1.4 Networks Flashcards
What are the two types of networks?
LAN(local area network)
WAN(wide area network)
How are networks useful?
- use networks daily
- use them to read emails, to message friends and family
- vital part of our use of technology, increasingly important
What’s a definition of a LAN and what’s an example?
-computers are connected together over a small geographical area such as a single building or single site
E.g. Home network, school network, network in a shop
What’s a definition of a WAN and what’s an example?
-computers are connected over a large geographical area, a WAN is a network that connects LANs with leased lines(rented phone lines)
E.g. The biggest example of a WAN is the internet which is a global connection of networks
What are the differences between a LAN and a WAN?
LAN-has it’s own infrastructure of cabling and network hardware due to distance and practicalities
WAN-uses external hardware and external infrastructure e.g.use of satellites, phone lines, The Internet
What’s a network?
A network is a collection of independent computers/devices connected together
What are the seven advantages of networking?
- able to share peripherals
- share files
- users can log onto any computer
- centralised backup
- centralised software installation
- increased security over the network
- anti-virus software can be applied centrally
How is being able to share peripherals an advantage of networking?
Printers/scanners can be shared so you only have to buy one for a group of computers to share
How is being able to share files an advantage of networking?
It allows you to access many files on any device that you need if your computers are in a network so you don’t have to individual download the file you need onto that specific computer
How is being able to log on to any computer an advantage of networking?
When work is saved centrally you don’t have to access the same computer again to access that work, this gives flexibility to a large organisation
How is being able to do centralised backup an advantage of networking?
You don’t have to do a back up on each individual machine, you can back up all the files on the network from one place
How is being able to perform software installation an advantage of networking?
It can be installed centrally rather on each individual device on the network
How is security an advantage of networking?
Usernames and passwords can protect the work in your area of the network/ the network manager can give users different access rights
How is anti-virus software an advantage of networking?
This can be applied centrally and can be kept up to date centrally
What does the piece of hardware NIC stand for and what’s its purpose?
NIC-network interface card
It has a unique MAC address which allows the specific device to be identified, it’s built into your PC into the motherboard, it lets you plug an Ethernet cable into your PC
What is the piece of hardware the repeater’s purpose?
Repeater-Boosts the signal(signal strength drops over distance, this allows for longer distances)
What are three sets of hardware which connect a network?
Hub
Bridge
Switch
These all connect devices in a network but in different ways
What does the piece of hardware WAP stand for and what’s its purpose?
WAP-Wireless Access Point
It connects devices wirelessly. Wi-Fi uses radio waves to send and receive data it doesn’t need any cables
What is the purpose of the router(hardware) in a network?
You need a router to connect separate networks
A router can connect two networks even if they have slightly different protocols
Routers can connect to other routers to make an even wider network
Connects to the internet
What’s the purpose in a modem in a network?
It switches analogue and digital signals for connection to the internet across telephone cables(modulator/demodulator)
What does a hub do in network?
- Hub sends to all devices
- sends data to all the PCs only the one with the right MAC address will accept it
What are the disadvantages of a hub in a network?
- lots of possible data collisions
- slows down the network
What does a bridge do in a network?
A Bridge splits the network into smaller regions
- sends data to the right segment
- uses a table to find which segment has the MAC address in
What are the advantages of a Bridge?
- fewer collisions
- network is quick than a hub
What does a switch do in a network?
- a switch only sends data to the correct MAC address
- table of MAC addresses assigned to each port
What are the advantages of a switch?
- least collisions-fastest performance
- bandwidth not shared because of dedicated connections
What are the advantages of a peer-to-peer network?
- all devices are equal
- hub or switch can connect computers
- easier to manage with a smaller network
- simple to set up and flexible(you can decide what software and which files go where)
What are the disadvantages of a peer-to-peer network?
- security is up to each user
- PCs can become slow when accessed by other machines
- if you want to access another machine on the network it has to be turned on
- each machine has to be backed up individually
- control is more difficult because of the individual nature
What are the different types of servers you can have?
File server Print server Web server Mail server Application server
What are the advantages of a client server?
- works for medium to large size networks
- a main computer acts as a server, providing services to others
- centralised system so back ups and security are simpler
- PCs aren’t slowed down because others won’t be accessing them
- software upgrades can be done centrally
What are the disadvantages of a client server?
- need a network manager to supervise and set up the system
- more complicated infrastructure
- server failure can disrupt all users
What is a VPN and what are the advantages?
VPN-virtual private network
-it’s using the internet(public cables) to connect remotely
Advantages
-uses encryption to protect data from unauthorised users
-don’t have to pay for leased lines, just use the internet(public lines)
What different hardware can you use for a LAN?
