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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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