Computer Networks

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What is a computer network?
Is two or more computing devices connected together in order to share resources
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Give some examples of network enabled devices
Network servers
Personal computers
Tablets
Smart phones
Smart televisions
Printers
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What are the 3 types of network?
PAN (Personal Area Network)
LAN (Local Area Network)
WAN (Wide Area Network)
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What is a LAN?
Is two or more network-enabled devices connected within a fairly close geographical area
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Give some examples of where a LAN could be situated
Within a single building
such as a home or office
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Why is a Wireless Access Point connected to the network?
So that Wi-Fi devices such as laptops can connect to the network
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Give 6 advantages of a LAN network

-Logging in
-File sharing
-Backups
-Installing software
-Anti-virus and malware checks
-Data transmission
Any user can log on from any workstation and still access all of their files
Resources and files can be shared by users
Backups of files and documents can be done centrally rather than needing to do it from each machine
When software needs to be installed
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Give 6 disadvantages of LANs
Network Failure
Cost
Viruses and Malware
Slow Service
Security
Expert support required
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What 5 ways can the security of a LAN network be improved?
Passwords
Access Rights
Backups
Encryption
Installing Software
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What is a Wide Area Network (WAN)?
It connects two or more local area networks (LAN) that are in different geographical locations
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How can a WAN connect to different countries?
By use of:
Fibre optic lines, including laying undersea cables
Satellite communication links
Leased telephone lines
Microwave links
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Give 3 advantages for WANs
Allows LANs to connect to one another
Allows workers to collaborate over a wide area, even across continents
Allows files and data to be shared between LANs
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Give 2 disadvantages for WANs
Can be expensive to hire a WAN service from the telecom operator.
With a LAN, a company often has its own experts to maintain the network so any problems which arise can be addressed quickly
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What's different between a virtual network and a LAN?
A 'virtual network' is created through the use of software rather than hardware
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How does a virtual network use software?
Make use of software to divide devices on a LAN into smaller groups
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Are virtual networks flexible?
Yes, it is easy to add or remove computers from the VLAN using software. There is no need to add extra cables
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What is an advantage linked with installing software?
It is much easier to install software needed by specific groups of people
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What is an advantage linked with security?
Security is improved. If one VLAN is compromised by a virus, because the others are partitioned they will not be affected
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What does VPN stand for?
Virtual Private Network
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How do VPNs work?
They use virtual networks to connect devices to a LAN through a WAN
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How can companies use software to connect VPNs over a large geographical are?
Using software companies can enable employees to share VPNs over a large geographical area
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What is VPN tunnelling?
When all the data packets sent are scrambled (encrypted) so only that device and the company network can read them
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What is a Network Topology?
A technical term that describes the layout of connections in a network
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What are the 6 main types of topologies?
Point to Point
Star
Mesh
Bus
Ring
Tree
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What is a Star network topology?
A central device directly connected to all other nodes. Just like a star shape
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What could the central node be in a star network topology?
A hub, switch or server
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Where are star topologies most commonly used and why?
In an office or small company because it is very efficient, relatively low cost, and fairly simple to set up
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How reliable are star networks?
Very reliable, because if one connection fails, it does not affect other users
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Are data collisions frequent on a star network?
No, as each node has its own cable to the server
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What's the security like on a star network?
Good security - no workstation can interact with another without going through the server first
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How simple or difficult is it to add or remove nodes from a star topology?
Very simple, as it has no effect on any other node
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How expensive is a star topology?
The most expensive network layout to install because of the amount of cables needed
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What happens if the central switch or server fails on a star topology?
The whole network goes down
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What does a star topology require in the centre?
A high performance switch or server in the centre as all traffic passes through it
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What is a mesh network?
Where each node relays the data it receives to other nodes within reach. Unlike a star network, there is no central node in a mesh network
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Why do mesh networks have excellent wireless range?
Most of the nodes are in the wireless range and so can easily exchange data with one another
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Why are mesh networks very robust?
If one node fails, then other nodes within range allow data transmission around the network to continue
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What is advantage, in regards to data packets, for mesh networks?
Messages can be received more quickly if the route to the intended recipient is short and they should always get through as they have many possible routes on which to travel.
In simple terms, multiple connections mean each node can transmit to and receive
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What are 2 main disadvantages with mesh networks?
Full mesh networks can be impractical to set up because of the high number of connections needed.

Many connections require a lot of maintenance
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Give 4 places that a mesh network is used in
Military organisations often use mesh topologies to avoid breakdowns in communication.

Cities are increasingly using wireless mesh networks to help monitor traffic flow, sewage treatment and to help control street lighting.

Emergency services, such as p
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What is a network protocol?
Is an agreed set of rules, on how to communicate over a network. A protocol is often made formal by setting up a world standard
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What 6 details should a protocol include?
How to set up a connection
How to end a connection
How to start a message
How to end a message
How to deal with corrupted data
How to format the data being sent
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What do protocols allow hardware makers to do?
Hardware makers can make sure that their devices will work on a network using that protocol
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What does TCP/IP stand for?
Transmission Control Protocol / Internet Protocol
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What does the TCP/IP protocol do?
Prepares messages for transmission and reassembles any received messages
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When sending data, the TCP rules (protocol) include what?
Dividing the message into packets
Adding a sequence number to each packet so the message can be re-assembled
Adding extra error-correction information, so errors can be spotted and fixed
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When receiving data the TCP rules (protocol) include what?
Examining each packet for errors by using the extra information that was added to it
Fixing any errors (if possible) or requesting that the packet be re-sent
Spotting missing packets and requesting them to be re-sent
If all packets are present, using the
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When transmitting messages, what is the IP protocol responsible for?
For providing the destination address and to recognise incoming data packets
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For sending data the IP rules (protocol) include what?
Add the destination address to each data packet
Add it own address to indicate where it came from
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For receiving data packets the IP rules (protocol) include what?
Accept data packets that have its own address attached
Ignore all data packets that do not contain its own address
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What does HTTP stand for?
HyperText Transfer Protocol
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What does the HTTP protocol underlie?
World Wide Web
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What protocol is used when web pages are sent and received?
HTTP
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What does the HTTP protocol allow the browser to do?
To request individual files from a web server in an orderly way
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Other cards in this set

Card 2

Front

Give some examples of network enabled devices

Back

Network servers
Personal computers
Tablets
Smart phones
Smart televisions
Printers

Card 3

Front

What are the 3 types of network?

Back

Preview of the front of card 3

Card 4

Front

What is a LAN?

Back

Preview of the front of card 4

Card 5

Front

Give some examples of where a LAN could be situated

Back

Preview of the front of card 5
View more cards

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