Introduction to Computer Networks

Write two advantages and disadvantages of networks.

Answer

Two advantages of networks are:

1. It allows sharing of resources like printers, scanners.
2. It allows sharing of storage i.e., files can be shared over a network.

Two disadvantages of networks are:

1. If networks are badly managed, services can become unusable and productivity falls.
2. If software and files are held centrally, it may be impossible to carry out any work if the central server fails.

What is meant by topology ? Name some popular topologies.

Answer

The pattern of interconnection of nodes in a network is called the Topology.

The most popular topologies are as follows:

1. Bus or Linear topology
2. Ring or Circular topology
3. Star topology
4. Tree topology
5. Mesh topology
6. Fully connected topology

What are the factors that must be considered before making a choice for the topology ?

Answer

The factors that must be considered before making a choice for the topology are as follows:

1. Cruciality of Work — How crucial the continuity of work is a very important factor. For instance, military networks must not fail at any cost thus fully connected topology is preferred for military networks.
2. Cost — Keeping in mind the budget, we should decide about a topology. A linear bus topology network may be the least expensive way to install a network. Fully connected is the most expensive way of creating a network.
3. Length of cable needed — Sometimes, length of cable must be saved. The linear bus topology network uses shorter lengths of cable.
4. Future growth — If a network has to grow in future, then the topology must support expansion. With a star topology, expanding a network is easily done by adding another concentrator.
5. Communication Media — Sometimes, difficult terrains like hilly areas do not allow use of regular cables. For such conditions, linear bus topologies are not possible. The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.

What are the similarities and differences between bus and tree topologies ?

Answer

Similarities

1. Transmission can be done in both the directions, and can be received by all other stations.
2. There is no need to remove packets from the medium.

Differences

1. Tree topology is a network with the shape of an inverted tree with the central root branching and sub-branching to the extremities of the network whereas in bus topology, all devices on network are connected to a single continuous cable called a bus.
2. Tree topology is expensive and difficult to maintain as compared to Bus Topology.

How is a PAN different from a LAN ?

Answer

What is NIC ?

Answer

NIC (Network Interface Card) is a network adapter that acts as an interface between computer and the network.

Give two advantages and two disadvantages of Star topology.

Answer

The two advantages of star topology are:

1. Ease of service: The star topology has a number of concentration points (where connections are joined). These provide easy access for service or reconfiguration of the network.

2. One device per connection: In star topology, failure of a single connection involves disconnecting one node from an otherwise fully functional network.

The two disadvantages of star topology are:

1. Long cable length: Because each node is directly connected to the center, the star topology necessitates a large quantity of cable.

2. Central node dependency: If the central node in a star network fails, the entire network is rendered inoperable. This introduces heavy reliability and redundancy constraints on this node.

Give two advantages and two disadvantages of tree topology.

Answer

Two advantages of tree topology are:

1. It uses point-to-point wiring for individual segments.
2. It is supported by several hardware and software vendors.

Two disadvantages of tree topology are:

1. Overall length of each segment is limited by the type of cabling used.
2. If the backbone line breaks, the entire segment goes down.

Give two advantages and two disadvantages of bus topology.

Answer

The two advantages of bus topology in a network are:

1. It requires shorter cable length and has a simple wiring layout.
2. It provides a resilient architecture making it very reliable from a hardware point of view.

The two disadvantages of bus topology in a network are:

1. Fault diagnosis and isolation is difficult.
2. Reconfiguration is required when the network has its backbone extended using repeaters.

What is a modem ? Name two categories of modems.

Answer

Modem stands for Modulator DEModulator. It is a computer peripheral device that allows us to connect and communicate with other computers via telephone lines.

Modems come in two varieties :

1. Internal modems — They are fixed within the computer.
2. External modems — They are connected externally to a computer as other peripherals are connected.

Define hub.

Answer

A hub is a networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together.

Define switch.

Answer

A switch is a device that is used to segment networks into different sub-networks, called subnets or LAN segments.

Define repeater.

Answer

A repeater is a network device that amplifies and restores signals for long-distance transmission.

Define bridge.

Answer

A bridge is a device that links two networks together. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. Bridges can handle networks that follow same protocols.

Define router.

Answer

A router is a network device that forwards data from one network to another. A router works like a bridge but can handle different protocols.

