Classes of IP Address | Learn how to Hack
The octets serve
a purpose other than simply separating the numbers. They are used to create classes of IP
addresses that
can be assigned to a particular business, government or other entity based on
size and need. The octets are split into two sections: Net and Host. The Net section
always contains the first octet. It
is used to identify the network that
a computer belongs
to. Host (sometimes referred to as Node) identifies the actual
computer on the network. The Host section
always contains the last octet.
There are five IP classes plus certain special addresses
Class
A – This class is for very large networks, such as a major
international company might have. IP addresses with a
first octet from 1 to 126 are part of this class. The other three octets are
used to identify each host. This means that there are 126 Class A networks
each with 16,777,214 (224 -2) possible hosts for a total of 2,147,483,648
(231) unique IP addresses. Class A networks account for half of the total
available IP addresses. In Class A networks, the high order bit value (the very
first binary number) in the first octet is always 0.
|
Net
|
Host or Node
|
|
115.
|
24.53.107
|
Loopback – The IP address 127.0.0.1 is used as the loopback address. This
means that it is used by the host computer to send a message back to itself. It
is commonly used for troubleshooting and network testing.
·
Class B – Class B is used for
medium-sized networks. A good example is a large college campus. IP
addresses with a first octet from 128 to 191 are part of this class. Class B
addresses also include the second octet as part of the Net identifier. The
other two octets are used to identify each host. This means that there are
16,384 (214) Class B networks each with 65,534 (216 -2) possible hosts for a total of
1,073,741,824 (230) unique IP addresses. Class B networks make up a
quarter of the total available IP addresses. Class B networks have a first bit
value of 1 and a second bit value of 0 in the first octet.
|
Net
|
Host or Node
|
|
145.24.
|
53.107
|
·
Class C – Class C addresses are commonly used for small
to mid-size businesses. IP addresses with a first octet from 192 to 223 are
part of this class. Class C addresses also include the second and third octets
as part of the Net identifier. The last octet is used to identify each host.
This means that there are 2,097,152 (221) Class C networks each with
254 (28 -2) possible
hosts for a total of 536,870,912 (229) unique IP addresses. Class C
networks make up an eighth of the total available IP addresses. Class C
networks have a first bit value of 1, second bit value of 1 and a third bit
value of 0 in the first octet.
|
Net
|
Host or Node
|
|
195.24.53.
|
107
|
·
Class D – Used for multicasts, Class D is slightly different from the first
three classes. It has a first bit value of 1, second bit value of 1, third bit
value of 1 and fourth bit value of 0. The other 28 bits are used to identify
the group of computers the multicast message is intended for. Class D accounts
for 1/16th (268,435,456
or 228) of the available IP addresses.
|
Net
|
Host or Node
|
|
224.
|
24.53.107
|
·
Class E - Class E is used for experimental purposes only.
Like Class D, it is different from the first three classes. It has a first bit
value of 1, second bit value of 1, third bit value of 1 and fourth bit value of
1. The other 28 bits are used to identify the group of computers the multicast
message is intended for. Class E accounts for 1/16th(268,435,456 or
228) of the available IP
addresses.
|
Net
|
Host or Node
|
|
240.
|
24.53.107
|
·
Broadcast – Messages that are intended for all
computers on a network are sent asbroadcasts. These messages always use the IP address 255.255.255.255
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