Fundamentals of computer networks - Case Studies

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Define what a computer network is. (more..)

Discuss the benefits and risks of computer networks. (more..)


Describe the main types of computer network including:

  • Personal Area Network (PAN)
  • Local Area Network (LAN)
  • Wide Area Network (WAN).




PAN – only Bluetooth needs to be considered.

LAN – know that these usually cover relatively small geographical areas.

LAN – know that these are often owned and controlled/managed by a single person or organisation.

WAN – know that the Internet is the biggest example of a WAN.

WAN – know that these usually cover a wide geographic area.

WAN – know that these are often under collective or distributed ownership.

Understand that networks can be wired or wireless. Discuss the benefits and risks of wireless networks as opposed to wired networks. (more..)   Know that wired networks can use different types of cable such as fibre and copper and when each would be appropriate.

Explain the following common network topologies:

  • star
  • bus.


  Students should be able to draw topology diagrams and explain the differences between the two topologies. They should also be able to select the most appropriate topology for a given scenario.
Define the term ‘network protocol’. (more..)    

Explain the purpose and use of common network protocols including:

  • Ethernet
  • Wi-Fi
  • TCP (Transmission Control Protocol)
  • UDP (User Datagram Protocol)
  • IP (Internet Protocol)
  • HTTP (Hypertext Transfer Protocol)
  • HTTPS (Hypertext Transfer Protocol Secure)
  • FTP (File Transfer Protocol)
  • email protocols:
    • SMTP (Simple Mail Transfer Protocol)
    • IMAP (Internet Message Access Protocol).



Students should know what each protocol is used for (eg HTTPS provides an encrypted version of HTTP for more secure web transactions).

Students should understand that Ethernet is a family of related protocols rather than a single protocol. They do not need to know the individual protocols that make up the Ethernet family.

Students should understand that Wi-Fi is a family of related protocols rather than a single protocol. They do not need to know the individual protocols that make up the Wi-Fi family but they should know that Wi-Fi is a trademark and that the generic term for networks of this nature is WLAN.

Understand that computers use binary to represent all data and instructions. (more..)   Students should be familiar with the idea that a bit pattern could represent different types of data including text, image, sound and integer.
Understand the need for, and importance of, network security. (more..)    

Explain the following methods of network security:

  • authentication
  • encryption
  • firewall
  • MAC address filtering.



Students should be able to explain, using examples, what each of these security methods is and when each could be used.

Students should understand how these methods can work together to provide a greater level of security.

Students should understand that MAC address filtering allows devices to access, or be blocked from accessing a network based on their physical address embedded within the device’s network adapter.


Describe the 4 layer TCP/IP model:

  • application layer
  • transport layer
  • network layer
  • data link layer.

Understand that the HTTP, HTTPS, SMTP, IMAP and FTP protocols operate at the application layer.

Understand that the TCP and UDP protocols operate at the transport layer.

Understand that the IP protocol operates at the network layer.



Students should be able to name the layers and describe their main function(s) in a networking environment.

  • Application layer: this is where the network applications, such as web browsers or email programs, operate.
  • Transport layer: this layer sets up the communication between the two hosts and they agree settings such as ‘language’ and size of packets.
  • Network layer: addresses and packages data for transmission. Routes the packets across the network.
  • Data link layer: this is where the network hardware such as the NIC (network interface card) is located. OS device drivers also sit here.

Teachers should be aware that the network layer is sometimes referred to as the Internet layer and that the data link layer is sometimes referred to as the network interface layer. However, students will not be expected to know these alternative layer names.



Case Studies

From what I have seen, it may be the case that you might be asked a question of the following type.

You will be given a scenario and asked your opinion about the networking components or the cabling arrangement required for a secure solution. You may be asked to suggest alternatives and then express an opinion as to the best solution, giving your reasons.

"Always read the question carefully!"

There are 6 case studies to try.

