CBSE Class 12 Informatics Practices Introduction to Computer Networks Assignment

Question. How to enable/disable cookie in Google Chrome?
Answer: Click on Triple Dots available at right top side -> Setting -> Privacy and setting -> Site setting – > cookies and site data -> Allow / Block cookie. Explore by doing settings in browser.
Similar type of settings may be changed in other browsers.

Question. What are the types of cookies?
Answer: Session cookies – memorizes your online activities.
Persistent cookies/first-party cookies – tracks your online preferences.
Third-party cookies – collects data based on your online behaviour.

Question. How to change the setting of Google Chrome Browser?
Answer: Click on Triple Dots available at right top side -> Setting -> and refer various type of settings
Similar type of settings may be changed in other browsers.

Question. What is a web server. Give examples of some web servers?
Answer: Web Server –
Web server is a computer where the web content is stored. Basically web server is used to host the web sites and deliver the resources requested through web browser. In more technical term it is a program that uses HTTP for serving files that create web pages for users in response to their requests that are sent by the HTTP clients of their computer is called a web server.
Examples of web servers:
Apache web server
IIS –Internet information services by Microsoft
• Apache Tomcat
• Lighthttpd

Question. Differentiate Static and Dynamic web page.
Answer: 

Question. Explain the different functions performed by web server.
Answer: Functions of a Web Server –
Stores and secures website data
Provides web database access
Serve the end user requests
Bandwidth controlling to regulate network traffic
Virtual hosting.
Server side web scripting

Question. What is web Hosting? Explain different types of web hosting?
Answer: Web hosting is the place where all the files of your website live. It is like the home of our website where it actually lives. A good way to think about this is if the domain name is the address of our house, then web hosting is the actual house that address points to. All websites on the internet, need web hosting.
There are four main types of web hosting:
• Shared hosting – share by multiple domains/web sites.
• VPS (virtual private server) hosting – The main server is split into multiple virtual servers—hence the name. These virtual servers can be customized by individual websites.
• Dedicated hosting – Websites being hosted on a dedicated server have complete technical control over the server settings. We choose the software, configurations, and anything else we need.
• Cloud hosting – Cloud hosting plans come with multiple remote servers. Each server has different responsibilities. If one of the servers is compromised or has a problem, the other servers on the network will take over those responsibilities and pick up the slack.
• Reseller hosting and WordPress hosting are also specific types of hosting

Question. Uplifting Skills Hub India is a knowledge and skill community which has an aim to uplift the standard of knowledge and skills in the society. It is planning to set-up its training centers in multiple towns and villages pan India with its head offices in the nearest cities. They have created a model of their network with a city, a town and 3 villages as follows. As a network consultant, you have to suggest the best network related solutions for their issues/problems raised in (i) to (iv) keeping in mind the distances between various locations and other given parameters.

NOTE : In Villages, there are community centers, in which one room has been given as training center to this organisation to install computers. The organisation has got financial support from the government and top IT companies
i. Suggest a most suitable cable layout for the above connections.
ii. Suggest the most appropriate topology of the connection between the wings.
Answer: i.

Question. Freshminds University of India is starting its first campus Anna Nagar of South India with its centre admission office in Kolkata. The university has three major blocks comprising of Office Block, Science Block and Commerce Block in the 5 km area campus.
As a network expert, you need to suggest the network plan as per (a) to (e) to the authorities keeping in mind the distance and other given parameters.

a. Suggest the authorities, the cable layout amongst various blocks inside university campus for connecting the blocks
b. Suggest the most appropriate topology of the connection between the wings
Answer: 

Question. Vidya Senior Secondary Public School in Nainital is setting up the network between its different wings. There are 4 wings named as SENIOR(S), JUNIOR(J), ADMIN(A) and HOSTEL(H). Distance between various wings are given below:

a. Suggest a suitable Topology for networking the computers of all wings.
b. Suggest the authorities, the cable layout amongst various blocks inside university campus for connecting the blocks
Answer: 

b. Star Topology

Question. The university is planning to connect its admission office in Delhi, which is more than 1250km from university. Which type of network out of LAN, MAN, or WAN will be formed? Justify your answer.
Answer: WAN as its large area

Question. Two universities in different States want to transfer information. Which type of network they need to use for this?
Answer: WAN

Question. Draw a network layout of star topology and bus topology connecting five computers.
Answer: 

