Specifications
1 - 3
1.2.2 IP address
The IP address (Internet Protocol Address) is an identification number assigned to
identify each device or computer connected to the IP network such as the Internet or
intranet. (It corresponds to a mail address or a telephone number)
Unique addresses managed by each country are used on the internet where the
network is connected on a global scale.
An IP address is expressed by a 32-bit number for IP
V4, which is now used commonly.
It is generally divided into 4 parts of 8 bits like "192.168.1.1" and represented as
decimal notation.
The 32-bit value consists of the network part which identifies each network and the
host part which identifies the connected device in the network (PC, etc.)
(IP address) = ((Class) + network part address) + (host part address)
Representations of IP address
An IP address (IPv4) is described by a 32-bit number.
Binary number 00000000000000000000000000000000 to 11111111111111111111111111111111
Decimal number 0 to 4294967295
Hexadecimal number 0 to FFFFFFFF
They are divided by 8 bits for easier comprehension.
Binary number 00000000.00000000.00000000.00000000 to 11111111.11111111.11111111.11111111
Decimal number 0. 0. 0. 0 to 255. 255. 255. 255
Hexadecimal number 0. 0. 0. 0 to FF. FF. FF. FF
(1) Classification by class
The classification system called "class" has been traditionally used to fixedly
handle the boundary between the IP address network part and the host part .
Class Bit assignment (*1)
Higher bits -----------------------Lower bits
Higher 8 bits Boundary of
network address
Private IP address range
Class A
0
1
7
24
Network
part (8)
Host part (24)
Net ID
Host ID
0*******
(0 to 127)
8 bits from the
highest
10.0.0.0 to 10.255.255.255
Class B
2 14
16
01
Network part(16)
Host part(16)
Net ID
Host ID
10******
(128 to 191)
16 bits from the
highest
172.16.0.0 to 172.31.255.255
Class C
3 21 8
110
Network part(24)
Host part(8)
Net ID
Host ID
110*****
(192 to 223)
24 bits from the
highest
192.168.0.0 to 192.168.255.255
*1 The
part at the higher of the IP addresses indicates classes.
The classes A to C are the addresses for public use.
The address usable for the devices that are not directly connected to the Internet
is called "private IP address".