chapter 2

What's a wide area network

a network that covers a wide geographic scale by combining LANs

what are the pros of using a WAN

wider reach, resources like server databases can be shared, and they’re easy to expand, but it has a low transfer rate

What's a wide area network

a network that covers a wide geographic scale by combining LANs

what are the pros of using a WAN

wider reach, resources like server databases can be shared, and they’re easy to expand, but it has a low transfer rate

what are some cons of using a WAN

expensive to set up as dedicated lines and routers needed, more complex to manage, weaker security

What's a local area network

a network contained within a small building, i.e. an office, with a small geographical scale

what are benefits of a LAN

resources can be shared, it’s more secure due to it’s smaller size, it has a high data transfer rate, it has central management

what are some cons to using a LAN

hacking can affect the entire network, it’s harder to manage,the range is limited and it can depend on a single server

what are the benefits of networking computers and devices 

devices can be shared (which reduces cost), users can share files/ data, network manager can oversee networks  and apply rights or restrict access 

what are the cons of networking computers and devices 

cabling and servers can be expensive, managing a large network can be difficult, breakdown of devices can affect whole network

what are WAPs 

wireless access points, which are devices that allow devices to connect wirelessly to a network. Note: because of its limited range, places like airports would need several WAPs to ensure no interruption  

what technology do wireless access points use

spread spectrum technology or infrared

what's a client server 

a server-based network where devices (clients) request information from the main/ central server which then sends the data

what are the pros of using a client server

These are easier to expand, the server looks after storing data and has good network security as users need a username / password

what are some cons of using a client server

it’s ore expensive to set up and maintain, and if the server(s) go down, so does the network

what's a peer-to-peer model

its a network type with no central server, meaning computers are linked to each other and can store their own data.

Note, it's not suitable for scenarios with more than 10 devices 

what’s a consequence of a peer-to-peer model not having a central server

data security is weaker as there is no centre security system

what are some benefits of a peer-to-peer model

users don’t need to be authenticated, it’s cheaper, and if one node goes down the network still works

what two client types does the client-server model offer 

thin clients and thick clients 

what's a thin client 

A software that relies on a central server to perform tasks and won’t work without one. Most of the processing occurs on a remote server and needs a good/stable connection. e.g. Google docs 

pros of a thin client 

less expensive to expand and cheap devices can be used, all devices are linked to server which can offer protection against hacking/ malware and updates are done centrally

cons of thin client

high reliance on server- if server goes down/ break in communication link, devices cannot work. Start up costs are higher than for thick clients 

what can be said about thin clients’ resources

they require few, SSD and RAM

what's a thick client 

a client (device) that does some of the processing itself and the system can work offline or online. It relies heavily on local resources and is more tolerant of a slow network connection. e.g. outlook 

pros of  a thick client

more robust and clients have more control as they can store own data/ files 

what can thick clients do with local resources

store data, HDD and SSD

cons of a thick client

they're less secure as it relies on clients to keep their own data secure and each client needs to update data/ software individually 

What's a bus network topology 

all devices are connected to a single, central cable. Data only goes one way and terminators are needed at each end to prevent signal reflection.

what network type are bus network topologies

they’re typically peer-to-peer

what are the advantages of a bus network

it's easy to expand, requires little cabling, and if one node fails network continues to function

what are the disadvantages of a bus network 

if main cable fails the whole network goes down, heavy loading decreases performance of network and network is not secure since each packet passes through every node 

how are packets sent in a bus network 

each node looks at packet and determines whether packet address matches its own. If so, node accepts packet and if not the packet is ignored 

what's a star network topology 

A network that uses a central hub/ switch and each device is connected to that. The central hub/switch dictates the data and it has its own connection to each device. The network is typically client-server. 

what are the advantages of a star network 

data collisions are reduced due to the topology , more secure, easy to improve (install upgraded hub) and if one connection is broken it only affects one of the hubs 

what are the disadvantages of a star network  

initial installation costs are high and if central hub/switch fails the whole network goes down 

how are packets handled in a star network if central nod is a switch 

packets are only sent to nodes where the address matches the address in packet.

how are packets handled in a star network if central nod is a hub 

all packets are sent to all device/ node on star network. if address matches it's accepted, if not, it's ignored 

what might a star network be used for 

networks where devices are frequently added or removed, like a hospital

what is a mesh network 

A group of devices connected to each other. Every network node is connected directly to all the others. It's a type of peer-to-peer network, but very different. e.g. mesh increases a systems bandwidth. 

what are the disadvantages of using a mesh network 

large amount of cabling needed, which is expensive/ time consuming and set up/maintenance is difficult 

what are the advantages of a mesh network 

easy to identify where faults have occured, broken links don't affect other nodes, good privacy/ security and easy to expand 

how are packets handled in a mesh network 

best route is determined and each packet of data is transferred from the node that recieved it to the node closest to the destination 

what is a hybrid network

a mix of two or more different topologies

disadvantage of a hybrid network 

it’s complex to install and maintain 

advantages of a hybrid network 

can handle large volumes of traffic and it's easy to identify where fault has occurred 

what is cloud storage 

where data it stored on offsite servers. Data is stored on more than one server, allowing client to access data at any time 

what is public cloud 

the customer/client and cloud storage provider are different parties 

what are the pros of using cloud storage 

files stored on cloud can be accessed anytime/ anywhere (with access to the internet), remote back-up of data so less risk of data loss, offers almost unlimited storage capacity 

what are the cons of using cloud storage 

slow or unstable internet connection causes problems accessing data, costs will be high if large amount of storage is needed, failure of cloud storage company possible meaning risk of losing backed-up data 

