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IP address


The primary function of the Internet is the exchange of data between computers; to accomplish this, every computer of the Internet network has an IP address.

The most common IP nowadays is the Ipv4. In the Ipv4 the address of the computer is in a row of 32 bits (2 to the power of 4-bits); this is represented by 4 octets, for example: 151.23.40.3. There is also a version that uses 128 bits (2 to the power of 6 bits).

Most IP addresses of the Internet can go into 4 classifications:
1) The first bit in the 32 is, "0" and represents the class A; the next 7 bits show the network's address, while the last 24 bits indicate the computer's address in the network.

2) The first 2 bits out of the 32 are "1 0" and they represent class B, the next 14 bits show the network's address, while the last 16 indicate the computer that is on the network.

3) The first 3 bits out of the 32 are "1 1 0" and they represent class C, the next 21 bits show the network's address, while the last 8 bits indicate the computer's address that is on the network.

4) The first 4 bits out of the 32 are "1 1 1 0" they represent class D, the next 28 bits are used to show a single address which, in this case, is called a multicast address.

IP addresses are difficult to memorize in numeric format, that's why a method of attaching the name through a domain system (the DNS-Domain Name System) was introduced. In essence, the DNS represents a method of naming the computer (real or virtual) through a network based on TCP/IP (on a type of Internet) using a hierarchy scheme.

Example: imap.des.kel.ac.uk is the name of the computer that is responsible for managing the electronic mail (IMAP) from a certain department (des.kel) belonging to a sub network Internet (ac) in Great Britain (uk). Every suffix from a name is called a domain. The relationship "des.kel.ac.uk < kel.ac.uk < ac.uk < uk" where "<" means, "included in", and shows the hierarchical nature of the notation.

The determination of the IP address, coming from the name, is done by interrogating a server for the Domain name. DNS =the multitude of all this name-servers.


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