Define gateway.

Answer

A gateway is a network device that connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely different structures.

Two devices are in network if

1. a process in one device is able to exchange information with a process in another device
2. a process is running on both devices
3. the processes running of different devices are of same type
4. none of the mentioned

Answer

a process in one device is able to exchange information with a process in another device

Reason — A computer network is a collection of interconnected autonomous computing device, so as to exchange information and­ share resources.

What is a standalone computer ?

1. A computer that is not connected to a network
2. A computer that is being used as a server
3. A computer that does not have any peripherals attached to it
4. A computer that is used by only one person

Answer

A computer that is not connected to a network

Reason — A computer that is not connected to a network is a stand alone computer.

Central Computer which is powerful than other computers in the network is called as ...............

1. Client
2. Server
3. Hub
4. Switch

Answer

Server

Reason — A computer that facilitates the sharing of data, software, and hardware resources on the network, is called a Server.

Television cable network is an example of :

1. LAN
2. WAN
3. MAN
4. Internet

Answer

MAN

Reason — A television cable network is an example of a MAN (Metropolitan Area Network) because it covers a city or large area, typically up to 30-40 km.

Which of the following topologies needs least cable lengths ?

1. Star
2. Tree
3. Bus
4. None of these

Answer

Bus

Reason — Bus topology requires the least cable length because there is a single common data path connecting all nodes.

Which of these components is internal to a computer and is required to connect the computer to a network ?

1. Wireless Access Point
2. Network Interface card
3. Switch
4. Hub

Answer

Network Interface card

Reason — Each workstation needs an NIC (Network Interface card) to help establish a connection with the network because without this, the workstations will not be able to share network resources.

Hub is a

1. Broadcast device
2. Unicast device
3. Multicast device
4. None of these

Answer

Broadcast device

Reason — A hub is a networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together.

Switch is a

1. Broadcast device
2. Unicast device
3. Multicast device
4. None of these

Answer

Unicast device

Reason — Switch is a unicast device because it forwards data packets specifically to the intended device connected to it by using the device's MAC address.

The device that can operate in place of a hub is a :

1. Switch
2. Bridge
3. Router
4. Gateway

Answer

Switch

Reason — A switch can operate in place of a hub because it connects multiple devices within a network and forwards data only to the specific device that needs it.

A repeater takes a weak and corrupted signal and ............... it.

1. Amplifies
2. Regenerates
3. Resembles
4. Reroutes

Answer

Regenerates

Reason — A repeater is a network device that electrically regenerates a weak or corrupted signal to restore its strength and quality, enabling it to travel long distances.

Which network topology requires a central controller or hub?

1. Star
2. Bus
3. Mesh
4. Tree

Answer

Star

Reason — Star topology consists of a central node to which all other nodes are connected by a single path.

Which topology requires a multi-point connection on a single cable?

1. Star
2. Bus
3. Mesh
4. Tree

Answer

Bus

Reason — Bus topology requires a multi-point connection on a single cable as it consists of a single length of transmission medium onto which the various nodes are attached.

Which of the following topologies contains a backbone cable running through the whole length of the network ?

1. Star
2. Bus
3. Mesh
4. Tree

Answer

Bus

Reason — Bus topology contains a backbone cable running through the whole length of the network to which all the nodes are attached.

Which of the following devices can be used at the centre of a star topology ?

1. Router
2. Repeater
3. Modem
4. Hub

Answer

Hub

Reason — A hub can be used at the centre of a star topology as it has multiple ports that are used for connecting multiple computers.

If a computer connected to a star topology fails, the entire network will ...............

1. also fail
2. work unaffectedly
3. only server will work
4. none of these

Answer

work unaffectedly

Reason — Star topology consists of a central node to which all other nodes are connected by a single path. Thus, failure of a single connection typically involves disconnection of one node from an otherwise fully functional network.

A combination of bus and star topologies is called a ............... topology.

1. Combination
2. Hybrid
3. Mesh
4. Tree

Answer

Tree

Reason — The shape of tree topology network is that of an inverted tree with the central root branching and sub-branching to the extremities of the network.

Which of the following topologies is very efficient and all nodes are connected to a central hub?

