➢ A defining feature of IPv4 is its 32-bit addresses. Every host and router on the Internet has an IP address that can be used in the Source address and Destination address fields of IP packets.
➢ Each host in the network must have a unique IP address because duplicate addresses would make routing impossible.
➢ IP Addressing is a hierarchical structure as the IP address combines two identifiers into one number.
➢ The first part identifies the network address, the second part, called the host part, identifies which particular machine it is on the network.
➢ IP address is a 32 bit (4 bytes= 4 octets) address that is mainly divided to network part (representing the network ID where the device is located in) & Host part (representing the ID of the host).
➢ An IP address is a 32 bit number like 11000000101010000000000100000001 in binary or 3232235777 in decimal.
➢ So it is written in 4 parts like 11000000.10101000.00000001.00000001 in binary form and 192.168.1.1 in decimal form. This way it is easier to understand
❑ IP addresses are divided into classes to define the large, medium, and small networks. .
❑ Class A addresses are assigned to larger networks (few networks, each with many hosts).
❑ Class B addresses are used for medium-sized networks (medium number of networks, each with a medium number of hosts).
❑ Class C for small networks (many networks, each with a few hosts).
❑ Class D for Multicasting
❑ Class E for Experimental purposes.
classes ❑ Note that all Class A network addresses begin with a binary 0. Network addresses with a first octet of 0 (binary 00000000) and 127 (binary 01111111) are reserved, so there are 126 potential Class A network numbers, which have a first dotted decimal number in the range 1 to 126.
❑ Class B network addresses begin with a binary 10, so that the range of the first decimal number in a Class B address is 128 to 191(binary 10000000 to 10111111). The second octet is also part of the Class B address, so that there are 2 14 = 16,384 Class B addresses.
❑ For Class C addresses, the first decimal number ranges from 192 to 223 (11000000 to 11011111). ❑ The total number of Class C addresses is 2 21 = 2,097,152.
IP address types
IP address could be one of three categories:
✓ Network address
✓ Host address
✓ Broadcast address
Public IP Addresses
o Unique addresses are required for each device on a network.
o Originally, an organization known as the Internet Assigned Numbers Authority (IANA) handled this procedure.
o No two machines that connect to a public network can have the same IP address because public IP addresses are global and standardized.
o Public IP address is used outside the network.
Private IP Addresses
➢ Private IP addresses are another solution to the problem of the impending exhaustion of public IP addresses.
➢ Private networks that are not connected to the Internet may use any host addresses, as long as each host within the private network is unique .