2. classes
For administrative reasons some time early in the development of the IP
protocol some arbitrary groups of addresses were formed into networks and
these networks were grouped into what are called classes. These classes
provide a number of standard size networks that could be allocated. The
ranges allocated are:
+--------------------------------------------------------+
| Network | Netmask | Network Addresses |
| Class | | |
+--------------------------------------------------------+
| A | 255.0.0.0 | 0.0.0.0 - 127.255.255.255 |
| B | 255.255.0.0 | 128.0.0.0 - 191.255.255.255 |
| C | 255.255.255.0 | 192.0.0.0 - 223.255.255.255 |
|Multicast| 240.0.0.0 | 224.0.0.0 - 239.255.255.255 |
+--------------------------------------------------------+
What addresses you should use depends on exactly what it is
that you are doing.
3. a private network
If you are building a private network and you never intend that network to be connected
to the Internet then you can choose whatever addresses you like. However, for safety
and consistency reasons there have been some IP network addresses that have been
reserved specifically for this purpose. These are specified in RFC1597 and are as
follows:
+---------------------------------------------------------+
| RESERVED PRIVATE NETWORK ALLOCATIONS |
+---------------------------------------------------------+
| Network | Netmask | Network Addresses |
| Class | | |
+---------------------------------------------------------+
| A | 255.0.0.0 | 10.0.0.0 - 10.255.255.255 |
| B | 255.255.0.0 | 172.16.0.0 - 172.31.255.255 |
| C | 255.255.255.0 | 192.168.0.0 - 192.168.255.255 |
+---------------------------------------------------------+
You should first decide how large you want your network to be and
then choose as many of the addresses as you require.