1. Star
2. Tree
3. Bus
4. Ring

Answer

Star

Reason — The star topology, with its central node connecting all other nodes through a single path, enables easy detection and isolation of faults. In case of a single connection failure, only one node is disconnected, leaving the rest of the network fully functional. Hence, it is an efficient topology.

Internet is an example of ............... topology.

1. Star
2. Bus
3. Mesh
4. Bus

Answer

Mesh

Reason — In a mesh topology, each node is connected to every other node, creating multiple paths for data transmission. Similarly, the internet, being a complex network, features numerous interconnected devices (nodes) that facilitate data exchange and communication.

Data is converted in a form so as to travel over telephone lines using this device.

1. Modem
2. Hub
3. Switch
4. Router

Answer

Modem

Reason — Modems are devices that modulate digital data into analog signals for transmission over telephone lines, and they also demodulate incoming analog signals back into digital data for reception by computers or other digital devices.

Network device that regenerates and retransmits the whole signal is ............... .

1. Modem
2. Hub
3. Repeater
4. Bridge

Answer

Repeater

Reason — A Repeater is a network device that amplifies and regenerates signals for long-distance transmission.

Network device which connects networks of similar types (same protocols).

1. Hub
2. Router
3. Bridge
4. Gateway

Answer

Bridge

Reason — A bridge is a device that links two networks together, which follow same protocols.

Network device which connects dissimilar networks (different protocols).

1. Hub
2. Router
3. Bridge
4. Gateway

Answer

Gateway

Reason — A gateway is a network device that connects dissimilar networks, establishes an intelligent connection between a local network and external networks with completely different structures.

Networks devices that sends the data over optimizing paths through connected hops is

1. Hub
2. Router
3. Bridge
4. Gateway

Answer

Router

Reason — Based on a network road map called a route table, routers can help ensure that packets are traveling the most efficient paths to their destinations.

A ............... is a device that connects the organization's network with the outside world of the Internet.

1. Hub
2. Modem
3. Gateway
4. Repeater

Answer

Gateway

Reason — A gateway is a node on a network that serves as an entrance to another network. In an organization, the gateway is a device that connects the organization's network with the outside world, including the Internet.

A computer network that spans a relatively large geographical area is called WAN.

WAN stands for Wide Area Network.

A computer, part of a computer network is called a node/host.

A network having a span within a building is called a LAN.

A network having a span of city, is called a MAN.

Computers connected by a network across different cities is an example of WAN.

Switch network device is known as an intelligent hub.

The hub is a central connection point where all network cables are concentrated.

The bridge is a network device that can connect the network segments based on the same protocol.

The router is a network device that navigates the data packets over large networks through the most efficient route.

The gateway is a network device that connects dissimilar networks.

The repeater is a networking device that regenerates or recreates a weak signal into its original strength and form.

The bus topology has a central line and all nodes are connected to it.

The star topology has a central controller.

The tree topology is said to be a combination of star and bus topologies.

In mesh topology, there exists multiple paths between any two nodes of the network.

The PAN is a small network created by linking many personal devices.

A switch is networking device that connects computers in a network by using packet switching to receive, and forward data to the destination.

A LAN is connected to large geographical area.

Answer

False

Reason — A LAN is connected to a small geographical area, typically up to 1 km.

A switch can work in place of a hub.

Answer

True

Reason — Both hubs and switches are used to connect multiple devices in a network, switches offer more efficient data transmission compared to hubs. Hence, switch can work in place of hub.

A gateway is like a modem.

Answer

False

Reason — A gateway is not like a modem because it connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely different structures. On the other hand, a modem modulates digital data from the sender computer into analog form to travel over the telephone lines to the target computer and demodulates received analog data into digital form for the target computer.

LAN is the biggest network geographically.

Answer

False

Reason — Wide Area Network (WAN) is the largest network geographically because it spreads across countries or over a very large geographical area, encompassing multiple cities, countries, or continents.

LAN is the smallest network geographically.

Answer

False

Reason — Personal Area Network (PAN) is the smallest network geographically because it operates within the range of an individual person, typically up to 10 meters.

PAN is the smallest network geographically.

Answer

True

Reason — Personal Area Network (PAN) is the smallest network geographically because it operates within the range of an individual person, typically up to 10 meters.

The Internet is an example of WAN.

