Networks & the Internet (Cambridge (CIE) A Level Computer Science): Exam Questions

A video doorbell is attached to the front door of a house. The doorbell uses a motion sensor to detect when a visitor walks in front of the door. When the motion sensor is activated:

• The digital camera in the doorbell starts recording a video.

• A message is transmitted to a smartphone so that the person who lives in the house can watch the video.

The doorbell also has a button that can be pressed. When the button is pressed, a message is transmitted to a smartphone to play the doorbell sound.

The videos are stored on the doorbell’s internal secondary storage device and overwritten when the secondary storage device is full.

The video doorbell allows both real-time and on-demand bit streaming.

(i) State what is meant by bit streaming.

(1)

(ii) Give two differences between real-time and on-demand bit streaming.

(2)

A bank allows customers to access their accounts using an application that they can download onto a device such as a smartphone.

The system that allows customers to access their accounts using the application is a client-server model.

Describe the roles of the different devices in this model.

A business is creating a local area network (LAN) in its office.

The business is deciding which topology to use.

Tick (✓) one or more boxes in each row to identify the topology, or topologies, each statement describes.

(5)

The LAN will connect to the internet through a router. The router has a public IPv6 address.

(i) State why the router has a public IP address.

(1)

(ii) One difference between an IPv4 and IPv6 address is that the numbers in an IPv4 address are separated by full stops and in an IPv6 address they are separated by colons.

Identify two other differences between an IPv4 and IPv6 address.

(2)

An assessment board scans exam papers and stores the digitised papers on a server. Exam markers download the digitised papers to mark. The exam markers then upload the mark for each paper.

The exam markers use software that operates as a thin-client to mark the exam papers.

Complete the table by identifying two characteristics of a thin-client.

Describe how each characteristic will be used in this software.

Data transmitted on the internet passes through multiple different systems.

(i) Describe the role of routers in the transmission of data through the internet.

(2)

(ii) Describe the role of the PSTN (Public Switched Telephone Network) in the transmission of data through the internet.

(2)

A multimedia design company has an office with a LAN (local area network). The LAN can have up to 20 devices connected with cables and other devices connected using wireless access.

The company has private cloud storage for its employees to store their work.

(i) Define the term private cloud.

(1)

(ii) Describe the benefits to the company of using private cloud storage instead of public cloud storage.

(3)

Part of the internal structure of the wired LAN is a star topology.

Explain how packets are transmitted between two devices in a star topology.

A different part of the network uses the Ethernet protocol.

(i) A collision is detected.

Describe how the collision is managed using Carrier Sense Multiple Access/Collision Detection (CSMA/CD).

(2)

(ii) Identify two drawbacks of using CSMA/CD.

(2)

The devices in the office have static private IP addresses.

State what is meant by a static private IP address.

Explain the meaning of the phrase:

BitTorrent protocol provides peer-to-peer file sharing.

A school has a Local Area Network (LAN).

The LAN connects to the internet using a router.

Describe the function of a router in a network.

Complete the following table by writing the purpose of each of these other hardware devices used to support the LAN.

The students can save their school files on a public cloud.

Identify two drawbacks of the students storing their files on the public cloud.

A new classroom is being set up with 20 computers and a switch.

Explain one advantage of implementing a star topology instead of a bus topology in the new classroom.

A Local Area Network (LAN) contains four devices:

• a router

• two laptop computers

• a server.

The server has the IP address 192.168.3.2

Explain why this is not an IPv6 address.

(i) The LAN is set up as a star topology.

Draw a diagram of the topology of the LAN.

(2)

(ii) Explain how data is transmitted between the two laptops in the LAN.

(2)

(iii) Subnetting can be used to separate a network into logical segments.

Describe two other reasons why subnetting is used in a network.

(4)

State three tasks performed by devices to deal with collisions when using the Carrier Sense Multiple Access /Collision Detection (CSMA/CD) protocol in a network.

The following incomplete table contains types of IP addresses and their descriptions.

Complete the table by writing the missing types of IP addresses and the missing descriptions.

A company sells online Computer Science courses to students in different countries. The courses are stored on a public cloud.

(i) Explain why the company uses a public cloud to store these courses.

(2)

(ii) Describe two disadvantages of storing data on a public cloud compared to storing data on a server in a Local Area Network (LAN).

(4)

An office connects its computers together using cables to form a Local Area Network (LAN). The LAN uses Ethernet.

State two features of Ethernet.

Data sent using Ethernet is transmitted in frames. Each frame is made up of several parts.

The table shows three parts of an Ethernet frame. Three cells are incomplete.

Complete the table.

A school library has one powerful computer that stores all of the library's files and manages access to them. The other computers in the library connect to that computer to use the files.

