Address Format |
Difference to last address |
Mask |
Addresses |
Relative to class |
Typical use |
Decimal |
2n |
A, B, C |
a.b.c.d / 32 |
+0.0.0.0 |
255.255.255.255 |
1 |
20 |
1⁄256 C |
Host route |
a.b.c.d / 31 |
+0.0.0.1 |
255.255.255.254 |
2 |
21 |
1⁄128 C |
Point to point links (RFC 3021) |
a.b.c.d / 30 |
+0.0.0.3 |
255.255.255.252 |
4 |
22 |
1⁄64 C |
Point to point links (glue network) |
a.b.c.d / 29 |
+0.0.0.7 |
255.255.255.248 |
8 |
23 |
1⁄32 C |
Smallest multi-host network |
a.b.c.d / 28 |
+0.0.0.15 |
255.255.255.240 |
16 |
24 |
1⁄16 C |
Small LAN |
a.b.c.d / 27 |
+0.0.0.31 |
255.255.255.224 |
32 |
25 |
⅛ C |
|
a.b.c.d / 26 |
+0.0.0.63 |
255.255.255.192 |
64 |
26 |
¼ C |
|
a.b.c.d / 25 |
+0.0.0.127 |
255.255.255.128 |
128 |
27 |
½ C |
Large LAN |
a.b.c.0 / 24 |
+0.0.0.255 |
255.255.255.0 |
256 |
28 |
1 C |
|
a.b.c.0 / 23 |
+0.0.1.255 |
255.255.254.0 |
512 |
29 |
2 C |
|
a.b.c.0 / 22 |
+0.0.3.255 |
255.255.252.0 |
1,024 |
210 |
4 C |
|
a.b.c.0 / 21 |
+0.0.7.255 |
255.255.248.0 |
2,048 |
211 |
8 C |
Small ISP / large business |
a.b.c.0 / 20 |
+0.0.15.255 |
255.255.240.0 |
4,096 |
212 |
16 C |
|
a.b.c.0 / 19 |
+0.0.31.255 |
255.255.224.0 |
8,192 |
213 |
32 C |
ISP / large business |
a.b.c.0 / 18 |
+0.0.63.255 |
255.255.192.0 |
16,384 |
214 |
64 C |
|
a.b.c.0 / 17 |
+0.0.127.255 |
255.255.128.0 |
32,768 |
215 |
128 C |
|
a.b.0.0 / 16 |
+0.0.255.255 |
255.255.0.0 |
65,536 |
216 |
256 C = B |
|
a.b.0.0 / 15 |
+0.1.255.255 |
255.254.0.0 |
1,31,072 |
217 |
2 B |
|
a.b.0.0 / 14 |
+0.3.255.255 |
255.252.0.0 |
2,62,144 |
218 |
4 B |
|
a.b.0.0 / 13 |
+0.7.255.255 |
255.248.0.0 |
5,24,288 |
219 |
8 B |
|
a.b.0.0 / 12 |
+0.15.255.255 |
255.240.0.0 |
10,48,576 |
220 |
16 B |
|
a.b.0.0 / 11 |
+0.31.255.255 |
255.224.0.0 |
20,97,152 |
221 |
32 B |
|
a.b.0.0 / 10 |
+0.63.255.255 |
255.192.0.0 |
41,94,304 |
222 |
64 B |
|
a.b.0.0 / 9 |
+0.127.255.255 |
255.128.0.0 |
83,88,608 |
223 |
128 B |
|
a.0.0.0 / 8 |
+0.255.255.255 |
255.0.0.0 |
1,67,77,216 |
224 |
256 B = A |
Largest IANA block allocation |
a.0.0.0 / 7 |
+1.255.255.255 |
254.0.0.0 |
3,35,54,432 |
225 |
2:00 AM |
|
a.0.0.0 / 6 |
+3.255.255.255 |
252.0.0.0 |
6,71,08,864 |
226 |
4:00 AM |
|
a.0.0.0 / 5 |
+7.255.255.255 |
248.0.0.0 |
13,42,17,728 |
227 |
8:00 AM |
|
a.0.0.0 / 4 |
+15.255.255.255 |
240.0.0.0 |
26,84,35,456 |
228 |
16 A |
|
a.0.0.0 / 3 |
+31.255.255.255 |
224.0.0.0 |
53,68,70,912 |
229 |
32 A |
|
a.0.0.0 / 2 |
+63.255.255.255 |
192.0.0.0 |
1,07,37,41,824 |
230 |
64 A |
|
a.0.0.0 / 1 |
+127.255.255.255 |
128.0.0.0 |
2,14,74,83,648 |
231 |
128 A |
|
0.0.0.0 / 0 |
+255.255.255.255 |
0.0.0.0 |
4,29,49,67,296 |
232 |
256 A |
|