Answer

True

Reason — A WAN covers a large geographical area across different locations. The internet spans the entire globe, connecting millions of networks and devices worldwide. Therefore, the Internet is an example of a Wide Area Network (WAN).

The bus topology is the simplest topology.

Answer

True

Reason — The bus topology requires short cables and features a simple wiring layout. It provides a resilient architecture, which enhances hardware reliability. Therefore, the bus topology is considered as the simplest network topologies.

The star topology ensures that the network will work even when a node fails.

Answer

True

Reason — In a star topology, each node is connected directly to a central node. If one node fails or its connection is disrupted, it only affects that individual node's connectivity. The rest of the network remains operational because the failure is contained within that specific node's connection.

Amplifier and a repeater do the same thing.

Answer

False

Reason — An amplifier amplifies all incoming signals over the network, including both the signal and any concurrent noise. On the other hand, a repeater is a device that regenerates a signal being transmitted on the network.

A hub broadcasts the received signal to all its connected devices.

Answer

True

Reason — A hub is networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together. Hub broadcasts the message to all nodes in the network, only the target node takes the message while others ignore it.

A switch is an intelligent hub.

Answer

True

Reason — A switch is called as an "intelligent hub" because it can direct data specifically to the intended device connected to it, unlike a hub that just sends data to all connected devices. This makes a switch more efficient for managing network traffic.

Repeater and router precisely do the same thing.

Answer

False

Reason — A repeater is a network device that amplifies and restores signals for long-distance transmission. Whereas a router is a network device that forwards data from one network to another. A router works like a bridge but can handle different protocols. Hence, repeater and router work differently.

A hub can be replaced with a switch.

Answer

True

Reason — A switch can replace a hub in a network. While both hubs and switches are used to connect multiple devices in a network, switches offer more efficient data transmission compared to hubs.

A router can be replaced with a bridge.

Answer

False

Reason — A bridge is a device that connects two networks together and can handle networks that follow the same protocols. On the other hand, a router is a network device that forwards data from one network to another. It functions similarly to a bridge but can handle different protocols. A router differs from a bridge in that the former uses logical addresses, while the latter uses physical addresses.

Assertion. There is a difference between a standalone computer and a computer as a network node.

Reason. A standalone computer needs a special hardware NIC to be a network node.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation
A standalone computer operates independently without being connected to a network, while a computer serving as a network node participates in network communication. To function as a network node, a computer requires a Network Interface Card (NIC) hardware, which facilitates communication over the network.

Assertion. A server is a computer but not every computer is a server.

Reason. A computer having the capabilities to serve the requests of other network nodes is a server.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation
A computer becomes a server when it possesses the capability to fulfill requests from other network nodes. This aligns with the definition of a server. Therefore, a server is a computer, but not all computers serve the same purpose.

Assertion. On a computer network the users work on network nodes only.

Reason. A server cannot act as a network node.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Assertion is true but Reason is false.

Explanation
Users on a computer network interact with various network nodes such as computers, printers, switches, routers, etc., to access resources or services. In a computer network, a server is indeed considered a network node. A network node is any device connected to a network that can communicate with other devices. Servers, which provide services or resources to other devices on the network, are an integral part of network infrastructure and are thus considered network nodes.

Assertion. The tree topology is a hybrid topology created through a combination of Bus and Star topologies.

Reason. In tree topologies, at a time either bus topology transmission is followed or star topology transmission takes place but never both.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Assertion is true but Reason is false.

Explanation
The tree topology is a hybrid topology created through a combination of Bus and Star topologies. In tree topology, transmission takes place in the same way as in the bus topology.

Assertion. The bus and star topologies are widely used topologies.

Reason. Bus topology is the simplest topology and star topology is more robust comparatively.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation
Both the bus and star topologies are widely used in networking. The bus topology requires short cables and features a simple wiring layout. It provides a resilient architecture, which enhances hardware reliability. Therefore, the bus topology is considered as the simplest network topologies. While the star topology is known for its robustness, as it provides easy access for service and better fault tolerance compared to other topologies.

Assertion. MODEM stands for modulator-demodulator.

Reason. It is a computer hardware device that converts data from a digital format to analog and vice versa.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both A and R are true and R is the correct explanation of A.