Case Study 1 : Bronco Brian Gunn

Bronco Brian Gunn grew up in the fifties at the height of the Western films’ popularity. Brought up on John Wayne films and television programmes like the Lone Ranger, he became fascinated by the Wild West. At the age of ten he joined the Billericay Wild West Club that boasted forty-five members.

Bronco Brian’s crowning moment was when he won the World Quick-Draw Tournament in 1976 after being National Champion for eight consecutive years. Inevitably Bronco Brian’s working life was going to be connected in some way with the Wild West.

Consequently on leaving school he opened the first of his fast-food restaurants in Billericay. The “Bronco Brian’s Burger & Beans Bars” chain of restaurants is now country wide and has over 150 outlets. At the age of 60 Bronco Brian diversified into property development, especially theme parks. He opened his first theme park in Burnham-on-Crouch and has opened four others since. He has plans to open five more.

To cope with the expanded business, a new company was founded known as BBG. Unfortunately Bronco Brian’s headquarters, The Chuck Time House, on the Billericay Business Park, was now too small for his expanded business. He has handed over the running of the restaurant chain to his son and daughter (Slim & Calamity) who remain in The Chuck Time House, while Bronco Brian has moved into a similar building, The Ranch House, on the same Business Park but 1 km away. The two buildings both have three floors and will need new networking facilities.

The Chuck Time House

In The Chuck Time House the ground and first floors are open plan. The top floor contains offices for Slim & Calamity and an office shared by their personal assistants. The assistants will both have their own PC but share a printer. Slim & Calamity will have their own laptops which will also connect to the network. There is also a boardroom/conference room which will have a standalone computer and interactive whiteboard for presentation purposes.

The first floor contains the Finance Department which consists of a manager and five assistants who will each have their own PC. There will be one printer for this department. The Marketing Department is also on this floor and consists of a manager and three assistants. They will each have a high specification computer with its own printer. A high quality colour laser printer for promotional work will be shared between them.

Half the ground floor is taken up by a reception and lounge area. The reception desk is always staffed during office opening times. There is one receptionist on duty who will have a PC and printer. The IT technicians area and server room will be housed behind the lounge area.

The Ranch House

On the top floor of The Ranch House is the corporate boardroom, Bronco Brian’s office and his secretary’s office. Bronco Brian and his secretary will each have a PC and printer. On the first floor is the Corporate Finance Department and the property managers. The Corporate Finance Department has a manager and three assistants who will each have a PC. There will be one printer for this department. The four property managers will each have their own laptop which will need to connect to the network. There will be one printer for this section.

On the ground floor is a small reception area and an office for a web designer. The receptionist and web designer will each have their own PC and printer. Also on this floor is the Human Resources Department and the Legal Department. In the Human Resources Department there is one manager and two assistants. Each will have their own PC but will share a printer. The manager of the Legal Department prefers to use his own laptop which will need to be connected to the network. His two assistants will each have their own PC. There will be one printer for this department.

Your project

Bronco Brian Gunn’s empire has an old mainframe system which was installed back in the 1970s. Now he has moved to a new building he wants a complete review of his computing facilities. You have been brought in as a network consultant to advise and help implement the installation of a new network for The Chuck Time House and The Ranch House.

Activity 1 - Work out how many PCs and Laptops are mentioned in the description given above.

Activity 2 - Advise Bronco Brian regarding the possible methods of connecting the two buildings together in a single network and suggest which you consider to be the best method, giving reasons.

Activity 3 - There are three possible methods of connecting a laptop to a network; a network cable, a wireless connection and a docking station. Consider the pros and cons of each method and suggest with reasons which Bronco Brian should use.

Case Study 2 : Laura Elle Range of Perfumes

Laura Lewis and Steven Gee met whilst employed by a clinical research organisation in Bracknell. The basis for their business partnership happened largely by accident. Steven was working on the development of a new allergy tablet. He was carrying out an experiment when Laura, from marketing walked past and complimented him on his aftershave. Steven was quite surprised by this as he did not use aftershave and so he called her back. After a while they realised that the aroma was coming from a test tube containing a mixture of chemicals.