Question. Differentiate between Star Topology and Bus Topology. What are the advantages and disadvantages of Star Topology over Bus Topology?
Answer: 1. A star topology is a topology for a Local Area Network (LAN) in which all nodes are individually connected to a central connection point, like a hub or a switch
2. A bus topology is a topology for a Local Area Network (LAN) in which all the nodes are connected to a single cable.
Advantages and disadvantages of Star Topology over Bus Topology:
Advantage Easy to manage from one point – the switch Easy to add and remove nodes Durable
Disadvantage
• Requires specialist network hardware (the switch)
• Makes the network reliant on the switch’s performance
• A finite number of switch ports limits the network’s size

Question. The university is planning to connect its admission center in the closest big city which is more than 350 KM from the University. Which type of network out of LAN, MAN, WAN will be formed? Justify your answer.
Answer: MAN

Question. In above Question No.3. Suggest the topology of the network for efficiently connecting each computer installed in each of the buildings out of the following: (Bus, Star Topology)
Answer: Star Topology

Question. The organization is planning to connect its new office in Delhi, which is more than 1250 km current location. Which type of network out of LAN, MAN, or WAN will be formed? Justify your answer – WAN
Answer: WAN as area is large

Question. Daniel has to share the data among various computers of his two offices branches situated in the same city. Name the network (out of LAN, WAN, PAN and MAN) which is being formed in this process
Answer: LAN

Question. Write the name of topology in which all the nodes are connected through a single Coaxial cable?
Answer: Bus Topology

Question. Which of the following Cabling technique is considered best between buildings for establishing LAN? – (Ethernet, Telephone, Optical fiber, Co-axial) – Ans Ethernet
Answer: Ethernet

Computer Network Notes for Class 12 Informatics Practices

Definition - A system connecting two or more interconnected computers and digital devices is called a computer network. These computers can exchange electronic information among themselves and are connected to each other by wire or wireless. This traffic of information takes place, which is called protocol. When many networks are connected together, they are called Internetwork, whose short form Internet (Antarjaal, Internet) is quite popular.

- Analog and digital methods are used to exchange information. Network components are known as devices such as wires, hubs, switches, routers, etc. The influence of wireless networks is increasing in computer networking. Computer networks are used in electronic communication. Through this, the process of sending information from one place to another is called telecommunication. Sending or receiving data/information between one or more computers and different types of terminals is called a computer network.

Computer Network
- Computer network refers to the joining of two or more computers.
- An area created by connecting two or more computers or devices is called a computer network.
- Data and information are exchanged through computer networks.
- Data, instructions, files, etc. are sent from one computer to another through the network.
- Maximum use of minimum number of devices can be done through computer network.
- Computer network was started in the year 1969 in America.
- Initially, the computer network was named ARPANET.
- ARPANET – Advance Research Project Agency Network
- Shares data and hardware from one computer to another through a computer network.
- To send and receive data or information on the network like computer, printer etc. are connected to the node, and the link connecting the nodes is called communication channel.

Benefits and Features of Computer Network –
- It is confined to one room or one building.
- Its data transfer speed is high.
- It does not have to rent an external network.
- Data remains secure in this.
- It is easy to organize data.

Use of Computer Networks
- There are many advantages of connecting computer systems and their devices through a network –
- With this we can exchange information through E-mail (Electronic mail).
- Receive and share information using the Web or the Internet.
- It does resource sharing. Such as printer devices and storage devices.
- Video conferencing.
- Using notebook computer and mobile phone.
- types of computer networks
- In a computer network, each computer and other device is connected to another device, but there are many ways and mediums to connect it. Therefore, considering the geographical areas as the basis, the computer network has been divided into several parts, such as –
1. LAN
2. MAN
3.WAN

1. LAN (Local Area Network): -
Computer networks are divided on the basis of geographical area, in which the smallest area is called LAN.
Two or more computer networks connected in a limited geographical area are called Local Area Networks.
Its area can be about 1 kilometer.
Example – A small network used in a building, an office, university, home, school, hospital etc. is a LAN.

2. MAN (Metropolitan Area Network) :-
If two or more computers or two or more networks are connected in an urban geographical area, then the network formed is called Metro Area Network.
For example, connecting computer networks installed at two different places in the city of an organization together is called MAN.

3.WAN (Wide Area Network):-
- A computer network spread over a wide or vast geographical area is called a wide area network, in which networks located thousands of kilometers away can be connected.
WAN is the largest network of computer network.
In this network communication satellites, signals etc. are used due to long distance.

Other Networks –

PAN (Personal Area Network) :-
Nowadays, along with computer, the trend of network is increasing in other devices as well, such networks which connect two devices in a limited area on the basis of personal area are called personal area network.
For example – wireless signal, Bluetooth, Wi-Fi etc.

