Computing GCSE 1.3.1 Networks and Topologies

What does LAN and WAN stand for?

LAN: local area network
WAN: wide area network

What are similarities between a switch and a router?

- they both connect devices
- they receive data from the devices
- they determine the correct destination for the data
- they transmit the data to its destination

What are differences between a switch and a router?

- a switch uses MAC addresses
- A router uses IPs
- A router connects internet
- A switch connects computers

What are characteristics of a LAN?

- covers a small geographical area located on a single site
- all the hardware for a LAN is owned by the organisation using it
- LANs can be wired, fibre optic cable, or wireless, Wifi

What are characteristics of a WAN?

- covers a large geographical area connecting LANs together
- organisations hire infrastructure from telecommunications companies that own and manage the WAN
- WANs are connected with telephone lines, fibre optic cables or satellite links

What are common locations for LANs?

businesses, schools and universities

What are advantages of a LAN?

- sharing files is easier, network users can access the same files and work collaboratively
- you can share the same hardware
- the internet connection can be shared between every device connected
- you can install updates on all computers at the same time

What is a disadvantage of a WAN?

it is much more expensive to set up than a LAN

How can WANs be connected?

Using fibre or copper telephone lines, satellite links or radio links

What is a network interface controller?

An internal piece of hardware that allows a device to connect to a network

How to NICs exist?

for both wired and wireless connections

What do switches do?

connects devices in the network together

What do switches do with data?

the receive data from one device and transmit this data to the device on the network with the correct MAC address

What does a router do?

forwards packets to other networks

What do routers have a crucial role with?

on the Internet directing data in packets to their destination

Where and why are routers used?

in homes and offices to connect the LAN to the network

What do "twisted pair" cables contain?

4 pairs of copper wires which are twisted together to reduce internal interference

What are coaxial cables made from?

a single copper wire surrounded by a plastic layer for insulation and a metallic mesh which provides shielding from outside interference

What do fibre optic cables do?

transmit data as light

What are fibre optic cables?

high performance cables so they dont suffer interference and can transmit over very large distances without loss of signal quality

What are advantages to networking?

- users can share files
- users can share peripherals
-users can access their files from any computer on the network
- servers can control security, software updates and backup of data
- communication with other people

What is a NIC?

it allows a device to connect to any network

Why does a user need to connect to a domain name server?

to translate the domain into the ip address

What are disadvantages to networking?

- increased security risks to data
- malware and viruses spread very easily between computers
- if a server fails, the computers connected to it may not work
- the computer may run more slowly if there is a lot of data travelling on the network

What is a client-server network?

devices are reliant on services provided and managed by a central server

How are files and software stored with client-server?

they are stored centrally on the server rather than on individual client devices

How does the client- server relationship work?

clients send requests to the server, the server processes the request and responds

What does the server store?

user profiles, passwords and access information

What are advantages to client-server model?

- easier to keep track of files as they are all stored centrally
- easier to perform backups
- easier to install software updates

What are disadvantages to client-server model?

-expensive to set up
- requires IT specialists to maintain
- users will lose access if the server fails

What is a peer-to-peer model?

here is no server and each device provides services and files to other devices on the network

What are the devices relationship to each other in peer-to-peer?

all devices are equal

How are files stored on peer-to-peer?

on individual devices and then shared with others

What are advantages of peer-to-peer?

- very easy to maintain
- no dependency on a single computer
- cheaper to set up
- no expensive hardware required

What are disadvantages of peer-to-peer?

- less secure network
- users need to manage their own backups
- can be difficult to maintain a well ordered file store

What does bandwidth mean?

the amount of data that can be sent and received successfully in a given time

How does number of users affect network performance?

too many users or devices on the same network can cause the network to slow down if there is insufficient bandwidth for the data

How does the type of transmission media affect network performance?

- wired connections have a higher bandwidth than wireless connections
- fibre optic cables have a higher bandwidth than copper cables

What is a network?

Networks are two or more computers that are connected together, allowing them to communicate over distances

What does the error rate affect?

- less reliable connections increase the number of errors that occur when data is transferred meaning that data has to be re sent until it arrives correctly
- signal quality is dependent on the range of devices from the WAP

What is the error rate?

the number of errors that occur

What does latency mean?

the delay from transmitting data to receiving it

What causes latency?

bottlenecks in the infrastructure of a structure

What is a WAP?

it allows wireless enabled devices to connect to a network without cables

What are advantages to WAPs?

- more convenient

What are disadvantages to WAPS?

- they have less bandwidth
- security is more of a concern
- connection is sometimes not as strong or reliable

What is the internet?

A worldwide network of interconnected networks

How is the home router connected to an Internet Service Provider?

typically by telephone connection or fibre

What does DNS stand for?

Domain Name Server

What do web servers do?

- holds the data needed for the website
- deal with client requests

How does website access work?

- user types address into a web browser
- web browser sends web address to a DNS server
- DNS server sends back the corresponding IP address
- Web browser sends request to the IP address for the website

What is the cloud?

where servers can be used to store data and programs that can be accessed and used over the interent

What are advantages of the cloud?

- access any time
- access anywhere
- access from any device
- large storage capacity
- automatic backup

What is a network topology?

a given arrangement of all the elements that you need for networking

How are computers connected in a star topology?

all the devices are connected to one central switch or server that controls the network

In a star topology, what does the central switch allow?

many devices to access the server simultaneously

Are Star networks wired or wireless?

They can be both

What are advantages of star networks?

- if a device fails the rest of the network is unaffected
- it is simple to add more devices to the network
- better performance- data goes through the central devices so all devices can transmit data at once and there are few data collisions

What are disadvantages of star networks?

- if there is a problem with the switch server the whole network is affected
- in wired networks, every devices needs a cable to connect to the central switch
-Extra hardware is required

What is a mesh topology?

network devices are either directly or indirectly connected to every other device without the need for one central switch

How do mesh networks work?

the send data along the fastest route from one device to another

How are devices connected in a full mesh network?

every device is connected to every other device

What are advantages to full mesh networks?

if you get a break in any of the connections you can still route your traffic via another route

What are disadvantages to full mesh networks?

there is a lot more cabling and switch hardware required which increases costs

What is a partial mesh network?

multiple routes exist between different devices, not every device is connected to every other device

What are advantages to mesh networks?

- no single point where the network can fail
- Data can be transmitted from different devices simultaneously

What are disadvantages to mesh networks?

-Overall cost of this network is way too high
- Set-up and maintenance of this topology is very difficult

What happens on a quiet network?

there are few data collisions

What happens on a busy network?

there are more data collisions

What happens when 2 packets of data collide?

both packets of data need to be resent, this makes it seem slow but it just means that the packets have to be sent more times

What is a client?

a device capable of obtaining information from a server

What is a server?

a computer which manages access to a centralised resource

What is a peer?

something of the same status or ability

Which of the 2 ways to set up a network would be best for small number of computers and which one is better for lots of computers?

- small number and low traffic- peer-to-peer
- high number and high traffic-client -to-server

What happens when you type a URL into a web browser?

- computer queries a DNS server
- DNS server has a list of all domain names and their IP addresses
- all packets are addressed to IP addresses

What is the role of the DNS server?

A service that translates IP addresses to common names.

What is hosting?

When a business uses its servers to store files of another organisation

What happens with the web browser when someone wants to view a web page?

- web sever processes the request and prepares the data before sending it back
- the web browser then receives the data and displays the web page to the viewer