Topic 1 - Networks


Topic 1-Factors affecting choice of a network

Cost of the Network

  • Intitial purchasing of equipment
  • Installation and training

Size of the organisation

  • Needs can range from a small LAN to a global WAN
  • Some communications media are limited by the distance they have to travel

How the system will be used?

  • What types of applications do users require?
  • Will they need large data storage?
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Factors affecting the choice of a network

Existing Systems to intergrate

  • More often networks are not developed from scratch but need to fit in with existing systems
  • Any new network must fit in with the existing operating systems and protocols

Perfomance in terms of reliability

  • Different parts of the organisation may have different performance requirements
  • Real time e-commerce systems may require greater reliability
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Topologies - Ring

Advantages of Ring

  • Network not dependant on central computer
  • Each computer has the same access as the others so no one computer can hog the network

Disadvantages of Ring

  • If there is a break in the connection then the whole network fails
  • Faults are difficult to locate
  • It is impossible to keep the network running whilst equipment is added or removed because there is only one path for the data to follow
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Topologies - Star

Advantages of Star

  • Fault Tolerant - If one of the cables fails then the other computers can still be used
  • Load tolerant - Extra computers can be added without much loss in performance because all computers have their own path to the server
  • Easy to add extra computers - extra computers can be added without disturbing the network

Disadvantages of Star

  • Higher Cost - The large amount of cabling needed makes it more expensive
  • Dependence on the central server
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Wireless Networking

Advantages of Wi-Fi

  • Allows people the freedom of working anywhere a signal can be recieved
  • Allows inexpensive LANS to be set up without cables
  • Ideal for networks in old listed buildings where cables would not be allowed to be installed

Disadvantages of Wi-Fi

  • Wi-Fi networks have a very limited range (e.g 150ft)
  • There may be health problems in using Wi-Fi
  • There may be security problems even when encryption is used
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Peer to Peer vs Client Server Network

Cost Saving:

Peer to Peer - No server is needed so all the computers can be the same

Client Server - More expensive as servers are expensive to buy


Peer to Peer - All machines have the same status

Client Server - One machine is more important than the rest


Peer to Peer - Users need more IT knowledge

Client Server - Network manager allocates access to resources on the network

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Peer to Peer vs Client Server Network

Harder to find files:

Peer to Peer - Harder to find files which are not stored centrally

Client Server - Centrally stored files are easier to find


Peer to peer - Backups cannot be made centrally. This places the responsibility on all the users to back up their own data.

Client Server - Backups and software installation can be done centrally


Peer to Peer - There is poorer security as resources are shared

Client Server - Security is better as it is centralised and one person's responsibility

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Factors when designing security policies

The Data Protection Act puts an onus on the council to keep the information secure because of its potential for misuse

Physical Security - This involves protecting hardware and software using physical rather than software methods to restrict access to the computer equipment or the sotrage medium (Locks, guards, biometric methods)

Software Methods - User IDs, passwords, levels of access (e.g. who can update web pages)

Continuous investigation of irregularities - (e.g. Query any transactions that are out of the ordinary for the customer)

Operational Procedures - Including disaster recovery planning and dealing with threats from viruses, by doing backups and updating antivirus software (to help prevent and deal with loss of data)

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Remote Management

Tasks using Remote Management

Central Backup - Easier to backup data by being able to do it from one central location

Central Pool of data/documents - All staff can access data from a central pool of data

User management/Monitoring - Better moitoring (in real-time) of what all staff are using their systems for

Collaborative Working - Staff can work jointly on the same document at the same time

  • Check to see right number of licenses
  • Log off users who have forgotten to do so
  • Setting regular times for virus scanning
  • Guide users through problems
  • Take control of stations
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User Accounts and Logs

General Points

Auditing keeps a record or who has done what on the network

Allows the manager or system to manage user accounts by allocation of access levels to users

Auditing is used to identify abuses of the system by authorised staff

Auditing investigates instances of unauthorised access (hackers)

Full answer

Auditing keeps a record of:

Who is logged on (usernames)

What: Details of files accessed/programs they used

When: The times they logged on and off

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Disaster Recovery


  • Set up a budget for it (the plan)
  • Hardware can be replaced depending on how much money they have

Risk (assessment)

  • What problems could occur?
  • Likelihood of them occuring

Data (consider)

  • No business can afford to lose its data
  • Backups of all data should be regularly made. This means that the worst case scenario is that the business has to go back to the situation of the last backup and carry on from there. Backups may take a long time - often tape-streamed at night.


  • Produce procedures for minimising risks
  • Test the plan on a regular basis to make sure it is still sufficient
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Code of Conduct

Code of conduct - A set of rules and agreement drawn up by managers and their employees.


Respecting rights of others

Abiding by current legislation

Authorisation - what parts of the system they can use

Not using equipment for personal use

Protecting hardware and software from malicious damage

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Operational Procedures

Screening potential employees - Ensure staff are monitored, CRB checks

Routines for distributing updated virus information and virus scanning procedures - Ensuring virus signatures are updated daily abd distibuted around the network when a station logs in. Establish firewalls

Establish a disaster recovery programme - who does what and when, including checking the standby equipment. Backup plans, i.e how often

Logon procedures - allocating access ights etc, change password regularly

Set up auditing procedues to detect misuse - Who/what/when. Contiguous investigation of regularities, query any transaction out of the ordinary

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Misuse of facilities

Introduction of viruses - downloading games/ not keeping virus scanners up to date

Using company time for personal email - supposed to be doing other tasks

Misuse of data for their own business - setting a business up/mailing lists

Taking data from the system and not protecting it - losing laptop



Written warnings

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Legal and Moral Issues - code of conduct


Not fully informing potential customers or clients of all available facts concerning products or services

Estate Agent

Legal = Properties Act, False information in adverts

Moral = a property developer not telling his client the property has subsidence problems or a violent history

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Legal and Moral Issues - code of conduct


Informing data subjects of their legal rights and processes for complying with those rightsICT systems allow organsiations to hold data on the public
People are not always aware of their rights and not all organisations are ethical in using this data

Legal = Data Protection Act

Moral = An employee using company data to create mailing lists for his own private home business

Monitor employee emails

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