Explanation
MODEM stands for modulator-demodulator. It is a computer hardware device that allows connecting and communicating with other computers via telephone lines. It converts digital data from a computer into analog signals suitable for transmission over telephone lines, and vice versa, converting incoming analog signals back into digital data that the computer can understand.

Assertion. A modem is a communication device that works on the principle of converting digital data to analog data and vice versa.

Reason. Modulation is a process of converting digital data to analog form and Demodulation is a process of converting analog data to digital form.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation
Modem is a communication device that works on the process of modulation/demodulation. In modulation, digital data of the sender computer is converted in analog form to travel over the telephone lines to the target computer. In demodulation, received analog data is converted back to digital form for the target computer.

Assertion. A hub can also act as an amplifier at times.

Reason. An active hub is capable of amplifying the signal during transmission while a passive hub merely lets the signal pass through it.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation
A hub can also act as an amplifier at times. Hubs can function as either passive or active devices. Active hubs electrically amplify the signal as it moves from one connected device to another. While passive hubs allow the signal to pass from one computer to another without any change.

Assertion. A repeater is not like an amplifier.

Reason. A repeater regenerates a signal thereby removing noise.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation
A repeater is not like an amplifier because a repeater not only amplifies the signal but also performs signal regeneration. When a signal weakens over long distances, the repeater collects the inbound packet and then retransmits it as if it were originating from the source station. This process effectively removes noise.

Assertion. A router and a bridge are similar.

Reason. A router works like a bridge but can handle different protocols unlike bridge.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Assertion is false but Reason is true.

Explanation
A router is a network device that forwards data from one network to another using logical addresses. A router works like a bridge but can handle different protocols. On the other hand, a bridge is a device that links two networks together using physical addresses and can handle networks that follow the same protocols. Hence, a router and a bridge are different.

Assertion. Hubs and switches can be replaced.

Reason. While a hub is a broadcast device, a switch is a unicast device.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R is not the correct explanation of A.
3. A is true but R is false.
4. A is false but R is true.

Answer

Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.

Explanation
Both hubs and switches are used to connect multiple devices in a network. Hence they are replaceable with each other. Switches offer more efficient data transmission compared to hubs because they can direct data specifically to the intended device connected to it, unlike a hub that just sends data to all connected devices. This makes a switch more efficient for managing network traffic. Therefore, a hub is a broadcast device, a switch is a unicast device.

What is a network ? What are its goals and applications ?

Answer

A network is an interconnected collection of autonomous computers that can share and exchange information and resources.

Major goals and applications of networks are :

1. Resource Sharing — Through a network, data, software and hardware resources can be shared irrespective of the physical location of the resources and the user.
2. Reliability — A file can have its copies on two or more computers of the network, so if one of them is unavailable, the other copies could be used. That makes a network more reliable.
3. Reduced Costs — Since resources can be shared, it greatly reduces the costs.
4. Fast communication — With networks, it is possible to exchange information at very fast speeds.

Discuss and compare various types of networks.

Answer

Based on geographical spread, networks can be of four types:

1. LAN (Local Area Network) — Small computer networks that are confined to a localized area such as a building or­ factory, are known as Local Area Networks (LANs). LANs have geographical spread of up to 1 km.

2. WAN (Wide Area Network) — The networks spread across countries or on a very big geographical area are known as WANs. The WANs link computers to facilitate fast and efficient exchange of information at lesser costs and higher speeds. The largest WAN in existence is the Internet.

3. PAN (Personal Area Network) — It is the interconnection of information technology devices within the­ range of an individual person, typically within a range of 10 meters. PAN could also be interconnected without wires to the Internet or other networks.

4. MAN (Metropolitan Area Network) — MAN refers to a network that is spread over an area as big as a city.

Based on component roles, network can be of two types:

1. Peer-to-Peer networks — Computers in peer-to-peer network can act as both servers sharing resources and as clients using the resources. A peer-to-peer network has up to ten computers.

2. Client/Server Networks — Server-based networks provide centralized control of network resources and rely on server computers to provide security and network administration. A client computer requests and utilizes network resources and a server is dedicated to processing client requests. Bigger networks prefer to have this type of network with centralized control.

Explain various mostly used topologies.