Networking Device :-
- When two or more devices are connected to each other in a computer network, the device is called a networking device.

1. NIC (Network Interface Card)
Network interface card helps in physically connecting the computer. This card is connected to the motherboard and I / O on each computer.
It is also called LAN card, network adapter, Ethernet card.

2. HUB :-
Hub is a networking device through which the computers present in the local area are connected together.
There are many ports in the hub which work to connect the devices.
Data packets received on one port in the hub can be used from other ports as well.

3.Switch :-
Switch is also a hardware networking device, through which computers and devices of the network are connected. Switch and Hub are used in almost the same way but through the switch the data is sent only to the destination (computer).

4.Bridge :-
- A bridge is used to connect two networks having the same protocol.

5.Router :- Router is used to connect two or more networks. Through this the information reaches its destination. Router also uses routing table in which information is kept.
Routers operate at the network layer of the OSI model.

6.Gateway :-
Networks having two or more different protocols are connected by a gateway.

7.Repeter :-
Through this networking device, the signal is speeded up, that is, the low level signal is made into a high level and added.

RJ-45 Connector –
RJ-45 connector is used on network interface card or network port in computer system.
RJ-45 connector is used to connect computer in local area network.
It has eight pins to which eight wires are attached.
Duplex Channel

Communication Channels :-
The communication medium between two devices is called a duplex channel. These are of the following three types-
1. Simplex Channel:- In this method the data always flows in one direction. Like - radio, keyboard etc.
2. Half Duplex Channel:- In this method data flows in both directions but data flows in only one direction at a time. Like – Telephone, Walkie-Talkie, Bluetooth etc.
3.Full Duplex Channel:- In this channel the data flow in both directions at a time. For example – Wi-Fi, online messaging etc.

Computer Communication:-

The exchange of data and information from one computer to another is called data communication. In today's era of information technology, work can be done easily by sitting at home by connecting to computer and internet. Like:- railway reservation, hotel reservation, air travel ticket, we can easily get all these computer network at home. And it has become possible only because of computer communication.

If we learn about data communication in some simple words, its definition is as follows: Data transaction between any two devices is called data communication.

Sender:- The one who sends the data is called Sender. Which can also be called the source from where the data is generated.

Receiver: - Receives or receives the data sent by the sender, it is called receiver or destination.

Transmission Medium: - The way or the device with the help of which the sender sends the data to the receiver.

- Transmission Media When the sender and the receiver of the message send the data from one place to another, they use some medium or the other. These mediums are of two types-
1. By wire
2. By wireless.

1. By cable: - In this medium, data is sent from one device to another using wire or cable, in this the following cables are used like –
1. Twisted Pair Cable
2. coaxial cable
3. Optical Fiber Cable

1. Twisted Pair Cable
Twisted Pair Cable is such a wire in which two wires are twisted with each other. In this cable there are 4 Pairs inside the plastic and 2 wires are wrapped from 1 pair and all have different color codes. This is the most commonly used cable in LAN network.

Twisted Pair Cable is of 2 types–

1. UTP (Unshielded Twisted Pair) This is Un-Shielded Twisted Pair Cable, meaning there is no separate shielding or cover in it as you can see in UTP cable. These cables can generally transfer data from 1GBps to 10GBps up to 100 meters.

2. STP (Shielded Twisted Pair) – This is Shielded Twisted Pair Cable. There is an additional shield in this cable, due to which the data becomes secure in it and the speed of data transfer also increases.
- The benefits or advantages of Twisted pair Cable which are given below-
- These cables are cheaper as compared to other cables.
- Its installation is quite simple.
- Through this it is very easy to connect any device to the network.
- Coaxial Cable

- Coaxial cable has a main copper wire called core. There is a layer of insulation over the copper wire and over it the copper mesh. Its data transfer distance is up to 185 meters. Installation of Coaxial Cable is easy but it is very flexible and weak due to which there was more fear of breaking it. The axial cable is mainly used in Bus Topology.

There are two types of coaxial cable.
1. Thinnet 2. Thiknet
1. Thinnet – It is widely used because it is cheap, flexible and easy to use.
2. Thicknet – This cable is thick which cannot be bent easily, it is used in TV cable etc.
- Secure transmission of data.
- Protecting data from cross talk.

Optical Fiber Cable
- This cable is made of glass. Fiber Optic Cable has revolutionized the world of Internet. Today all the countries are connected to each other through internet, in which fiber optic cable plays a big role. Fiber Optic Cable is an advanced transmission media which is used to transmit data at high speed and over long distances.

