Chapter One Class VII

Chapter  One

Computer Networks

Answer the Questions

Q1. Define a computer network. List its three advantages and disadvantages.

Ans: It is an interconnected system of two or more computers and other hardware devices by some communication channel.

Three advantages of computer network are:

•             Speed
•             Information sharing
•             Cost effective

Three disadvantages of computer network are:

•             Security issues
•             Dependency on server
•             Rapid spread of computer viruses

Q2. How is the Internet different from the intranet?

Internet It is the largest network that connects millions of computers worldwide to share information and services.

Intranet It is a private computer network owned by a company or an organization and is accessible only to its employees.

Q3. Explain different types of computer networks.

Ans: Four different types of computer networks are PAN, LAN, MAN, WAN.

•       PAN (Personal Area Network) is the smallest possible network intended for one person.
•        LAN (Local Area Network) is a network that covers a relatively small area such as residence, a building or a campus.
•        MAN (Metropolitan Area Network) is a network that is formed by connecting multiple LANs.
•        WAN (Wide Area Network) is a network that spans a large geographical area such as several cities or even countries.

Q4. What is meant by data transmission media? Differentiate between guided and unguided media.

Ans: Data transmission media refers to the medium used for transmitting data among the devices connected in a network. It can be guided or unguided.

Difference between guided and unguided media is

Guided Media A guided media is also called wired media provides a physical path between the communicating devise in a network Examples are: Twisted pair cable, Coaxial Cable, Fibre optic cable

Unguided Media An unguided media is also called wireless media is a type of transmission media that sends or receives the data through air or space. Examples are: Radio Waves, Microwaves, Infrared, Bluetooth, Wi-Fi

Q5. Define the network topology? Briefly describe the different types of topologies.

Ans: Network topology refers to the way in which the network components (cables, computers and other peripheral devices) are connected together in a network.

Different topologies are Bus, Star and Ring.

•        Bus topology: In this topology the computers and other devices are connected to a single cable called the bus or backbone.
•        Star topology: In this topology the workstations are not directly connected to each other, rather they are connected to a centralized network device known as hub or switch.
•        Ring topology: In this topology the computers and other devices are connected to each other in such a way that they form a closed loop or ring.

Q6. Write short notes on the following.

Modem, Hub, NIC

Ans:

Modem:  A modem (an acronym of modulator/demodulator) is a device that enables a computer to transmit data over telephone line. The job of a modem is to convert data from digital to analog format and vice versa.

Hub: A hub is a small rectangular device that connects multiple devices on a network so that they can communicate with one another.

NIC: The Network Interface Card, commonly referred to as Ethernet card, is a hardware device that enables a computer to connect to a network.