Computer networks

 IP address:-

Every machine in a network has another unique identifying number,called it's IP Address.An IP address is a group of four bytes(or 32 bits) each of which can be a number from 0 to 255. A typical IP address looks like this: 59.171.132.72

An internet protocol address (IP Address) is a logical numeric address that is assigned,to every single computer,printer, switch,router or any other device that is part of a TCP/IP based network because IP address that are logical , they can change.

Address is IPV4 are 32 bits long.this allows for a maximum of 4,294,967,296.

The IP address is the core component on which the networking architecture is built; no network exists without it. An IP address is a logical address that is used to uniquely identify every node in the network.

MAC Address:-

MAC addresses are unique 48-bits hardware number of a computer,which is embedded into network card (known as network interface card) during the time of manufacturing .MAC address is also known as physical address of a computer device.

Once a network has been set up,the nodes can communicate among themselves.But for proper communication,the nodes should be uniquely identifiable.If a node X sends some information for node Y on a network,then it is mandatory that nodes X and Y are uniquely identifiable on the network.let us see how this is achieved.

Each NIC has a universally unique address assigned to it by its manufacturer.This address is known as the MAC(Media Access Control) address of the card.It means that a machine with an NIC can be identified uniquely through its NIC's MAC address.The MAC address of an NIC is permanent and does not change.

MAC addresses are 12 -digit hexadecimal (or 48 bit) numbers.By convention,MAC addresses are usually written in one of the following two formats:
MM:MM:MM:SS:SS:SS
MM-MM-MM-SS-SS-SS

The first half (MM:MM:MM) of a MAC address contains the ID number of the adapter manufacturer.The second half (SS:SS:SS) of a MAC address represents the serial number assigned to the adapter (NIC) by its manufacturer.
For example,in the following MAC address.
00:A0:C9 : 14:C8:35

The prefix 00:A0:C9 indicates that the manufacturer is intel corporation,and the last tree numbers 14:C8:35 are given by the manufacturer (inter in this example) to this NIC.


A cookie is a small amount of data, generated by a website, and saved by your web browser.Its purpose is to remember information about you, similar to a preference life created by a software application.
While cookie serve many functions ,there most common purpose is to store login information for a specific site.some sites will save both your username and password in a cookie,while others will only  save your  username.When ever you check a box,that says remember me on this computer ,the website will generate a login cookie. Once you successfully login.eacb time you visite the website ,you may only need to enter your password or you might not need to log in at all.


In the computing words ,a session refers to a limited time of communication between two systems.some session involve a clients and a servers, while other sessions involve two Personal computers.
A common type of client/server session is a web or  HTTP session. An HTTP session is initiated  by a web browser each time you visit a website.while each page visit constitutes  an individual session,the term is often used to describe the entire time you spend on the website.

  • Represent some else.
  • Authorized to act on behalf of another.
  • A proxy server verifies and forwards incoming client requests to other servers for further communication. A proxy server is located between a client and a server where it acts as an intermediary between the two,such as a web browser and web server.
  • The proxy servers most important role is providing security.

HTTP :-
  • HTTP stand for Hyper text transfer protocol.
  • It is a protocol used to access the data on the world wide web (WWW).
  • The HTTP protocol can be used to transfer the data in the form of plain text, Hypertext ,audio,video, and so on.
  • This protocol is known as hyper text transfer protocol because of its efficiency that allow us to use in a hypertext environment where there are ocupied jumps from one document to another document.
  • HTTP is a similar to FTP as it also transfer the files from one host to another host.but,HTTP is similar than FTP as HTTP uses only one connection,i.e., no control connection to transfer the files.

What is a Blockchain?

A Blockchain is a distributed database or ledger than is shared among the nodes of a computer network. As a database,a blockchain stores information electronically in digital format. Blockchain are best known for their crucial role in Cryptocurrency systems,such as Bitcoin,for maintaining a secure and decentralized record of transaction.The innovation with a blockchain is that it guarantees the fidelity and security of a record of data and generates trust without the need for a trusted third party.

In data communication terminology ,a transmission media is a physical path between the transmitter and the receiver.i.e.,it is the panel through which data is sent from one place to another.

Types of transmission media:-


1) Guided Media :- The term refers to physical conductors such as twisted pairs, coaxial cable,and fiber optics.In twisted pair and coaxial cable,the signal travels as voltage and current signal whereas in optical fibre, the signal is in the form of light.

There are three types of guided media:-

1.Twisted pair cable
2.coaxial cable 
3.optical fiber cable

2) Unguided Media :- The Unguided medium 
Uses electro-magnetic waves that do not require a physical conductor.Example of Unguided medium include microwave, radiowaves ,infrared.
It is also referred to as wireless or unbounded transmission media. No physical medium is required for the transmission of electromagnetic signals.

Features:-
  • Signal is broadcasted through air.
  • Less secure
  • Used for larger distance 
There are three types of Unguided Media:
  1. Radiowaves :- there are easy to generate and can penetrate through buildings.the sending and receiving antennas need not be aligned.Frequency range: 3KHz- 1 GH AM and FM radios and cordless phones use radiowaves for transmission further categorized as i) Terrestrial and ii) Satellite 
  2. Microwaves :- It is a line of sight transmission i.e.,the sending and receiving antennas need to be properly aligned with each other.the distance covered by the signal is directly proportional to the height of the antenna. frequency range: 1 GHz-300GHz. These are majorly used for mobile phone, communication and television distribution.
  3. Infrared :- infrared waves are used for very short distance communication.that cannot penetrate through obstacles.this prevents interference between system.frequency range: 300GHz-400THz. It is used in TV remotes.wireless mouse, keyboard,printer,etc.



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