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Every computer
that communicates over the Internet
is assigned an IP
address that uniquely identifies the device
and distinguishes it from other computers
on the Internet.
An IP
address consists of 32 bits,
often shown as 4 octets
of numbers from 0-255 represented in decimal
form instead of binary
form. For example, the IP
address 168.212.226.204 in binary
form is 10101000.11010100.11100010.11001100.
But it is easier for us to remember decimals
than it is to remember binary
numbers, so we use decimals
to represent the IP
addresses when describing them. However,
the binary
number is important because that will determine
which class
of network
the IP
address belongs to. An IP
address consists of two parts, one
identifying the network
and one identifying the node,
or host.
The class
of the address determines which part belongs to the network
address and which part belongs to the node
address. All nodes
on a given network
share the same network
prefix but must have a unique host
number.
Class
A Network
- binary
address start with 0, therefore the decimal
number can be anywhere from 1 to 126. The first 8 bits
(the first octet)
identify the network
and the remaining 24 bits
indicate the host
within the network.
An example of a Class
A IP
address is 102.168.212.226, where
"102" identifies the network
and "168.212.226" identifies the host
on that network.
Class
B Network
- binary
addresses start with 10, therefore the decimal
number can be anywhere from 128 to 191. (The number
127 is reserved for loop-back
and is used for internal testing on the local
machine.) The first 16 bits
(the first two octets)
identify the network
and the remaining 16 bits
indicate the host
within the network.
An example of a Class
B IP
address is 168.212.226.204 where
"168.212" identifies the network
and "226.204" identifies the host
on that network.
Class
C Network
- binary
addresses start with 110, therefore the decimal
number can be anywhere from 192 to 223. The first 24
bits
(the first three octets)
identify the network
and the remaining 8 bits
indicate the host
within the network.
An example of a Class
C IP
address is 200.168.212.226 where
"200.168.212" identifies the network
and "226" identifies the host
on that network.
Class
D Network
- binary
addresses start with 1110, therefore the decimal
number can be anywhere from 224 to 239. Class
D networks
are used to support multicasting.
Class
E Network
- binary
addresses start with 1111, therefore the decimal
number can be anywhere from 240 to 255. Class
E networks are used for experimentation. They have
never been documented or utilized in a standard way.
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