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=== Original ClassfulAddressing ===

|| Class || Starts With Bits || Network Bit Length || Host Bit Length || Range of Host Addresses ||
|| Class A || 0 || 8 || 24 || 1.0.0.0 to 127.255.255.255 ||
|| Class B || 10 || 16 || 16 || 128.0.0.0 to 191.255.255.255 ||
|| Class C || 110 || 24 || 8 || 192.0.0.0 to 223.255.255.255 ||
|| Class D || 1110 |||| Multicast Address |||| 224.0.0.0 to 239.255.255.255 ||
|| Class E || 1111 |||| Reserved for future use |||| 240.0.0.0 to 255.255.255.255 ||

=== Subnetting ===

The bit pattern at the beginning of an address gave the type. But this is a very inefficient classification because what if someone needs only 256 addresses? Then you have to give them a class B.

So subnetting allows us to use a subnet mask to hand out smaller address ranges:

   124.0.0.0/255.255.255.240 or 124.0.0.0/28 is a classless '''subnet''' that has 16 IP addresses in it.

If you get confused, you can always translate the address and the subnet mast to binary and examine them there.

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