Answer

The most used topologies are as follows:

1. Bus or Linear topology — In this topology, all devices on network are connected to a single continuous cable called a bus. Transmission from any station travels the length of the bus in both directions and can be received by all other stations. The destination device, on identifying the address on data packet copies the data onto its disk. When the data packet reaches at either end the terminator on that end absorbs the signal, removing it from the bus. This topology can be used for smaller networks.

2. Ring Topology — In this topology, each node is connected to two and only two neighboring nodes. Data is accepted from one of the neighboring nodes and is transmitted onwards to another. Thus data travels in one direction only, from node to node around the ring. After passing through each node, it returns to the sending node, which removes it.

3. Star Topology — In this topology each workstation is directly linked to a central node. Devices can be easily plugged or unplugged to the central node, as need dictates. Any communication between the stations must pass through the central node.

4. Tree Topology — In this topology the network is shaped as an inverted tree with the central root branching and sub-branching to the extremities of the network. Transmission in this topology takes place in the same way as in bus topology.

5. Mesh topology — In this topology, each node is connected to more than one node to provide an alternative route in the case the host is either down or too busy.

6. Fully Connected topology — When in a network each host is connected to other directly i.e., there is a direct link between each host, then the network is said to be fully connected. This characteristic is termed as full connectivity.

Discuss the factors that govern the selection of a topology for a network.

Answer

The factors that govern the selection of a topology for a network are as follows:

1. Cruciality of Work — How crucial the continuity of work is a very important factor. For instance, military networks must not fail at any cost thus fully connected topology is preferred for military networks.

2. Cost — Keeping in mind the budget, the topology should be decided based on cost. A linear bus topology network may be the least expensive way to install a network. Fully connected is the most expensive way of creating a network.

3. Length of cable needed — Sometimes, length of cable must be saved. The linear bus topology network uses shorter lengths of cable.

4. Future growth — If a network has to grow in future, then the topology must support expansion. With a star topology, expanding a network is easily done by adding another concentrator.

5. Communication Media — Sometimes, difficult terrains like hilly areas do not allow use of regular cables. For such conditions, linear bus topologies are not possible. The most common cable in schools is unshielded twisted pair, which is most often used with star topologies.

Which of the following is not a network topology : Star, Mesh, Tree, Bug, Bus ?

Answer

"Bug" is not a recognized network topology, while "Star," "Mesh," "Tree," and "Bus" are commonly known and used network topologies in computer networking.

Compare and contrast Star and Bus topologies.

Answer

Compare and contrast Star and Tree topologies.

Answer

Compare and contrast Bus and Ring topologies.

Answer

What is the role of modem in electronic communications ?

Answer

Modem stands for Modulator Demodulator. It is a computer peripheral that connects a workstation to other work-stations via telephone lines and facilitates communications. It converts digital signals to audio frequency tones which are in the frequency range that the telephone lines can transmit and it can also convert transmitted tones back to digital information.

Give examples of any two network devices.

Answer

Modem and Switch are two examples of network devices.

What is hub ? What are its types ?

Answer

A hub is networking device having multiple ports that are used for connecting multiple computers or segments of a LAN together.

Hubs are of two types:

1. Active hubs — They electrically amplify the signal as it moves from one connected device to another. Active concentrators are used like repeaters to extend the length of a network.

2. Passive hubs — They allow the signal to pass from one computer to another without any change.

What is the role of a switch in a network ?

Answer

A switch is a device that is used to segment networks into different sub-networks, called subnets or LAN segments to prevent traffic overloading.

A switch is responsible for filtering i.e., transforming data in a specific way and for forwarding packets between LAN segments. To insulate the transmission from the other ports, the switch establishes a temporary connection between source and destination and then terminates the connection once the conversation is done.

Briefly discuss the role of a repeater in networking.

Answer

A repeater is a network device that amplifies and restores signals for long-distance transmission. It is used in long network lines, which exceed the maximum rated distance for a single run.
Over distance, the cables connecting a network lose the signal transmitted. Repeaters are installed along the way in the network to ensure that data packets reach their destination without any degradation of the message.

Briefly discuss the role of a router in networking.

Answer

A router is a network device that forwards data from one network to another. A router works like a bridge but can handle different protocols. Based on a network road map called a routing table, routers can help ensure that packets are traveling the most efficient paths to their destinations. If a link between two routers fails, the sending router can determine an alternate route to keep traffic moving.

