IP Address

IP Addressing

Internet Protocol Address (IP Address) is a unique address for computing devices which use to specify itself and communicate with other devices such as,

- Personal computers

- Tablets

- Smartphones

Any device connected to IP network must have an unique IP address within a network.IP address features can be charecterized as,

- IP address is made up of 32 binary bits, which can be broken down into 4 octets(1 octet= 8 bits) each seperated by dot(.).Here is how each octet convert to decimal.

1 1 1 1 1 1 1 1

128 64 32 16 8 4 2 1 (128+64+32+16+8+4+2+1=255)

- A simple IP address can be represented in both binary and decimal format.

10. 1. 23. 19 (decimal)

00001010. 00000001. 00010111. 00010011 (binary)

--octet-- --octet-- --octet-- --octet--

- These octets are broken down to provide an addressing scheme that can accomodate large and small networks portion.

- 32 bit IP address is divided into net id and host id based on classes.

- Network portion is assigned to specific entity,such as company.The company is free to allocate host addresses any what it wants.

	Class A	Class B	Class C
No. of octets for net and host id's	Net id-1 Octet Hosts- 3 octets	Net id-2 Octets Hosts- 2 octets	Net id-3 Octets Hosts- 1 octet
First Octet of IP Address	[0]000 0000	[10]00 0000	[110]0 0000
NetID bits used to identify the Class	1[0]	2[10]	3[110]
Usable number of bits of NetID	8-1=7	16-2=14	24-3=21
Range of first Octet	0-127	128-191	192-223
Possible NetID's	27 - 2= 126	214 = 16,384	221 = 2,097,152
Possible HostID's	224 - 2= 16,277,214	216 -2= 65,534	28 -2= 254
Example with Masking	0.0.0.0 to 127.255.255.255	128.0.0.0 to 191.255.255.255	192.0.0.0 to 223.255.255.255

Note: Class D and Class E are used for multicasting and Experintal purposes respectively.

Subnet Mask

Subnet Mask seperates the IP address into

- Network address

- Host address

Subnet mask is made by setting network bits to all '1's and setting host bits to all '0's.

With in a given network two host addresses are reserved for special purpose, and cannot be assigned to hosts.

The '0' address is assigned to a network address and '255' is assigned to a broadcast address, and they cannot be assigned to hosts.