What is a computer network?
A computer network is a number of computers linked together to allow them to share resources. Networked computers can share hardware, software and data.
What are three advantages of networking computers?
- It is easy to share documents. Different users are able to work on the same document at once.
- Only one internet connection is required as it can be shared between every device connected to the network.
- Computers can share devices (e.g. printers / scanners)
- Centralised backups can be carried out automatically.
- Easier to install software over a network than on each individual computer
- Software updates / patches can be automatically pushed out by the server to ensure that all devices are up to date.
- Users can log in to any machine connected to the LAN as accounts are stored centrally on the server.
What does WAN stand for?
Wide Area Network.
What does LAN stand for?
Local Area Network.
What is a Local Area Network
A number of computers / devices linked together to allow them to share resources over a small geographical area
Define what a Wide Area Network (WAN) is
- A WAN connects LANS in different geogrphical areas.
- The communication medium is not owned by the company
- A company usually hires the network infrastructure
What is the definition of ‘bandwidth’?
Bandwidth is the amount of data that can be transmitted
…in a given period of time.
What does the acronym mbps stand for?
Megabits Per Second.
How does bandwidth impact on the performance of a network in relation to the speed of the network?
The amount of available bandwidth has a major impact on the performance of a network. The larger the amount of available bandwidth that is available the more data that can be transmitted in a given period of time.
How does bandwidth impact on the performance of a network in relation to the type of media being accessed?
Where large media files are being streamed the amount of available bandwidth is particularly important.
Should a number of users be watching streaming HD content demand on bandwidth will be high.
If there is insufficient bandwidth this could result in a reduction of quality in the video.
How does bandwidth impact on the performance of a network in relation to the number of users
If there are a large number of users on the network the amount of bandwidth available to each user may be limited. This will result in data being transmitted at a slower rate which will slow down the performance of the network.
What are the differences between a LAN and a WAN?
A LAN covers a small geographical area whereas a WAN covers a wide geographical area.
All of the telecommunications equipment used in a LAN is owned by the organisation whereas a telecommunications company provides infrastructure for a WAN.
What is meant by the term ‘client server network’?
- All devices are connected to a central server.
- The central server receives and processes requests from ‘clients’.
- The server stores user account details and files.
What is a peer network?
- All computers have equal status
- Each device can act as a client and a server
- All devices can request and provide network services
- No additional hardware / software needed to set up this type of network
What are the differences in how a client-server network and a peer network save files?
- All files can be stored centrally
- Workers can access files from any computer
- All computers can update central databases
- Files are stored on their own computers
- Users have to log-in to the same computer every time
What are the differences in how a client-server network and a peer network back-up data?
- Backups are easily managed as these can be done centrally from the File Server
- All data is backed up in one go
- Individual computers do not need to be backed up
- All computers are responsible for backing up their own files
What are the differences in how a client-server network and a peer network deal with security?
- Centralised security
- Antivirus and firewall can be installed and configured from a central location
- Individual security may need to be installed on individual machines
What environments is a client-server network and a peer network most suitable for?
Peer-Peer is appropriate for a small number of computers and a low traffic environment
Client-server is useful for if there are lots of computers and it will be a high traffic environment.
Describe two reasons a business might choose a peer network model.
- All devices have equal status, there is no central server which makes them relatively easy to maintain.
- There is no dependence on the server. If one device fails only the information stored on that device will be inaccessible. The network will still operate without that node.
- They are relatively easy to set up without the need for a network manager.
What hardware is required to set up a network?
- Wireless access point (WAP)
- Network interface card (NIC)
- Transmission media (e.g. ethernet cable)
What is the purpose of a Wireless Access Point (WAP)?
Allows for wireless devices to connect to a network (either LAN or WAN)
What is the purpose of a router?
To transmit data between at least two different networks.
What does a Switch do in a network?
A switch is an interconnection device that connects two or more devices together and helps in solving the issue of data collisions
What is a data collision?
When two or more computers place a packet onto a network at the same time
How does a Switch resolve a data collission?
As a data packet arrives at the switch – its destination address is examined and the switch creates a direct connection to that device
What does a network interface card (NIC) do?
A network interface card allows a computer to connect to a wired network
What are the two common wired transmission medias?
- Ethernet (Cat 5e / Cat6)
- Fibre optic
Give 2 reasons why fast broadband connections use fibre optics cables are the preferred choice of transmission media?
- Fibre optic cables transmit data through light so do not suffer from electrical interference (unlike traditional copper wires)
- Data can be transmitted over very large distances without any loss of signal quality.
- They are able to transmit data at a higher bandwidth.
What is the Internet?
A worldwide collection of computer networks that are connected together (Inter-networking)
What does DNS stand for?
Domain Name System/Server
What does the DNS do?
The DNS has a list of all domain names and their associated IP addresses.
The DNS redircets human-readable web addresses (like youtube.com) to the IP addresses the websites are hosted on (like 22.214.171.124).
What a Host?
A server that stores files
What is web hosting?
Placing your website on web server so that other people can access your web site.
What is the 'Cloud'?
The cloud is a network of remote servers that provide the provision of storage of data and software (unlike storing data locally)
What are 3 benefits of cloud computing for a business?
- Any user within the business will be able to load up the files on any device in any location as long as they have a data connection and the necessary permission.
- If they runs out of storage capacity it is easy to increase.
- All of the hardware and maintenance tasks will be performed by the cloud provider, they will not have a pay for specialist staff.
- The data will be automatically backed up.
- There is no large upfront cost, They will just have to pay a regular fee for the cloud services.
What are the disadvantages of cloud computing?
Connection – You can only access data / service if there is network connection.
Security - data stored on cloud is vulnerable to security hacks.
Software - web apps tend not to have as much functionality as full software package.
Limited Storage - Storage space may be limited, whereas it is possible to purchase physical storage for local storage (e.g. external hard drive)
What is a ‘virtual network’?
A software based network.
Several virtual networks can exist on single physical network
Different groups of users can have their own virtual network
What are the benefits of a virtual network?
- Easier to maintain a network and also leads to a flexible network setup
- Machines can be added and removed from a virtual network without having to re-wire.
What is meant by the tern VPN?
A Virtual Private Network
….that can be used to send data securely over a WAN
What factors could reduce the signal strength between a device and a WAP?
- Distance from WAP
- Objects such as walls and doors
- Other electrical devices could interfere with the signal
What piece of hardware is not labeled in this picture?
How do fibre optic cables transmit signals?
Light is passed through the cable using a transmitter
What are the benefits of using fibre optic cables over traditional copper cables?
- cables are thinner, so larger quantities of cable can be joined together
- there is less interference than copper
- there is less chance of the signal degrading
What are the disadvatnages of using fibre optic cables over traditional copper wires?
- Infrastructure - A lot of the areas in the UK still only have copper wire
- Expense - it is expensive to replace copper cables with fibre optic ones
How do copper wires send signals?
How does a Browser, ISP, DNS, name server and host server work together to display a webpage?
- Enter URL into browser
- Browser requests IP address of site from ISP
- ISP requests IP address from DNS server
- DNS responds with details of the name server
- ISP asks name server for site IP address
- Name server responds with IP address of the host
- ISP sends IP address to the browser
- Browser sends request to the server hosting the site
- Server hosting the site sends across content
- Browser receives website content
- Website displayed to the user
What are the advantages of a WAN?