Laura was quick to see the possibilities of marketing the mixture as a perfume. She persuaded Steven that this was a good idea and asked him to conduct further experiments. Steven created a laboratory in his garage and the pair bought the chemicals between them. Over the next few weeks Steven experimented with the chemicals in the original mix and in the end he came up with some recipes for perfumes.

Laura then approached a large department store chain which agreed to stock the Laura Elle range of perfumes. Encouraged by this, Laura and Steven are now preparing for larger scale production. Steven’s garage is too small for that level of production, so they have rented a building in the newly opened Bracknell Science Park and started trading as Laura Elle.

The building is 15 metres wide and 30 metres long and is divided into three equal sized areas by partitions across its width. Despatch is at the front of the building, warehousing in the middle, and production at the rear. The despatch area is only half the height of the building and has a staircase leading up to a balcony and three rooms. These will be used as a reception room and offices for Laura and Steven. The other areas occupy the full height of the building.

The building is well serviced with telephone points, power sockets, and cable ducts, but there are no data cables or data points. A fibre optic Internet connection is included in the rent. This terminates at a sealed box near the foot of the staircase. The box has a single RJ45 socket. The Science Park management have given Steven a leaflet explaining how his Internet connection works.

The leaflet says that he:

  • has been allocated a public Class C address of
  • may use any private Class C address on his own network

Laura and Steven will be employing warehouse, despatch, and office staff once they move into the building.

Laura and Steven are competent computer users but their network experience is limited.

For example, they are able to plug a network cable in or connect to a WiFi system with a laptop.

Your project

You have been asked to advise Laura and Steven about networks and to design a suitable system for Laura Elle.

In discussions with Laura and Steven you find out their immediate requirements are a:

  • networked PC and printer in each of the three upstairs rooms
  • networked PC and printer in the despatch area
  • networked PC and printer in the warehouse area
  • facility to connect visitors’ laptops to the system while they are in the building
  • facility for Steven to use the Laura Elle network through a Virtual Network from his home PC
  • facility for Laura to use the Laura Elle network through a Virtual Network from her laptop both at home and during sales trips.

You are also told that their main concerns are cost, security, and reliability.

You have visited the building with Laura and Steven and are familiar with its layout. You may assume that the power system is adequate and that there are sufficient cable ducts, power points, spaces for data points, and mounting points for installing equipment.

Activity 1 - Explain to Laura and Steve what a "Virtual network" is.

Activity 2 - Explain to Laura and Steve what a "Class C address" is.

Activity 3 - Explain to Laura and Steve the benefits of including a firewall in their network plan.

Case Study 3 : Deer Valley Railway

In the 1960s the government owned the entire rail network. At that time there was a movement of both passengers and freight away from rail and onto the road, which made some routes unprofitable. As a result a large number of railway lines were closed. The closures were mainly branch lines through rural areas where the number of passengers could not justify keeping the stations on those lines open.

A number of these disused lines were bought by groups of steam train enthusiasts who restored the lines. They bought and restored old steam engines and passenger carriages and ran the lines as tourist attractions. One of these lines runs through the Surrey countryside and is known as the “Deer Valley Railway” because of the number of deer which can be seen around the area. The first line was opened in 1974 and was called the Daffodil line. A large number of volunteers ensured that the track was in good order, drove the trains, sold tickets and maintained the station buildings. By 1979 two other lines, the Tulip and Hyacinth lines, had opened. The Deer Valley Railway has been running as a very successful tourist attraction ever since.

Map of the Deer Valley Railway

Recently a large number of housing developments have been built along the Daffodil line. Many residents of the developments have taken advantage of the Daffodil line because it links with a mainline service to London from Broughton Park. It was felt that a team of volunteers, no matter how dedicated, could not manage the increased number of passengers. Consequently, the “Deer Valley Railway Company” (DVRC) was set up and permanent employees now run the railway on commercial lines.