The library network uses a client-server model.

State two characteristics of a client-server network.

A school stores the addresses of the devices on its network.

One server on the network has the IPv6 address 2001:0db8:0000:0000:0000:ff00:0042:8329

Complete the table by writing the two missing values.

A company has 40 computers in one building. They are connected by cables in a Local Area Network (LAN) that uses Ethernet.

One computer sends a document to a printer on the same LAN.

Explain how the Ethernet protocol makes sure that the data reaches the correct device and arrives without errors.

A student uses a tablet computer at home. The tablet connects to the home network using a wireless connection.

Give two advantages of using a wireless connection instead of a wired connection for this tablet.

A photography club has six members. Each member owns one laptop and keeps their own photographs on it. The members meet once a week and copy photographs directly from one laptop to another.

No member of the club works in computing and the club has a very small budget.

The club uses a peer-to-peer model.

Explain why a peer-to-peer model is suitable for this club.

A news website sends video to its users over the internet using bit streaming.

Complete the table by writing Real-time or On-demand in each empty cell, to identify the type of bit streaming used in each situation.

A Local Area Network (LAN) uses Carrier Sense Multiple Access / Collision Detection (CSMA/CD).

A device on this LAN has data ready to send.

State two things the device does before the data is transmitted.

A company office has a Local Area Network (LAN) with 40 computers.

Each computer on the LAN is given a private IP address. The office network is connected to the internet using one public IP address.

Explain how giving each computer a private IP address helps to keep that computer secure.

A photography studio has a desktop computer that uploads very large image files to a server in the same building.

The studio connects this computer to the network using a cable instead of using a wireless connection.

Explain why a wired connection is more suitable than a wireless connection for this computer.

A courier company has 10 computers in one office. They are connected as a peer-to-peer network and each employee stores their own delivery records on their own computer.

The company will grow to 150 computers in the same office. Every employee will need to use the same set of delivery records, and the company must make one backup of all the delivery records every night.

Explain why the company should change to a client-server model.

A news website streams a press conference in real-time while it is happening.

The website also stores a recording of the press conference on its media server, so that users can watch it on demand at any time afterwards.

Compare the real-time bit stream with the on-demand bit stream.

The table shows the steps that devices on a Local Area Network (LAN) follow when they use Carrier Sense Multiple Access / Collision Detection (CSMA/CD).

Three steps are missing.

Complete the table.

A LAN is divided into subnets.

On this LAN, the first three groups of an IPv4 address are the network ID and the last group is the host ID.

Four devices on the LAN have the IPv4 addresses shown in the table.

Explain which of the devices B, C and D are on the same subnet as device A.

Use the terms network ID and host ID in your answer.

A public library is being refitted. Two groups of computers will use the same network:

• 30 desktop computers that are fixed to study desks and are used to search a shared catalogue

• laptops and tablets that visitors bring with them and use anywhere in the building

The library will connect the desktop computers with cables. Visitors will connect their own devices wirelessly.

Explain why each group is given this type of connection.

A company uses two types of client device.

Complete the table by writing thin-client or thick-client for each description.

A streaming service broadcasts a concert in real-time as it takes place. The service also stores a recording of the concert on its media server, so that users can watch it on demand the next day.

In both cases the data is sent to a buffer on the user's device before it is played.

Explain the differences in the way the buffer is used for the real-time stream and for the on-demand stream.

Two devices on a Local Area Network (LAN) transmit at the same time and a collision occurs. The LAN uses Carrier Sense Multiple Access / Collision Detection (CSMA/CD).

A student describes what should happen next:

"After the collision, each device should wait for exactly 5 milliseconds and then transmit the data again."

Explain why the student's method would not work, and state what CSMA/CD does instead.

A network uses copper cable in one part of the building and fibre-optic cable in another part.

State how the data is carried along a copper cable and how the data is carried along a fibre-optic cable.

A chain of clothes shops has one till in each shop. Every till operates as a thin-client and is connected to the company's central server.

When an assistant scans a product, the price of the product appears on the till and the stock level for that product is reduced by one.

Describe how the till and the server share the work of processing a sale.

A student types the following Uniform Resource Locator (URL) into a web browser to open a web page.

https://www.example.org/courses/timetable.html

Identify the protocol and the domain name in this URL.

A film is sent over the internet using bit streaming. The bit rate of the stream affects the quality of the film that the user sees.

Define the term bit rate and state the unit in which bit rate is measured.

A company sends high-quality video between its two offices in the same city. The link between the offices uses copper cable, and the video often stops while it is playing.

The company will replace the copper cable with fibre-optic cable.

Explain why this will improve the link.

A design company gives one device to each employee. The employees use video-editing software, which needs a large amount of processing.

