::/32ffcb:ddd9:ffff:ffff:ffff:ffff:ffff:ffff
219ffcb:ddda::/32ffcb:ddda:ffff:ffff:ffff:ffff:ffff:ffff
220ffcb:dddb::/32ffcb:dddb:ffff:ffff:ffff:ffff:ffff:ffff
221ffcb:dddc::/32ffcb:dddc:ffff:ffff:ffff:ffff:ffff:ffff
222ffcb:dddd::/32ffcb:dddd:ffff:ffff:ffff:ffff:ffff:ffff
223ffcb:ddde::/32ffcb:ddde:ffff:ffff:ffff:ffff:ffff:ffff
224ffcb:dddf::/32ffcb:dddf:ffff:ffff:ffff:ffff:ffff:ffff
225ffcb:dde0::/32ffcb:dde0:ffff:ffff:ffff:ffff:ffff:ffff
226ffcb:dde1::/32ffcb:dde1:ffff:ffff:ffff:ffff:ffff:ffff
227ffcb:dde2::/32ffcb:dde2:ffff:ffff:ffff:ffff:ffff:ffff
228ffcb:dde3::/32ffcb:dde3:ffff:ffff:ffff:ffff:ffff:ffff
229ffcb:dde4::/32ffcb:dde4:ffff:ffff:ffff:ffff:ffff:ffff
230ffcb:dde5::/32ffcb:dde5:ffff:ffff:ffff:ffff:ffff:ffff
231ffcb:dde6::/32ffcb:dde6:ffff:ffff:ffff:ffff:ffff:ffff
232ffcb:dde7::/32ffcb:dde7:ffff:ffff:ffff:ffff:ffff:ffff
233ffcb:dde8::/32ffcb:dde8:ffff:ffff:ffff:ffff:ffff:ffff
234ffcb:dde9::/32ffcb:dde9:ffff:ffff:ffff:ffff:ffff:ffff
235ffcb:ddea::/32ffcb:ddea:ffff:ffff:ffff:ffff:ffff:ffff
236ffcb:ddeb::/32ffcb:ddeb:ffff:ffff:ffff:ffff:ffff:ffff
237ffcb:ddec::/32ffcb:ddec:ffff:ffff:ffff:ffff:ffff:ffff
238ffcb:dded::/32ffcb:dded:ffff:ffff:ffff:ffff:ffff:ffff
239ffcb:ddee::/32ffcb:ddee:ffff:ffff:ffff:ffff:ffff:ffff
240ffcb:ddef::/32ffcb:ddef:ffff:ffff:ffff:ffff:ffff:ffff
241ffcb:ddf0::/32ffcb:ddf0:ffff:ffff:ffff:ffff:ffff:ffff
242ffcb:ddf1::/32ffcb:ddf1:ffff:ffff:ffff:ffff:ffff:ffff
243ffcb:ddf2::/32ffcb:ddf2:ffff:ffff:ffff:ffff:ffff:ffff
244ffcb:ddf3::/32ffcb:ddf3:ffff:ffff:ffff:ffff:ffff:ffff
245ffcb:ddf4::/32ffcb:ddf4:ffff:ffff:ffff:ffff:ffff:ffff
246ffcb:ddf5::/32ffcb:ddf5:ffff:ffff:ffff:ffff:ffff:ffff
247ffcb:ddf6::/32ffcb:ddf6:ffff:ffff:ffff:ffff:ffff:ffff
248ffcb:ddf7::/32ffcb:ddf7:ffff:ffff:ffff:ffff:ffff:ffff
249ffcb:ddf8::/32ffcb:ddf8:ffff:ffff:ffff:ffff:ffff:ffff
250ffcb:ddf9::/32ffcb:ddf9:ffff:ffff:ffff:ffff:ffff:ffff
251ffcb:ddfa::/32ffcb:ddfa:ffff:ffff:ffff:ffff:ffff:ffff
252ffcb:ddfb::/32ffcb:ddfb:ffff:ffff:ffff:ffff:ffff:ffff
253ffcb:ddfc::/32ffcb:ddfc:ffff:ffff:ffff:ffff:ffff:ffff
254ffcb:ddfd::/32ffcb:ddfd:ffff:ffff:ffff:ffff:ffff:ffff
255ffcb:ddfe::/32ffcb:ddfe:ffff:ffff:ffff:ffff:ffff:ffff
256ffcb:ddff::/32ffcb:ddff: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.