- Fiber Optic Cable is the fastest data transfer cable in the world of networking, so it is used more in submarine communications, meaning the use of Fiber Optic Cable to connect the network of one country to the network of another country. are done. In this cable, DATA travels in the from of the Light signal and gets converted from Light signal to Digital signal as soon as it reaches the Data Destination.

- The speed of data communication in this cable is 100 megabytes per second to 2 gigabytes per second.
Transmitting more and safer data than copper cable
High data transmission rate
Long distance data transmission
Safest way of cable submission

- Wireless Media

- Through this medium, data is sent from one device to another without cables i.e. by signals.

- Wireless Transmission Media: - The use of wire without wire for the transaction of data from one computer to another is called wireless. In this, using a signal, one computer is connected to another computer. Many mediums are used in this.

- Radio Wave: - This wave is used to transmit data over long distances. It also easily crosses tall buildings or other obstructions. This signal can travel in all directions. In this, it is not necessary for the sender and the receiver of the data to be on the same line. In radio broadcasting, data can be transmitted at high speed using VHF, UHF and SHF.

- Micro Wave Transmission (Micro Wave Signal):- In this, radio waves of high frequency are used. Places where cable access is difficult. There this signal can be easily used. These microwave signals are signals that move in a straight line, that is, if there is an obstruction between the transmitter and the receiver, the signal cannot travel from one place to another. That's why mostly their towers are installed at high places. If there is a decrease in these signals, then generally repeaters are installed at a distance of 25 to 30 kilometers. These repeaters amplify the signals. Microwave transmissions are mostly used in long distance telephone, communication, transmission of phone, TV etc. This signal becomes weak due to bad weather etc.

- Satellite Transmission (Satellite Signals) :- Only micro waves are used in satellite signals but there is no problem of straight line in it. This communication satellite is established in an orbit at an altitude of 36 thousand kilometers from the equator. In this, the communication satellite itself can be considered as a microwave relay station. Due to which the transmitting and receiving station can receive the signals from any place on the earth. In this transmission, signals of 6 GHz frequency are sent from the Earth to the satellites in space. Due to the long distance, these signals become weak, so the signals are made stronger by using transponders. In this way, different frequencies are used for sending and receiving signals to satellites. This signal is used for extremely long distance such as telephone communication, television programs, international communication etc.

- Infrared Signal :- It is used for the transaction of data in short distance. Infrared rays are used in this. These rays work on high frequency. Like - T.V. Operate by remote.

- Bluetooth: - This is also an easy way to connect different devices without wires. In which the bluetooth signal is used. For example, it is used to connect computer, mobile, table, laptop, printer, digital camera, video game etc.

- WiFi: – Its full name is Wire Less Fidelity. WiFi Alliance is a trade mark of the company. Through this, the local area network is connected without cables.
This creates a wireless network. Which is based on IEEE. The radio waves used for WiFi communication are similar to cell phones and radios. Their frequency ranges from 2. 4 GHz to 5 GHz. Which is much faster than the frequency of the cell phone. The 802. 11 networking standard is used in WiFi communication.

Form of Data Transmission :- Electrical signal is used in data transmission. These are of two types-
1. Analog
2. Digital

1. Analog:- These signals keep on changing continuously with respect to time. These signals move from low to high. For example, telephone system is an example of analog data transmission.

2. Digital: - These signals are discrete in which data is transmitted in the state of on and off.

- Topology :-
The physical structure or physical layout of the network is called topology.
The way of connecting computers in a network is called topology.

These are of the following types -
1. Bus
2. Ring
3. Star
4. Mesh
5. Hybrid

1. Bus Topology:-
- In this topology, all the devices or computers of the network are connected through a single cable. This topology is used for limited area. Ethernet devices can be used in this.

2. Ring Topology:-
- In this topology the first computer is connected to the second and in the same way other computers are connected. When the last computer connects to the first computer, it forms a ring-like structure, hence it is called ring topology. Token passing system is used in this topology. In this topology, data moves in one direction.

3. Star Topology:-
- In this topology, there is an intermediate networking device or computer that transmits data from one device to another in the middle of the computer in the network.

4. Mesh Topology:-
- In this topology, all the devices and computers present in the network are directly connected to each other. All computers are directly connected to each other.

5. Hybrid Topology:-
- In this topology, more than one topology is combined together, hence it is called hybrid topology.

Server-Client Form :-
- Server: - The main computer in the network is called server on which the data is stored and it responds to the request received from the client.
- Client: - All the computers of the network to which the user is connected are called clients. On which the work of input output is done.