The employees often work while travelling, in places where there is no network connection.

The company is choosing between thin-client devices and thick-client devices.

Explain why thick-client devices are more suitable for these employees.

A museum stores its web pages on a web server. One web page has the following URL.

https://www.example.com/exhibits/coins.html

Complete the table by writing the name of each part of this URL.

A company has ten computers. Each computer is used on its own and is not connected to any of the others.

State two benefits the company would gain by connecting the ten computers to form a network.

A film is streamed at a constant bit rate of 6 megabits per second.

Calculate the amount of data, in megabytes, that is transmitted in 5 minutes.

Show your working.

A company is setting up two new network links.

• Link A joins two floors of a factory office. The link must pass through a room that contains large electric motors.

• Link B joins the network to a monitoring unit that is driven around a large national park.

Complete the table by naming a suitable transmission medium for each link and giving one reason for your choice.

A college has a website. Two of its web pages have the following URLs.

Page 1: https://www.example.org/courses/timetable.html

Page 2: https://www.example.org/library/opening-hours.html

Explain what these two URLs show about where the two web pages are stored.

A photography studio has six computers. The computers are not connected to each other.

Each computer has its own printer, its own copy of the photo editing software, and its own copy of every image file the studio has produced.

Describe three ways in which connecting the six computers to form a network would reduce the costs of the studio.

A home has a broadband connection with a maximum download speed of 20 megabits per second.

Three people in the home each start watching a different film at the same time. Each film is streamed at a bit rate of 8 megabits per second.

Explain why the films will not play smoothly, and describe one change that would allow all three films to play smoothly.

A student writes this statement in a test:

'The internet and the World Wide Web are two names for the same thing.'

The statement is wrong.

State what is meant by the internet and state what is meant by the World Wide Web (WWW).

A hotel has a local area network (LAN). The computers at the reception desk are connected to the LAN by cables. Guests connect their own tablet computers to the same LAN without using cables.

(i) Name the hardware inside a tablet computer that allows the tablet to join the LAN without a cable.

(1)

(ii) Name the LAN device that receives the radio signals from the tablet computers and connects them to the wired part of the LAN.

(1)

A user types a URL into a web browser. The Domain Name Service (DNS) is used before the web page can be displayed.

State the purpose of the DNS.

A company keeps its business data on 40 separate computers. When staff need to share a file they copy it onto a removable storage device and carry it to another computer.

The company plans to connect the 40 computers to form a network.

Explain one way in which the network will improve the security of the company's data, and one way in which the network will put the data at greater risk.

Hana uses a messaging application on her phone to send a message to a friend in another country. The messaging application is not a web browser, and Hana does not open any website in order to send the message.

Explain whether Hana is using the internet, the World Wide Web (WWW), or both.

A user types the URL https://www.example.com/index.html into a web browser. The web browser checks its cache and does not find an IP address for the domain name.

Describe what happens next so that the web browser can obtain the IP address.

A local area network (LAN) in an office has 20 computers. Every computer is connected by a cable to the same switch.

One computer sends a data packet to another computer on the same LAN.

Describe how the switch sends that data packet to the correct computer.

All of the computers in one office building are connected together to form a local area network (LAN).

Describe two characteristics of a LAN.

A magazine article contains this claim:

'If the World Wide Web stopped working tomorrow, the internet would stop working too.'

Explain why this claim is wrong. In your answer, give one example of a service that would still work.

The table shows six stages that take place when a user requests a web page from a website. The stages are not in the correct order.

The first stage has been numbered for you. Complete the table by writing the numbers 2 to 6 to show the correct order of the remaining stages.

A local area network (LAN) in a college is set up like this:

• 24 computers, each connected to a switch by a cable

• one server, connected to the same switch by a cable

• one Wireless Access Point (WAP), connected to the same switch by a cable

• students use laptop computers to join the LAN without cables

Two faults are reported on different days. In each case one device has failed.

Fault 1: one computer cannot reach any other device on the LAN. All 23 other computers work normally.

Fault 2: the 24 computers can still reach each other and the server, but no laptop computer can join the LAN.

For each fault, explain which device has failed.

A LAN (local area network) and a WAN (wide area network) have different characteristics.

Complete the table by describing each characteristic for a LAN and for a WAN.

A home computer is connected to the internet over a telephone line. A modem is used to make the connection.

Describe the role of the modem in this connection.

A data packet arrives at a router.

(i) Identify the part of the data packet that the router reads in order to decide where to send the data packet next.

(1)

(ii) Identify the table that the router uses to make that decision.

(1)

A manufacturing company has a factory in each of two different countries. Each factory has its own local area network (LAN).