Briefly discuss the role of a bridge in networking.

Answer

A bridge is a device that links two networks together. Bridges are smart enough to know which computers are on which side of the bridge, so they only allow those messages that need to get to the other side to cross the bridge. Bridges can handle networks that follow same protocols.

Briefly discuss the role of a gateway in networking.

Answer

A gateway is a network device that connects dissimilar networks. It establishes an intelligent connection between a local network and external networks with completely different structures.

In enterprises, the gateway is the computer that routes the traffic from a workstation to the outside network that is serving the Web pages. In homes, the gateway is the ISP that connects the user to the Internet.

What is the importance of router?

Answer

A router works like a bridge and can handle different protocols. A router can locate the required destination by sending traffic to another router if the destination is unknown to itself. Based on a network road map called a routing table, routers can help ensure that packets travel the most efficient paths to their destinations.

What is gateway? What does it do?

Answer

A gateway is a device that connects dissimilar networks. A gateway is actually a node on a network that serves as an entrance to another network. It establishes an intelligent connection between a local network and external networks with completely different structures.

How is a repeater different from an amplifier ?

Answer

A repeater is a device that electronically regenerates the signal it receives and rebroadcasts it. It collects the inbound packet and then retransmits the packet as if it were starting from the source station. An amplifier, on the other hand, amplifies all incoming signals, including any concurrent noise present on the network.

How is a LAN different from a MAN?

Answer

How is a LAN different from a PAN?

Answer

How is a LAN different from a WAN?

Answer

Can you term a PAN as a LAN? Why/Why not ?

Answer

No, a PAN (Personal Area Network) cannot be termed as a LAN (Local Area Network) due to their distinct scopes and purposes. A PAN covers an area of 10 meters and uses wireless technologies like Bluetooth and WiFi to connect personal devices like smartphones. In contrast, a LAN covers an area of up to 1 km and uses technologies such as Ethernet, Fiber optics, and WiFi to connect computers and printers.

Compare Mesh with Tree topology.

Answer

Compare Tree and Star topology.

Answer

Write two advantages and two disadvantages for STAR topology.

Answer

The two advantages of star topology are:

1. Ease of service — The star topology has a number of concentration points (where connections are joined). These provide easy access for service or reconfiguration of the network.

2. One device per connection — In star topology, failure of a single connection involves disconnecting one node from an otherwise fully functional network.

The two disadvantages of star topology are:

1. Long cable length — Because each node is directly connected to the center, the star topology necessitates a large quantity of cable.

2. Central node dependency — If the central node in a star network fails, the entire network is rendered inoperable. This introduces heavy reliability and redundancy constraints on this node.

Write advantages and disadvantages of bus topology.

Answer

Advantages of Bus Topology are:

1. It requires a short cable length and simple wiring, reducing installation costs and maintenance efforts due to a single data path connecting all nodes.

2. The linear architecture's simplicity ensures high hardware reliability, with all data passing through a single connecting cable.

3. Additional nodes can be connected to an existing bus network at any point along its length.

Disadvantages of Bus Topology are:

1. Fault diagnosis is difficult due to decentralized network control.

2. Fault isolation is difficult. If a node is faulty, it must be fixed at its network connection point.

3. Extending a bus-type network's backbone with repeaters might require reconfiguration.

4. Nodes in a bus network need to be intelligent to manage network access independently as they are directly connected to the central bus.

Write advantages and disadvantages of tree topology.

Answer

Advantages of Tree Topology are:

1. It uses point-to-point wiring for individual segments.
2. It is supported by several hardware and software vendors.

Disadvantages of Tree Topology are:

1. Overall length of each segment is limited by the type of cabling used.
2. If the backbone line breaks, the entire segment goes down.
3. It is more difficult to configure and wire than other topologies.

Write advantages and disadvantages of mesh topology.

Answer

Advantages of Mesh Topology are:

1. Each connection can carry its own data load.
2. It is robust and provides security and privacy.
3. In this topology, fault diagnosis is easy.

Disadvantages of Mesh Topology are:

1. Its installation and configuration is difficult.
2. Cabling cost is more for mesh topology.
3. Bulk wiring is required for mesh topology.

