Networks

Question 1

LAN

Answer 1

Local Area Network

• covers a small area on a single site e.g. Businesses, schools, uni’s + homes
• all hardware personally owned + wireless/wired

Question 2

WAN

Answer 2

Wide Area Network: e.g. Internet

• connects LANS in diff locations e.g. a business w offices in 3 diff countries
• infrastructure is HIRED as expensive, connected by tel lines, sat links/radio links

Question 3

PAN

Answer 3

Personal Network

• very short range, centred around 1 user usually e.g. phones, watches, headphones
• can use wireless tech - BLUETOOTH

Question 4

NIC

Answer 4

Network Interface Card - piece of hardware that allows a device to connect to networks

Question 5

Switches

Answer 5

Connect devices on LAN

Question 6

Routers

Answer 6

Transmit data between different networks, e.g. connect to the internet

Question 7

Fibre optic cable

Answer 7

• data transmitted as light
• high performance + expensive
• don’t suffer interference, can transmit very large distances at high bandwidth w out loss of signal quality

Question 8

Ethernet Cable (Cat 5e/Cat 6)

Answer 8

• pairs of twisted copper wires to reduce internal interference
• cheaper, decent bandwidth
• used in homes + offices to connect on LAN

Question 9

Coaxial Cables

Answer 9

• Single copper wire surrounded by plastic layer for insulation
• metallic mesh to provide shielding from outside interference
• very cheap but low bandwidth

Question 10

Networking computers advantages

Answer 10

• sharing files easier: can access same files, work on same time + copy between machines
• can share same hardware e.g. printers
• Install + update software on all computers at once
• communicate cheaply + easily (email)
• User accounts can be stored centrally so can be logged on any device on the network

Question 11

Networking computers disads

Answer 11

• expensive as lots of extra hardware needed
• vulnerable to hacking, malware can spread easily between
• dependent on servers - if they go down = disruptive
• large networks are difficult to manage
• may need to employ specialist to maintain

Question 12

WLAN’s

Answer 12

Local wireless networks (e.g. WiFi is a specific family of WLAN protocols)

Question 13

How to set up a wireless network

Answer 13

with a WAP: wireless access point - a switch that allows devices to connect wirelessly

Question 14

Benefits of wireless networks

Answer 14

• Convenient as automatic connection to network + good portability
• cheaper + better for environment due to lack of wires
• easy to add more users as no extra set up + wires

Question 15

Drawbacks of wireless networks

Answer 15

• less secure as access points usually access points are visible to ALL devices so hackers can gain access
• distance from WAP, interference from other wireless networks + obstructions can reduce signal strength = limit on how far a wireless network can reach
• generally lower bandwidth + less reliable than wired networks

Question 16

Star topology

Answer 16

• all devices connected to a central switch or server
• allows many devices to access the server simultaneously
• may be wired/wireless

Question 17

star topology pros

Answer 17

• if a device/cable fails rest of the network is unaffected
• simple to add more devices
• better performance as data goes straight to central device so devices can TRANSMIT data at the same time
• fewer data collisions

Question 18

star topology cons

Answer 18

• for wired, cable needed for each device = expensive
• switch is expensive + if it fails then whole network is affected
• max num of connections is determined by the switch so you may need to buy a new one for more connections

Question 19

Bus topology

Answer 19

• single cable ‘backbone’ cable = bus, to connect all cables
• 2 terminators placed at the ends of the bus to stop data reflecting back along the bus otherwise reflected signals cause interference = network unusable

Question 20

Bus topology pros

Answer 20

• network unaffected if a device fails
• aren’t dependent on a central switch
• relatively cheap as total length of wiring needed is much less + hardware (terminators + bus cable) is cheaper to buy AND maintain

Question 21

Bus topology cons

Answer 21

• data collisions more common = slower network as data has to re sent
• more devices = more data collisions likely = UNSUITABLE FOR LARGE NETWORKS
• to avoid data collisions, devices must wait for the bus to available = slow network
• iF bus is broken = splits network and as these splits don’t have terminators = a lot of reflected signals = shut down entire network

Question 22

protocol

Answer 22

set of rules for how devices communicate + how data is transmitted across a network
- covers how communication show start + end, how data should be organised + what to do is data goes missing

Question 23

How is data sent between networks?

Answer 23

• split into equal sized packets

- packets all contain extra info like destination + source address + a CHECKSUM = to find errors

Question 24

Advantages of using layers

Answer 24

• breaks network communication into manageable pieces = helps developers concentrate in 1 area of the network
• self-contained layers, so 1 layer can be changed independently
• Set of rules for each hardware = compatible + universal hardware + software so other brands can work w each other in the same way

Question 25

Layer 4

Answer 25

Application layer
- provides networking services to applications
HTTP, FTP, SMTP

Question 26

Layer 3

Answer 26

Transport layer
- sets up communication between 2 devices ; splits data into packets + checks that they are sent correctly
TCP, UDP

Question 27

Layer 2

Answer 27

Internet layer (used by routers)
Adds IP addresses to data packets + directs them between devices + handles traffic
IP

Question 28

Layer 1

Answer 28

Link Layer
Passes data over the physical network: responsible for how data is sent as electrical signals over cables, wireless + other hardware
- interprets signals using device drivers
WIFI , ETHERNET