Question 1

Question 10Assertion. A router and a bridge are similar.Reason. A router works like a bridge but can handle different protocols unlike bridge.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

Assertion is false but Reason is true.ExplanationA 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.

Question 2

Question 11Assertion. Hubs and switches can be replaced.Reason. While a hub is a broadcast device, a switch is a unicast device.Both A and R are true and R is the correct explanation of A.Both A and R are true but R is not the correct explanation of A.A is true but R is false.A is false but R is true.

Accepted Answer

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

Question 3

Question 5How is a PAN different from a LAN ?

Accepted Answer

LANPANLAN stands for Local Area Network.PAN stands for personal area network.LAN covers an area of up to 1 kilometer.PAN operates within a range of around 10 meters.LANs use wired (Ethernet, fiber optics) or wireless (Wifi) connections.PANs use wireless technologies like Bluetooth, Wifi.LAN networks are used to share data, information, programs, printers, hard-disks, modems etc.PAN networks are used to transfer files including email and calendar appointments, digital photos and music etc from phones and tablets to PC and vice versa.LANs provide connectivity within an organization or building.PAN is used to provide connectivity to an individual.

Question 4

Question 7(i)Give two advantages and two disadvantages of Star topology.

Accepted Answer

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

Question 5

Question 7(iii)Give two advantages and two disadvantages of bus topology.

Accepted Answer

The two advantages of bus topology in a network are:It requires shorter cable length and has a simple wiring layout.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:Fault diagnosis and isolation is difficult.Reconfiguration is required when the network has its backbone extended using repeaters.

Question 6

Question 17Which of the following topologies is very efficient and all nodes are connected to a central hub?StarTreeBusRing

Accepted Answer

StarReason — 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.

Question 7

Question 18Internet is an example of ............... topology.StarBusMeshBus

Accepted Answer

MeshReason — 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.

Question 8

Question 1What is a network ? What are its goals and applications ?

Accepted 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 :Resource Sharing — Through a network, data, software and hardware resources can be shared irrespective of the physical location of the resources and the user.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.Reduced Costs — Since resources can be shared, it greatly reduces the costs.Fast communication — With networks, it is possible to exchange information at very fast speeds.

Question 9

Question 2Discuss and compare various types of networks.

Accepted Answer

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

Question 10

Question 3Explain various mostly used topologies.

Accepted Answer

The most used topologies are as follows: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.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.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.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.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.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.

Question 11

Question 4Discuss the factors that govern the selection of a topology for a network.

Accepted Answer

The factors that govern the selection of a topology for a network are as follows: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.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.Length of cable needed — Sometimes, length of cable must be saved. The linear bus topology network uses shorter lengths of cable.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.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.

Question 12

Question 6(i)Compare and contrast Star and Bus topologies.

Accepted Answer

Star topologyBus topologyAll the devices in the network are connected by a central hub in the star topology.All the devices in this network are connected to a single cable - which acts as the backbone.The entire network would fail in case the central hub fails in the network.The entire network would fail in case the network cable fails.It requires more cables.It requires less cables.It is linear in nature.It is non-linear in nature.It is comparatively much easier to detect faults in the system.Various devices can be added using this configuration.The network only allows the addition of a limited number of devices.Data transmission is comparatively slower.Data transmission is comparatively faster.

Question 13

Question 6(iii)Compare and contrast Bus and Ring topologies.

Accepted Answer

Bus topologyRing topologyAll the devices in this network are connected to a single cable - which acts as the backbone.All the nodes are connected in the form of a ring or loop.A new node can be easily added using a connector.The addition of a new node disrupts the whole network.The chances of data collisions are very high.The chances of data collisions are low.Failure of one node does not affect the entire network.Node failure breaks the ring and communication stops.

Question 14

Question 10What is the role of a switch in a network ?

Accepted 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.

Question 15

Question 11(i)Briefly discuss the role of a repeater in networking.

Accepted 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.

Question 16

Question 11(ii)Briefly discuss the role of a router in networking.

Accepted 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.

Question 17

Question 11(iv)Briefly discuss the role of a gateway in networking.

Accepted 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.

Question 18

Question 14How is a repeater different from an amplifier ?

Accepted 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.

Question 19

Question 15How is a LAN different from a MAN?

Accepted Answer

LANMANLAN stands for Local Area Network.MAN stands for Metropolitan Area Network.LAN covers an area of up to 1 kilometer.MAN covers an area of up to 30-40 kilometer.Example: an office, a building, a factory.Example: Cable broadband Internet Services Network of a city.

Question 20

Question 16How is a LAN different from a PAN?

Accepted Answer

LANPANLAN stands for Local Area Network.PAN stands for personal area network.LAN covers an area of up to 1 kilometer.PAN operates within a range of around 10 meters.LANs use wired (Ethernet, fiber optics) or wireless (Wifi) connections.PANs use wireless technologies like Bluetooth, Wifi.LAN networks are used to share data, information, programs, printers, hard-disks, modems etc.PAN networks are used to transfer files including email and calendar appointments, digital photos and music etc from phones and tablets to PC and vice versa.LANs provide connectivity within an organization or building.PAN is used to provide connectivity to an individual.

Introduction to Computer Networks

Assertions And Reasons

Checkpoint 91

Multiple Choice Questions

Short Answer Questions

Truefalse Questions