Write the functions of the following pieces of network hardware :

(i) Modem

(ii) Switch

Answer

(i) Modem — Modem converts digital signals to audio frequency tones which are in the frequency range that the telephone lines can transmit and it can also convert transmitted tones back to digital information.

(ii) Switch — A switch is responsible for filtering i.e., transforming data in a specific way and for forwarding packets between LAN segments. To insulate the transmission from the other ports, the switch establishes a temporary connection between source and destination and then terminates the connection once the conversation is done.

"New York Avenue" is planning to expand their network in India, starting with two cities in India to provide infrastructure for distribution of their canned products. The company has planned to set up their main offices in Ahmedabad, at three different locations and have named their offices as "Work Office", "Factory" and "Back Office". The company has its Corporate Unit in Delhi. A rough layout of the same is as shown below:

Approximate distance between these offices is as follows :

In continuation of the above, the company experts have planned to install the following number of computers in each of their offices :

(i) Suggest the kind of network required (out of LAN, MAN, WAN) for connecting each of the following offices:

1. Work Office and Factory
2. Work Office and Back Office

(ii) Which one of the following devices will you suggest for connecting all the computers within each of their office units ?

1. Switch/Hub
2. Modem
3. Telephone

Answer

(i) The kind of network required are:

1. MAN should be used as the distance between the work office and factory is 14 km, which is greater than the geographical extent of LAN.

2. LAN can be used as the distance between the Work Office and Back Office is less than 1 km.

(ii) Switch/Hub

Global Village Enterprises has following four buildings in Hyderabad city :

Computers in each building are networked but buildings are not networked so far. The company has now decided to connect buildings also.

(a) Suggest a cable layout for these buildings.

(b) In each of the buildings, the management wants that each LAN segment gets a dedicated bandwidth i.e., bandwidth must not be shared. How can this be achieved ?

Answer

(a) The cable layout for these buildings is given below:

GV1 - GV2 - GV3 - GV4

(b) A dedicated bandwidth can be achieved by using switches as it does not share the media/bandwidth among all its connected computers.

"Learn Together" is an educational NGO. It is setting up its new campus at Jabalpur for its web based activities. The campus has 4 compounds as shown in the adjacent diagram.

Center to center distances between various Compounds as per architectural drawings (in metres) is as follows :

Expected Number of Computers in each Compound is as follows :

(a) Suggest a cable layout of connections between the compounds.

(b) Suggest the placement of the following devices with justification :

(i) Repeater

(ii) Hub/Switch

Answer

(a) The cable layout for these compounds is given below:

Main compound - Resource compound - Training compound - Finance compound

(b)

(i) A repeater should be placed between the Resource Compound and the Finance Compound due to the 135-meter distance, as it is used to regenerate and amplify signals to cover longer distances without losing quality.

(ii) A hub or switch connects multiple devices within a compound, allowing them to communicate with each other and the broader network. So, there should be one hub per compound.

"China Middleton Fashion" is planning to expand their network in India, starting with two cities in India to provide infrastructure for distribution of their product. The company has planned to setup their main office in Chennai at three different locations and have named their offices as "Production Unit", "Finance Unit" and "Media Unit". The company has its corporate unit in Delhi. A rough layout of the same is shown on the right :

Approximate distance between these Units is as follows :

In continuation of the above, the company experts have planned to install the following number of computers in each of their offices :

(i) Suggest the kind of network required (out of LAN, MAN, WAN) for connecting each of the following office units :

1. Production Unit and Media Unit
2. Production Unit and Finance Unit

(ii) Which one of the following devices will you suggest for connecting all the computers within each of their office units ?

1. Switch/Hub
2. Modem
3. Telephone

(iii) Suggest a cable/wiring layout for connecting the company's local office units located in Chennai. Also, suggest an effective method/technology for connecting the company's office unit located in Delhi.

Answer

(i) The network used to connect :

1. Production Unit and Media Unit is MAN as the distance is about 15 km.
2. Production Unit and Finance Unit is LAN as the distance is less than 1 km.

(ii) Switch/Hub

(iii) Two possible cable/wiring layouts for connecting the company's local office units located in Chennai are given below:

Production Unit - Finance Unit - Media Unit

Media Unit - Production Unit - Finance Unit

Satellite links can be established for connecting the company's office unit located in Delhi.