NEB Grade 12 Computer Science Important Question with Solution-Data communication and Networking

Data communication and Networking

Describe ‘simplex’, ‘half duplex’, and ‘full duplex’ with diagram.

• Simplex communication is a one-way communication mode, where data can only be transmitted in one direction, example is a radio broadcast.
• Half duplex communication is a two-way communication mode, but data can only be transmitted in one direction at a time, example is walkie-talkies.
• Full duplex communication allows for two-way simultaneous communication, example is phone calls.
• Simplex communication mode has the advantage of reduced complexity but the disadvantage of no feedback or acknowledgment.
• Full duplex communication mode has the advantage of high-bandwidth communication but the disadvantage of higher cost and complexity.

What is networking? Distinguish between star topology, bus topology and ring topology with the help of a clean diagram.

Networking refers to the connections and communication between computers, devices, and networks. This can include local area networks (LANs), wide area networks (WANs), and the internet. Networking allows devices to share resources, exchange data, and communicate with each other. It can also allow for remote access and control of devices and enable the sharing of internet connections. There are many different types of networks, such as wired and wireless, and various protocols and technologies used to facilitate communication and data transfer.

What do you mean by transmission media? Write short notes on UTP cable, STP, and fiber optical cable.

Transmission media refers to the physical path through which data is transmitted from one device to another. There are several types of transmission media, including wired and wireless.

UTP (Unshielded Twisted Pair) cable: This is a type of cable that is made up of multiple pairs of wires that are twisted together to reduce interference. It is commonly used for telephone lines, Ethernet networks, and other types of data transmission. UTP cables are relatively inexpensive and easy to install but are also more susceptible to interference.

STP (Shielded Twisted Pair) cable: This is similar to UTP cable, but it has an additional layer of shielding around each pair of wires to provide better protection against electromagnetic interference (EMI). STP cables are more expensive than UTP cables and are typically used in environments where EMI is a concern.

Fiber Optic cable: These cables are made of glass or plastic fibers that transmit data in the form of light. They are immune to electromagnetic interference and can transmit data over much longer distances than UTP or STP cables. Fiber optic cables are also more expensive to install and maintain than UTP or STP cables. They are commonly used in high-speed and long-distance data transmission applications, such as internet service providers and cable TV providers.

Describe the ‘Coaxial cable’ and ‘Satellite’ with examples.

Coaxial Cable: Coaxial cable, also known as "coax," is a type of cable that consists of an inner conductor surrounded by a tubular insulating layer, which is surrounded by a braided or foil shield and an outer insulating layer. Coaxial cables are commonly used for cable television, internet, and other forms of data transmission. They are able to transmit high-frequency signals over long distances and are relatively resistant to interference. An example of a coaxial cable is the cable used to connect a cable modem to a cable TV service provider.

Satellite: A satellite is a device that is sent into orbit around the Earth, and is used for communication or navigation purposes. They can be used to transmit or receive data, voice, and video signals. There are two main types of satellites: geostationary satellites and low Earth orbit satellites.

• Geostationary satellites are located at a fixed point in the sky and are mainly used for television and radio broadcasting, and weather forecasting.
• Low Earth orbit (LEO) satellites are located at a lower altitude and are mainly used for communication and internet services, Global positioning system (GPS) and weather forecasting.

Define computer network. Explain the advantages and disadvantages of networking.

A computer network is a collection of interconnected devices, such as computers, servers, and routers, that are connected together to share resources and exchange data. Computer networks can be used for a variety of purposes, including communication, file sharing, and access to remote resources.

Advantages of networking include:

1. Resource sharing: Users on a network can share resources, such as printers, scanners, and storage devices, which can be more cost-effective than having to purchase separate devices for each user.
2. Communication: Users on a network can communicate with each other through various means, including email, instant messaging, and video conferencing.
3. Remote access: Users can access resources and files on a network from remote locations, which can be useful for telecommuting or working from different locations.
4. Backup and security: Networked computers can be backed up regularly, and the network can be secured against unauthorized access and data breaches.
5. Improved performance: Networking can improve the performance of certain applications and tasks, such as data transfer and processing.

Disadvantages of networking include:

1. Security risks: Networked computers are more vulnerable to security threats, such as hacking, viruses, and malware.
2. Maintenance and troubleshooting: Networked computers require regular maintenance and troubleshooting, which can be time-consuming and costly.
3. Complexity: Networked computers can be complex to set up and manage, especially for larger networks or networks with multiple devices and protocols.
4. Dependency: if the network goes down, it can cause disruption to the entire organization, leading to lost productivity and revenue.
5. Cost: setting up and maintaining a network can be expensive, especially for large or complex networks.

Explain about 7 layers of the OSI reference model of networking.

Ans: The OSI (Open Systems Interconnection) reference model is a framework used to understand how data is transmitted between devices on a computer network. It consists of seven layers, each with a specific function and purpose. The layers are:

1. Physical Layer: This is the lowest layer of the OSI model, and it is responsible for the physical transmission of data over the network. It defines the electrical, mechanical, and functional characteristics of the interface between the computer and the network.
2. Data Link Layer: This layer is responsible for creating a reliable link between two devices on the same network. It controls the flow of data between devices, ensuring that data packets are delivered correctly and in the correct order.
3. Network Layer: This layer is responsible for routing data packets across the network. It determines the best path for data to travel and ensures that packets are delivered to the correct destination.
4. Transport Layer: This layer ensures that data is delivered reliably between devices. It is responsible for creating a logical connection between devices, handling error checking and recovery, and controlling the flow of data to prevent overloading.
5. Session Layer: This layer is responsible for creating, managing, and terminating sessions between devices. It manages the communication channels between devices and ensures that data is exchanged correctly.
6. Presentation Layer: This layer is responsible for translating data into a format that can be understood by the application layer. It handles data compression, encryption, and other data conversions.
7. Application Layer: This is the highest layer of the OSI model, and it is responsible for providing a user interface for network services. It provides the interface between the network and the applications that use the network.

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The OSI model is a theoretical framework, and not all the layers are present in all networking protocols, but it helps to understand the different functionality and responsibilities of each layer. The OSI model is also a reference model and not a strict standard, it is used to describe and understand how different networking protocols work and to explain how different layers interact with each other.