The Classes of IP addresses reference article from the English Wikipedia on 24-Apr-2004
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Classes of IP addresses

Sponsorship the way you would do it
< Internet Protocol

Table of contents
1 Class A
2 Class B
3 Class C
4 Class D
5 Class E
6 Special Addresses

Class A

First Octet Range: 0-127

0nnnnnnn.hhhhhhhh.hhhhhhhh.hhhhhhhh

Network Mask:

Class B

First Octet Range: 128-191

10nnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh

Class C

First Octet Range: 192-223

110nnnnn.nnnnnnnn.nnnnnnnn.hhhhhhhh

Class D

Class D addresses are multicast addresses.


First Octet Range: 224-239

1110mmmm.mmmmmmmm.mmmmmmmm.mmmmmmmm

Class E

Class E addresses are reserved for experimental use.


First Octet Range: 240-247

1111rrrr.rrrrrrrr.rrrrrrrr.rrrrrrrr

Special Addresses

Some addresses are reserved for special uses.

address purpose class # of addresses
  127.0.0.0 - 127.255.255.255 localhost A 16,777,216
   10.0.0.0 -  10.255.255.255 intranet A 16,777,216
 172.16.0.0 -  172.31.255.255 intranet B 1,048,576
192.168.0.0 - 192.168.255.255 intranet C 65,536


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