The two LANs are joined together so that staff in the two factories can work on the same files.

Explain why the connection between the two factories has a lower data transfer rate, and is harder to protect, than the network inside one factory.

A company has two offices in different cities. Staff in the two offices send large data files to each other every day. At present the data is sent over the PSTN (Public Switched Telephone Network). The company is considering paying for a dedicated line between the two offices instead.

Explain why a dedicated line may be a better choice than the PSTN for this company.

A local area network (LAN) has a switch and a router.

• Every computer on the LAN is connected to the switch.

• The switch is connected to the router.

• The router connects the LAN to the internet.

Tick (✔) one box in each row to identify whether the task is performed by the switch or by the router.

A researcher travels between remote sites during the day. There are no telephone lines and no cables of any kind at these sites. She connects her laptop to the internet using the cell phone network.

Describe how the cell phone network provides this connection, and give one drawback of relying on it at a remote site.

Computers A and B are on the same local area network (LAN). Both are connected to the same switch. The switch is connected to a router, and the router connects the LAN to the internet.

Computer C is on a different network, in another country.

A data packet sent from A to B does not pass through the router. A data packet sent from A to C does pass through the router.

Explain why.

A small office connects its computers using a bus topology.

Describe what is meant by a bus topology.

Six computers in a warehouse are connected using a bus topology.

Computer 1 sends a packet of data to computer 5.

Explain how the packet reaches computer 5.

A company uses cloud computing to store its files and to run its accounting software.

Define the term cloud computing.

A factory connects ten machines using a bus topology. The single cable runs the length of the factory floor.

A vehicle damages the cable at a point between machine 4 and machine 5, cutting it completely.

Explain the effect this has on the network.

Complete the description of a star topology by writing the missing word in each space.

In a star topology, every device on the network has its own cable connecting it to one ............................ device.

On a modern local area network this device is usually a ............................ , which reads the destination address of a packet and sends the packet only to the device it is addressed to.

A design company keeps all of its project files on cloud storage. An employee uses a laptop to open one of these files, makes a change to it, and then saves it.

Describe what happens to the file when the employee opens it and when the employee saves it.

A design studio has twelve computers connected in a star topology.

Explain the effect on the network of each of the following:

• the cable between one computer and the central device being damaged

• the central device failing.

An online game stores each player's saved progress using cloud computing.

A player begins a game on a computer at home. The player stops playing, and later continues the same game from the same point on a different computer in another city.

Explain how cloud computing makes this possible.

A library has a star topology local area network with fifteen computers connected to one switch.

The library plans to add ten more computers next year. It also wants to be able to find and repair network faults quickly.

Explain how the star topology meets these two requirements, and identify one problem the library must plan for.

A student stores school files using cloud computing instead of on a memory stick.

Give one benefit and one drawback of storing the files in this way.

Five computers in a research laboratory are connected using a mesh topology.

Identify two characteristics of a mesh topology.

A charity has volunteers working in five different countries. All of the volunteers need to read and update the same set of documents.

Describe three benefits to the charity of storing these documents using cloud computing.

A company is building a full mesh network to connect eight servers. Each connection joins exactly two servers.

Calculate the number of connections needed.

Show your working.

A hospital uses a full mesh topology to connect the six computers that control its patient monitoring equipment. The monitoring must keep working even if part of the network fails.

Explain why a full mesh topology is a suitable choice for these six computers.

Explain one problem the hospital would have if it later used a full mesh topology for all twenty computers in the department.

A publishing company must decide where to store its manuscripts. It can use cloud computing, or it can use storage devices that the company buys and keeps inside its own building.

Describe two drawbacks of choosing cloud computing.

State what is meant by a hybrid topology and give one example of a hybrid topology.

The table gives two descriptions.

Complete the table by writing whether each description refers to a public cloud or a private cloud.

A company's network is described in the table.

(i) Identify the topology used in Building A.

(1)

(ii) Identify the topology used in Building B.

(1)

(iii) Identify the topology of the network as a whole.

(1)

A bank stores its customer account records using a private cloud rather than a public cloud.

Explain why the bank has chosen a private cloud.

A transport company is designing the network for a new site. The site has two areas:

• an open-plan office with thirty computers used for email and word processing. Staff join and leave the company often, so computers are added and removed regularly

• a control room with four computers that track vehicles in real time. These four computers must still be able to communicate with each other if one connection fails.

The two areas will be joined together to form a hybrid topology.

Justify the choice of a suitable topology for each area.

A company runs two separate systems.

• System A holds product brochures that the company wants any member of the public to be able to download.

• System B holds the salary records of the company's employees.

The company will store one system on a public cloud and the other on a private cloud.

Explain which type of cloud the company should choose for each system.