S6 - Networks (Done) Flashcards
Why would a LAN be used ?
Local Area Network - to cover small area, all hardware is owned by organisation that uses it and they can be wired or wireless.
What is a WAN for ?
Wide Area Network - connects LANs in different locations (a business with offices in three different countries needs a WAN for all devices to connect), organisations hire infrastructure from companies because its very expensive and they can be connected using telephone lines, satellite links or radio links. The internet is the biggest WAN.
What is a PAN ?
Personal Area Network - connect devices on very short range (centred around a single user), use common wireless technology (Bluetooth) to connect devices - strong signal but very short range. PANs normally don’t require additional hardware.
What are the benefits of networking computers ?
Easier to share and work on documents collaboratively, same hardware shared between multiple devices, install and update software on all computers at once, easy to communicate across a network cheaply and user accounts can be stored centrally allowing them to log in on any device on the network.
What are the drawbacks of networking computers ?
Can be expensive to set up as need a lot of hardware, networks can be vulnerable to hacking and malware can easily spread, networks can be dependant on servers - if they crash you’re unable to access the network and large networks are difficult to manage.
What is a NIC ?
A network interface card, a piece of hardware inside a device that allows it to connect to networks - for both wired and wireless connections.
What is a switch in a network ?
They’re used to connect devices on a LAN.
What is a router ?
They transmit data between different networks - commonly used to connect to the Internet.
What is in a home ‘router’ ?
Most are in fact a router, switch and WAP all in one.
What is a WAP ?
A wireless access point, a switch allowing devices to connect wirelessly.
What determines what cable you’ll use in a wired connection ?
It will be dependant on cost, bandwidth and how far you want to transmit data.
What is bandwidth ?
The amount of data that can be sent across a network in a given time.
How fibre optic cables work ?
Transmit data as light, high performance and expensive, don’t suffer interference and can transmit over large distances at high bandwidth.
What are CAT 5e and CAT 6 cables examples of ?
Ethernet cables, contain pairs of copper wires twisted together to reduce internal interference, cheaper than fibre optic with decent bandwidth - commonly used in homes and offices.
What is a coaxial cable ?
Single copper wires surrounded by plastic layer and metallic mesh to reduce outside interference, very cheap with a low bandwidth.
How do wireless networks transmit data ?
Through radio waves - so signal can be reduced by physical objects.
What are WLANs ?
They are local wireless networks - wireless LANs, commonly referred to as wi-fi which is actually a specific family of WLAN protocols.
What is a WAP ?
A wireless Access Point - basically a switch that allows devices to connect wirelessly.
What is a hotspot ?
A location where you can connect to a WAP - not a WAP itself.
How can you set up a wireless network ?
You need a WAP the devices can connect wirelessly to, so it’s necessary for them to have wireless capability which is usually built in these days but can be done using a USB dongle - HDMI dongles are popular for TVs.
What are the benefits of wireless networks ?
They are convenient as you can automatically connect and move around, can be cheaper as there are less wires, and it’s easy to add more users without extra wires or a complex setup.
What are the drawbacks of wireless networks ?
Generally less secure as access points are visible to all devices which could allow hackers to gain access, distance from WAP, any obstructions, and interference from other signals can reduce signal strength, and have lower bandwidth and are less reliable.
What is a network topology ?
The layout of the network, the two examples we know are star and bus topologies.
What is a star topology ?
All devices are connected to a central switch or server - controlling the network, the switch allows many devices to access the server simultaneously. They can be wired or wireless.
What are the advantages of star topologies ?
If one device/cable fails the rest of it is unaffected, simple to add more devices as each is connected to the switch with its own cable, tend to have better performance than other set ups - devices connected to switch directly so they can transmit at the same time, and has very few data collisions.
What are some disadvantages of star topologies ?
Hardware - such as wires for each device connected and the switch - can be expensive, if there’s an issue with the switch or server it can affect whole network, maximum possible connections on the network is determined by the switch - if you need more connections you’d need to buy a new switch.
What is a bus topology ?
Use a backbone cable - a bus - to connect all devices with a terminator at each end to stop data reflecting back along the bus which would cause interference.
What are the advantages of a bus topology ?
Network is unaffected if one device fails, aren’t dependant on central switch to keep network running, and are relatively cheap as length of wiring needed is less and hardware needed (bus and terminators) is less to buy and maintain.
What are some drawbacks of bus topologies ?
Data collisions are common - so data has to be resent slowing network, the more devices the more likely a data collision - unsuitable for large networks, to avoid collisions devices must wait for bus to be free slowing the network, and if bus is broken it splits network into separate parts - without terminators at both ends causing reflected signals which can shut down the network.
What is a protocol ?
A set of rules for how devices communicate and how data is transmitted across a network.
What things are covered by a protocol ?
How communication between two devices should start and end, how the data should be organised and what the devices should do if data goes missing.
What format is data in when sent over a network ?
Data is split into equal sized packets - each containing extra information like destination and source addresses and a checksum - used to find errors.
What is network layer ?
A group of protocols which have similar functions.
How do layers work ?
They’re self contained - not dependent on knowing what happens in other layers to do their job, and each layer serves the one above it - doing work to accommodate for an action on the layer above.
