A Class A address uses only the ?¬?rst octet to indicate the network address.
The remaining three octets are used for host addresses.
The ?¬?rst bit of a Class A address is always 0; therefore, the lowest number that can be
represented is 00000000 (decimal 0), and the highest number that can be represented
is 01111111 (decimal 127). However, these two network numbers, 0 and 127, are
reserved and cannot be used as a network address. Any address that starts with a value
between 1 and 126 in the ?¬?rst octet, then, is a Class A address.
?– Class B: The Class B address category was designed to support the needs of moderate-
to large-sized networks. A Class B address uses two of the four octets to indicate the
network address. The other two octets specify host addresses.
The ?¬?rst 2 bits of the ?¬?rst octet of a Class B address are always binary 10. The
remaining 6 bits might be populated with either 1s or 0s. Therefore, the lowest number
that can be represented with a Class B address is 10000000 (decimal 128), and the
highest number that can be represented is 10111111 (decimal 191). Any address that
starts with a value in the range of 128 to 191 in the ?¬?rst octet is a Class B address.
?– Class C: The Class C address category is the most commonly used of the original
address classes.
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