- wireless access points
- routers
- switches
- hubs
- network interface card
- transmission mediacables
What are some comparison notes between a hub and a switch?
Hub Higher risk of data collisions Security risks because it send information to all computers Less expensive Switch Lower risk of data collisions More secure because it only sends information to the specific computer More expensive
What are the pros and cons of using fibre optic cabling?
Pros -higher bandwidth -thinner and lighter and safer and more secure Cons Expensive to install Can break if bent too sharply or cut
What’s the internet?
A worldwide collection of computer networks
What’s an ISP?
Internet Service Provider
What’s the process of hosting?
- to let people see a web site it needs to be on a web server this is known as hosting
- then you’d select a domain name
- then you’d Register this domain name with a domain registrar
- the domain registrar checks that the domain name is unique and is associated with an IP address this is then registered on a DNS
What does http mean?
It tells the computer to use the hypertext transfer protocol which puts the packets together to be used in a web browser
What does www mean?
It tells us that it’s a web page and it’s located on the World Wide Web
What happens when you type in a URL?
-the computer will query a DNS server
-the DNS has a list of domain names and their corresponding IP addresses
-all packets are transmitted as IP addresses
This is the role of the DNS server
What’s the cloud?
- the cloud is a network of servers(servers to run applications, severs to store data)
- internet based storage or services that are not installed on your computer
- the cloud can increase storage
- the cloud can access files from anywhere in the world
What’s a virtual network?
A virtual network is when a LAN is used but software can be used to split the network into separate sections
-They share the same network hardware just some can access more information and files and software than others
What are copper UTP cables and what are some facts about them?
Copper Unshielded Twisted Pair Band width-10mbps-100mbps Max cable length-100m Interference rating-poor Cost-cheap Bend radius-360° Security-low
What are copper STP cables and what are some facts about them?
Copper Shielded Twisted Pair Band width-10mbps-100mbps Max cable length-100m Interference rating-better than UTP Cost-more expensive than UTP Bend radius-360° Security-low
What are copper coaxial cables and what are some facts about them?
Coaxial Cables-single copper conductor with a shield
Band width-10mbps
Max cable length-200m-500m
Interference rating-better than twisted pair wires
Cost-costs more than twisted pair wires
Bend radius-360°
Security-low
What are copper fibre optic cables and what are some facts about them?
Fibre optic cables-optic medium transmits light through a glass/plastic tube Band width-100Mbps-1Gbps Max cable length-2km-100km Interference rating-very good Cost-most expensive Bend radius-30° Security-high
What are factors which affect the performance of a network?
- Bandwidth
- Sharing Bandwidth-contention ratio the amount of users to available bandwidth
- Transmission media-cat-6 cables are faster than cat-5 cables, fibre optic cables are even faster
- Latency-delays in the network due to problems
- Wifi performance-interference from the same radio wave frequency
What’s a client server?
A network which relies on a central server, all devices request services from the server
What’s a peer to peer network?
- all computers are equal
- each device acts as a client and a server
- no additional hardware needed to set up
What’s the roles of devices in a client server network?
- network relies on a central server
- all clients(devices) request services from the server
- additional hardware is needed
What’s the roles of devices in a peer to peer network?
- all computers have equal status
- each device can act as a client or server
- all devices can request and provide network services
- no additional hardware/software needed to be set up
What’re advantages of cloud computing?
- your computer storage doesn’t need to be as big
- your software is always up to date
- other people can collaborate(share/edit) your files if you wish
- files are automatically backed up for you
What’re disadvantages of cloud computing?
- have to have an internet connection
- there’s often a charge
- security of your data is out of your hands
- if stored outside of the EU then it’s not subjected to the Data Protection Act
What’s local web hosting?
And what’re advantages and disadvantages?
Installing web server software on your computer and allowing others to access it
Advantages
-low cost method
-only good if only a small number of people want to access it
-good way of testing how a site would look
Disadvantages
-lack of bandwidth
-have to always keep your PC on
-need to manage it yourself, have to have technical knowledge
What’s external web hosting?
And what’re advantages and disadvantages?
Specialist companies which holds your files on one of their servers, they maintain access to the site and have sufficient bandwidth
Advantages
-they have sufficient bandwidth
-they backup you data for you
-they provide security against unauthorised access
Disadvantages
-there’s a charge
-could have to share bandwidth with other websites kept by the company
What’s DNS?
DNS- Domain Name Server
All websites are registered in the DNS which gives them a domain (text based representation of the IP address)
-registering a domain links the IP address to the domain name(which forms part of the URL)
What’re the advantages of virtual networks?
- flexible solution
- software needed for one section can just be added to that section
- network traffic can be controlled for each section
- added security, if one section gets a virus the others will not be affected