The DVRC was set up as a ‘not for profit’ company, so that revenue generated by the Daffodil line could be used to support the ongoing restoration of trains, buildings, and infrastructure of the three lines. The Tulip and Hyacinth lines are still run by volunteers and the manager of each line sits on the board of the DVRC. There are no immediate plans to run the Tulip and Hyacinth lines commercially.

The Deer Valley Railway is still using equipment from the days of steam trains. The only exceptions being a modern signalling system and a private digital telephone network. Both of these use trackside cables and are maintained by signals and telecoms specialists from the team of volunteers. The telephone exchange is at Broughton Park and the telecoms specialists are familiar with both DSL and ISDN technology.

The volunteers have installed at least one PC and printer at each station but there is no network and most of the IT equipment is second-hand and quite old. The volunteers use the equipment for tasks such as producing tickets, newsletters, publicity material, volunteer rosters, and tea shop menus.

All of the stations are equipped with a credit card payment terminal (chip and pin). The terminals are linked to the credit card system through a standard telephone line at each station.

The new General Manager of DVRC is George Harwell. He is 60 years old and has worked in the rail industry for over 40 years. He has a good knowledge of some specialised areas of IT such as signalling and control technology. He has used networks before but has little knowledge of how they are set up or managed, and expects such things to be handled invisibly by technical staff with a minimum of fuss for the user.

George has an office at the Broughton Park station.

Other staff based at Broughton Park are:

  • the Senior Engineer, who has an office in the engine shed
  • the Accountant, who shares an office with the Personnel Officer
  • two secretaries, who share an office and undertake administrative work for anyone at Broughton Park who requests their services
  • the Receptionist
  • the Station Master, and an Assistant Station Master who share an office adjacent to the booking office.

Everyone will need their own PC.

Bulk and high quality printing at Broughton Park will be done on a shared colour laser printer. Black and white printers will be needed in reception and in each office for small jobs.

Each station on the railway will need a PC and printer in the booking office, with a connection to one of the existing credit card payment terminals.

Your project

You are an I.T. consultant and have been hired by George Harwell to help him to modernise all three lines of the DVRC. You will advise George on I.T. matters and also produce reports for submission to the board of the DVRC.

In discussions with George, you find out that his main concerns are that any system set up for the DVRC must be:

  • robust. He is aware that an item of equipment may be used by several people, including trainees and new volunteers. Things should not break easily
  • reliable. George emphasises that the DVRC is spread over many square kilometres and that he would rather spend a bit more money setting things up if it means he can save on technical staff salaries
  • easy to maintain. As for the previous point, George wants users to be able to perform routine tasks such as changing printer cartridges, rather than having to call for technical support
  • user friendly. George knows he will need I.T. staff to run things ‘behind the scenes’ but anything that ordinary users will operate must be simple to use
  • value for money. This is a lesser priority than the previous points but cost must be considered therefore you will have to justify your decisions.

Activity 1 - Explain DSL technology.

Activity 2 - Explain the term ISDN and explain why it has been replaced with broadband.

Activity 3 - The cabling that connects all of the railway buildings and equipment is owned by the railway, so what sort of network is this, a WAN or a LAN; explain your answer.

Case Study 4 : Varma Loko Railway

The government of the tropical island of Varma Loko is trying to develop the island’s tourist industry. Resorts on the coast are attracting a large number of tourists but those in the interior are struggling. The government commissioned research to find out why the interior is not doing as well. They have concluded that the prime cause of the problem is poor transportation links.

Away from the coast much of Varma Loko is mountainous and the roads are narrow and winding. There is an ongoing road improvement scheme but this will take many years to complete.

The capital city, Precipaurbo, has three rail links. Line A leads to several towns in the interior. These towns have the potential to become tourist centres. Line B goes to the airport and Line C connects the coastal resorts. The railway is single track for most of its length. This severely restricts the number of trains that can be run. The Transport Minister has decided that it will be quicker to improve the railway than to wait for the new roads to be completed.