what is private cloud

it’s owned by one organization and accessed by one organisation. It takes full responsibility of managing and creating the cloud on-site // connecting it to a private network

what are some benefits of a private cloud

it has good security as resources are only meant for one organisation, flexible in expansion and it can be altered to match specific requirements

what are some downsides of private cloud

it’s more expensive, buying the hardware and workers, and it’s more complex to maintain / manage

what is the public cloud

computing services provided over the internet and that are owned by a cloud service provider

what’s an advantage of the public cloud

it’s cost effective, users only pay for their own resources while the providers cover maintenance, and it can be accessed anywhere with internet

what are the disadvantages of the public cloud

security risks, breaches may expose sensitive data and limited control in customisation

how are cloud-based applications different to web-based applications 

cloud-based applications can perform tasks on local device /don't require connection at all times 

what tech does WiFi use

it uses spread spectrum technology but offers much faster data rates and better ranges/ security than bluetooth

out of infrared, microwaves and radio waves, which has the largest bandwidth?

infrared then microwaves then radiowaves 

out of infrared, microwaves and radio waves, which has the best penetration 

radio waves then microwaves then infrared

out of infrared, microwaves and radio waves, which has the best attenuation

radio waves then microwaves then infrared 

what are radio waves

they carry data wirelessly in the form of electromagnetic waves

what can be said about infrared, microwaves and radio waves 

infrared is only suitable indoors and microwaves offer the best compromise 

what does bandwidth mean

the amount of data that can be transmitted within a given time range 

while microwaves and radio waves are good for short distances, how is data transmitted globally?

Satellites. For example, signal is beamed from antenna A to the satellite, it then boosts the signal and beams it back to Earth to be picked up by antenna B.

what are the three types of cables 

twisted pair cables, coaxial cables and fibre optic cables 

what are the methods of transmission

the three cables, and radiowaves / microwaves

twisted pair cables

it has the lowest data transfer rate and suffers from the most interference. It's the cheapest option and consists of one or several pairs of copper wires 

twisted pair cables are commonly used in what?

they’re commonly used in local area networks.

what are the two types of twisted pair cables 

Unshielded (used by residential users) and shielded (used commercially). Shielded has a thin metal coil jacket to stop some external interference  

coaxial cables 

They have 80x the transmission capacity of twisted pair. It suffers from the greatest signal attenuation but also offer the best anti-jamming capabilities. It also uses copper wiring 

coaxial cables are most commonly used in what

in metropolitan area networks and cable TV companies

what does a wired network use and for what

it uses cables to connect devices , i.e. copper and fibre optic cables

what are some pros of using a wired network

faster data transfer rate, more reliable as it’s less vulnerable to interference and they’re more secure

what are the cons of a wired network

mobility is limited, initially it’s more expensive than wireless, and cables are vulnerable to damage

what does a wireless network use and for what

it uses radio waves and infrared signals (or microwaves/ satellites) to transfer data between devices

what are some pros of a wireless network

greater accessibility, the internet can be accessed from almost anywhere, better mobility, it’s cheaper and easier to install

what are some cons of a wireless network

it’s less secure, transfer speed is slower, interference via physical objects and a slower speed

what are copper cables

data is carried as electrical signals. Copper cables may contain a twisted pair

what are the pros of copper cables

safe as they have a high melting points, they can be bent or twisted without breaking, and they’re less expensive to install anf maintain

what are some cons of copper cables

they’re affected by electromagnetism, limited bandwidth meaning transfer speed may be limited, and it’s more easily intercepted

what does a fibre optic do and what are its two modes

it transfers data as light, and it can be either single mode or multi-mode

what are some pros of a fibre optic cable

it’s thinner, it can transfer data over larger distances and quicker, it’s immune to interference, and it’s more secure

what are some cons of a fibre optic cable

it's expensive, fragile, and can only transfer data in one direction

what is fibre optic single mode

when a single light source is used so it has less reflection and so is used for further distances

what is fibre optic multi mode

it’s when multiple light sources are used so there is more reflection, it’s used for shorter distances

what is a hub’s role

it connects devices to form a LAN

what is a switch

it connects devices to form a LAN and it allows multiple devices to connect to a network using a single node

what’s the difference between a switch and a hub

a switch is more secure, sending data packets to the appropriate node rather than to all of them

what’s a server

computer / system that provide service or data to computers (aka clients)

what is a repeater 

A device added to transmission systems to boost signals so they can travel greater distances without signal loss

what is a bridge 

Devices that connects two LANs that use the same protocol 

what is a router 

it connects two networks using the same protocol, and it calculates the most efficient route for packets to be sent and received

what is a gateway

it connects two networks using the same protocol and it can convert data packets from one protocol to another

what can both routers and gateways assign

private IP addresses

what is a modem 

allows computers to access the internet by converting digital data into analogue signals to travel over cable wires

what is a network interference card (NIC)

hardware that allows wire-based computers to connect to networks, i.e. the internet

wireless network interface card/controller (WNIC)

hardware that connects radio-based computers to network by using antennas to communicate with networks via microwaves

what is the WNIC infrastructure mode 

A WAP is required. The WNIC is what allows the devices to connect to the WAP. The WAP then transfers the data 

what is the WNIC ad hoc 

it allows devices to connect to each other without the need of a WAP

what is ethernet 

connects devices in a wired LAN

what can using the ethernet sometimes cause the IP addresses to do

it might cause conflict. This mostly happens when a dynamic ip address has an address already being used by a static ip address.