|Internet Protocol Version 4 / IPv4|
Components of an Internet Protocol version 4/IPv4 address
IPv4 uses 32-bit addresses, so if you view the address in its binary format, it has 32 characters, as the following example shows:
1. The unique identity of the computer, which is the host ID.
2. The subnet on which the computer resides, which is the network ID.
3. This enables a networked computer to communicate with other networked computers in a routed environment.
Internet Protocol address version 4 /IPv4 classes
The Internet Assigned Numbers Authority (IANA) organizes IPv4 addresses into classes. The number of hosts that a network has determines the class of addresses that is required. IANA has named the IPv4 address classes from Class A through Class E.
Class A = Any IP address in which the first octet has a value between 1 and 127 is a part of a Class A network. there are only 126 available Class A network, each with up to 16,777,214 hosts.
Because Class A networks are very large, they are allocated to very large organizations. It is no longer possible for individual companies to obtains Class A Networks.
Class A subnet Mask is 255.0.0.0
Note : All IP address on the network 127.0.0.0 refer to the local host. The Internet Protocol / IP addre4ss on this network are used for diagnostics only.
Class B = An Internet Protocol / IP address in which the first octet has value between 128 and 191 is part of a Class B Network. There are 16,384 Class B Network, each with up to 65,534 hosts .Class B Networks are assigned to a variety of large companies and universities. For example, the 126.96.36.199 network is allocated to Microsoft Corporation.
Class B subnet Mask is 255.255.0.0
Class C = An Internet protocol / IP address in which the first octet has value between 192 to 223 is part of a Class C Network. There are 2,097,152 Class C Networks, each with up to 254 hosts.Class C address are assigned to many small and medium-size organization. In some cases, companies are assigned a Class C Network for each of their locations.
Class C subnet Mask is 255.255.255.0
Class D = An Internet protocol / IP address in which the first octet has value between 224 to 239 is part of a Class D Network. Class D address are not assigned to a individual hosts. Class D addresses are assigned to groups of computers called multicast groups. Using multicast groups is an efficient way to deliver information on a network when multiple hosts need the same information at the same time.
Class E = An Internet protocol / IP address in which the first octet has value 240 is part of a Class E Network. This Class E network are reserved for experimental use and are never used on TCP/IP networks except for the broadcast address. The address 255.255.255.255 is a broadcast. Packets addressed to this Internet Protocol Address are delivered to all host on the local network.
Broadcasts are used when applications are not configured with the Internet Protocol address of the host that they should be contacting. For example, Dynamic Host Control Protocol / DHCP clients use broadcasts to communicative with a DHCP server and obtain an Internet Protocol / IP address.