There are a number of stations on the railway. The maximum distance from one station to the next is 20 km. Making the entire railway double track would be difficult. Instead, passing places will be created, controlled by a signal system. The passing places will be a maximum of 2 km apart.

The railway is naturally divided into sections by the stations along its length. Each section will have the same basic design and will be controlled by a station. For example, the first section on Line A is controlled by Precipaurbo Central station. The next section is controlled by the first station along the line, Sekvanta, and so on.

The basic section design is illustrated in the diagram, which shows the track between Precipaurbo Central and Sekvanta. There are 50 stations on the entire railway.

The project manager, Viro De Ordoni, has hired you to advise on IT matters. The project has a multi-million-pound budget and Viro has indicated that money and manpower will not be a problem.

You will be dealing with the installation of an IT system at Precipaurbo Central. The IT system will:

  • monitor and control the first section of track on each of the three lines;
  • provide a centralised web-based booking system for the entire railway;
  • provide administrative and booking/ticket office facilities at Precipaurbo Central; and
  • support a bookings database for the entire railway that can be accessed from any station when people book tickets.

Varma Loko Railway will need a Wide Area Network (WAN) to connect the stations and passing places. Each station already has a small Local Area Network (LAN) with an internet connection.

The WAN must be able to handle:

  • control signals to and from the control boxes;
  • telephone messages between stations; and
  • data for the bookings database.

Due to the mountainous terrain, it is essential that all communication links follow the railway track, as this will allow easier installation and maintenance.

The WAN must be:

  • self-contained, with permanent communication links;
  • secure; and
  • robust and reliable.

Activity 1 - Bearing in mind what was mentioned about the security of a web server why would you place the webserver in the DMZ?

Activity 2 - Why does each station need a LAN?

Activity 3 - Describe in outline terms how the data on a WAN can be kept safe from intrusion.

Case Study 5 : Burt the Evil Genius’s Evil Empire

Burt the Evil Genius’s Evil Empire (BEGEE) has recently purchased a redundant civil defence bunker in Hertfordshire and is converting it into ‘The Dungeon of Doom’. BEGEE already owns ‘The Forest of Fear’ in Surrey, ‘The Temple of Peril’ in Berkshire and ‘The Caverns of Menace’ in Kent.

BEGEE is a paintballing company owned by Burt Wiltshire. The company’s head office is in a small industrial unit near Slough and consists of a couple of offices and a workshop. Burt works from the head office or from his house, which is situated a few miles away. Each of the BEGEE sites has its own offices. These are connected to the head office via the Internet.

Most of BEGEE’s business is basic paintballing, where opposing teams fight each other and BEGEE provides the equipment, training and location.

BEGEE’s unique selling point is to provide an enhanced paintballing experience. A Lair has been constructed at the heart of each site. Teams pay a premium price to pit themselves against an ‘Evil Genius’ and his henchmen in order to capture the Lair. The idea has proved popular with corporate entertainment clients and Burt is expanding this aspect of BEGEE.

At first the Lairs were defended by BEGEE employees, but automation has gradually taken over. The Lairs are now protected by a large number of networked devices that trigger booby traps and automatic paint guns, which the attacking team must avoid. Burt wishes to develop the idea further in ‘The Dungeon of Doom’.

The civil defence bunker, which is being used as ‘The Dungeon of Doom’, has two levels. The layout is shown in the diagrams.

Upper Level

Lower Level

The upper level is built above ground and was used as a garage and workshop for civil defence vehicles. Burt has already had this level remodelled to his requirements. Interior walls are built of wood and plasterboard, exterior walls are thick concrete and Burt has no plans to make any further changes to the layout. The IT Centre already has an external telephone/internet connection. No other network cabling or equipment has been

All areas of the upper level will need network and internet access for mobile devices. The rest of the network design is still being discussed.

The lower level is ten metres underground and very solidly built. Changing the layout would be difficult and expensive, so Burt has decided to keep all the walls in place. Some extra doors and windows have been cut to make the layout more maze-like.

