5. Computer networks Flashcards
What is a computer network.
a collection of computers that are connected together
Advantages of computer networks: (5) if u get 4 then good enough
- users can share files and resources
- users can access their files and resources from another computer on the same network
- servers can be created to centrally control a number of operations and services on a network (e.g: security and file backup)
- communications can be sent to any computer on the network
- peripherals can be shared
what is a peripheral
a device that is attached to a computer system
disadvantages of networks: (5)
- networks can be subject to security issues, allowing unauthorised access to users’ files and resources SINCE malware and viruses can easily be spread between computers and it may be difficult to take control of the issue
- (depending on the structure) if an element of the network fails, it could cause problems for the rest of the network
- high amounts of network traffic can cause a network to run slowly
- expensive to maintain
- may need to employ a server manager
what does LAN stand for, how far does it cover, and where is it used? (3)
- Local area network
- small geographic area
- home, schools, office buildings
what does PAN stand for, how far does it cover, and why is it used? (3)
- personal area network
- only a few metres
- to transfer data or share internet between devices close together
what does WAN stand for, how far does it cover, what is it made of, and where is it used? (3)
- wide area network
- large geographic area (anything from a city to several countries)
- huge, global organisations
- is often a collection of connected LANs
ownership of the three forms of network? (3)
LAN: owned by an individual or organisation
WAN: often under collective or distributed ownership.
PAN: owner is user of the network
are networks wired or wireless?
a) wired
b) wireless
c) both
c) both
what are the three types of cables that can be used for wired networks?
- coaxial
- twisted pair
- fibre-optic
how does a coaxial cable look like, and what is it used in mainly?
- has a central wire which is surrounded by an insulating layer
- has a final outside layer that acts as a jacket
- used in Ethernet
how does a twisted pair cable look like, and what is it used in mainly?
- two separately insulated wires which are twisted around each other
- surrounded by a sort of ‘jacket’
- most common for a network
how does a fibre-optic cable look like, what is special about it, and what is it used in mainly?
- lots of very fine glass threads inside an outer layer
- special bcos uses glass instead of cable
- is used in networks
advantages of wired (vs wireless) (8) - having 5 is enough
- Stability: They are less susceptible to interference and signal loss, providing a consistent and predictable network performance.
- Security:
Less vulnerable to hacking: Physical access is required to connect to a wired network, making it harder for unauthorized users to gain access. - Speed: Higher data transfer rates
- Reduced interference: Wired networks are not susceptible to the same types of interference that can affect wireless networks, such as electronic devices, walls, or other obstacles. This results in more consistent and reliable performance.
- Less congestion: In areas with a high density of wireless networks, there can be congestion and interference issues. Wired networks, on the other hand, can handle a higher number of connected devices without experiencing the same level of congestion.
- Lower power consumption: Wired devices typically consume less power than their wireless counterparts.
Longer Range: - Immunity to Radio Frequency Interference (RFI) and Electromagnetic Interference (EMI):
Resistance to external interference: Wired connections are less susceptible to RFI and EMI, which can affect the performance of wireless networks. This makes wired networks more reliable in environments with high levels of electromagnetic activity. - Easier Troubleshooting: The physical nature of the connections makes it easier to identify and resolve problems compared to the sometimes complex and variable nature of wireless issues.
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advantages of wireless (vs wired) (5)
- Mobility: Wireless networks allow users to connect to the internet or a local network without the constraints of physical cables. This is particularly useful for devices like laptops, smartphones, and tablets that need to move around.
- Ease of Installation: There’s no need for physical cables, which can simplify the installation process.
- Reduced Infrastructure Costs: There is no need for extensive cabling, which can result in lower installation and maintenance costs.
- No Physical Barriers: Wireless networks eliminate the need for physical cables, reducing clutter and making it easier to set up and reconfigure the network. This can be especially advantageous in environments where wiring is impractical or aesthetically undesirable.
- Quick Implementation: Wireless networks can be quickly deployed which makes them ideal for temporary networks
what is a network topology?
the physical structure of a network
what is the topology of a star network?
there is a central computer/server that all other computers are directly connected to
what is a bus topology?
- there is one central backbone of cable that every computer in the network is connected to
- at the end of the central cable is a terminator, which stops data from continuously being moved around the network
pros of star network? (3)
- if a computer fails, it has little effect on other computers (unless if it is the server)
- no data collisions
- transmission of data is fast
cons of star network? (1)
- expensive as it needs a central controlling cable and a large amount of cabling to connect each computer
pros of bus network? (3)
- The length of cable required is less than a star topology (compact)
- It is easy to connect or remove devices in this network without affecting any other device.
- Very cost-effective as compared to other network topology i.e. mesh and star
cons of bus network? (5)
- Troubleshooting individual device issues is very hard.
- terminators are required at both ends of the main cable.
- If the main cable is damaged, the whole network fails or splits into two.
- Packet loss is high.
- This network topology is very slow as compared to other topologies.