Burt has had false ceilings installed throughout the lower level to give it a more closed-in feel. This left a useful area above the ceiling, which now holds the air conditioning system and power cables. The space will also be used for any other infrastructure that is needed. No network cabling or equipment has been installed.

Burt employs IT staff at each site but would like some fresh ideas for ‘The Dungeon of Doom’ project. You have been hired to advise Burt on all IT matters for the project. This will include:

  • setting up a network for the site
  • advising on technology for Lair defence ideas
  • producing documentation for Burt and BEGEE employees.

Activity 1 - Suggest a technology that can be used to detect "intruders" (game players) coming into the lair.

Activity 2 - Why would installing network cables be difficult in this situation?

Activity 3 - Explain to Burt why it is not a good idea to have power and data cables running in the same conduit, side by side.

Case Study 6 : The Green Bay Building Company

The Green Bay Building Company was founded by David Green in 2003. David trained as an architect and has been designing houses since 1985. Over time David had become concerned about global warming and has introduced into his house designs aspects to minimise the carbon footprint of the occupiers. Unfortunately these modifications tend to make the houses more expensive to produce.

The building firm that David worked for at the time did not like the modifications as it meant less profit. As a result David was instructed to remove them from his designs.

Unable to find a building company to take on his revolutionary designs, David decided the only way he was going to get his designs accepted was if he formed his own building company.

Consequently the Green Bay Building Company was formed.

Since its inception the Green Bay Building Company has created many successful developments.

David has found that some people will pay extra if they think the house is eco-friendly and would pay even more if they thought there would be a fuel saving.

David has also pioneered the idea of intelligent housing estates. In the past there have been ‘intelligent buildings’; however David has taken this one step further and linked all the houses to a central computer. This allows the buildings to share facilities such as solar panels, wind turbines and other shared resources. At the same time, the central computer monitors various aspects of the fuel usage of each of the houses. This provides David’s company with information upon which he can base the designs of future developments. It also provides the owners with details for their Home Information Pack should they wish to sell their property. David wants all the central computers of each development to be linked to the Head Office.

David’s business has expanded at such a rate that the single floor, serviced offices can no longer hold his company. A move to new offices is to coincide with the recruitment of a number of personnel. The new offices will be in Oxford, not far from where David lives.

David’s new offices will have two floors. On the top floor will be David’s office, the offices of the
company architects and the Finance Department. In addition there will be a statistician’s office whose job it is to monitor and produce information from the remote housing estate computers.

The Finance Department will accommodate three accountants and their secretary. Each will have their own computer and they will share a printer. There will also be a fax machine and a photocopier. Both architects will have their own computer; they will each have their own printer but share a plotter for printing their plans. David has a laptop which he will connect to the network when in the offices.

The ground floor will be shared by the Administration and the IT Departments. The Administration Department will consist of 15 clerical workers who deal with planning applications and other administrative functions. Each administrator will require their own computer, and they will share three printers. There will also be a fax machine and a photocopier here. The IT Department consists of one IT technician who will have his own computer and printer. His office will be next to the server room which will contain all other equipment.

You have been employed as a network manager/designer by the Green Bay Building Company and you will share the office with the IT technician.

Activity 1 - Each development has its own computer and each development computer is linked to a central computer; what sort of network is this?

Activity 2 - Suggest the equipment that might be found in a server room.

Activity 3 - What network topology would be necessary to connect up three computers to a shared printer. Draw the alternative layouts and suggest with reasons which would be best.

3.1 Fundamentals of algorithms

3.2 Programming

3.3 Fundamentals of data representation

3.4 Computer systems

3.5 Fundamentals of computer networks

3.6 Fundamentals of cyber security

3.7 Ethical, legal and environmental impacts of digital technology on wider society, including issues of privacy

3.8 Aspects of software development

Glossary and other links

Glossary of computing terms.

AQA 8520: The 2016 syllabus

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