1.3: COMPUTER NETWORKS, CONNECTIONS AND PROTOCOLS TRE fin Flashcards
What is a LAN?
local area network
computers connected over a small area
uses own infrastructure
eg, home/small company networks
what is a WAN?
wide area network
connects computers over a large geographical area
uses third party hardware and cabling
>eg satellites, phone lines, fibre optic
eg, multi-national banking networks, internet
what is the internet?
the physical components that connect together to make a network of networks
what is the world wide web?
the software that runs on the internet (websites)
what is the cloud?
a (usually) remote compuer
why is an IP address needed?
each computer has a unique IP address which is needed to communicate with networks, etc
what is the maximum value of an IP address?
255, as 256 is a binary number
what does a domain name system (DNS) do?
allows you to type a name into your browser
this then translates the web address(URL) into an IP address
how many DNS ‘root’ servers are there and what do they do?
there are 13 DNS ‘root’ servers that hold all names and IP addresses
other DNS servers hold parts of the database
what is an ISP?
internet service provider
each one has a unique IP address and goes between your device and the internet
what is a network host?
a computer or other device connected to a network.which offers information, resources and applications to users
a host is needed to have a website
what is a domain name?
a URL
these are governed by a DNS which gives you autonomy over a small section of the internet
domain name registrars sell domain names to the public
what are the factors affecting network performance?
latency, bandwidth and error rate
what is latency?
the amount of time taken for a packet of data to get from one point to another
it is measured as the time required to get the data back to the sender
what is bandwidth?
the amount of data that can be transmitted in a fixed amount of time
it is expressed in beats per second (bps)
what is error rate?
the number of errors encountered during data transmission.
the higher the error rate, the less reliable the connection or data transfer is
what is a peer to peer network?
all computers have equal status, so all devices can act as a client or server and can provide network services
no additional hardware or software is needed for this sort of network
what is a client-server network?
relies on a central server and all clients request services from the server
additional hardware is needed- a high end, powerful server
what is needed to connect to a network?
switch
router
NIC
what does a switch do?
allows many devices to connect
redirects data packets around the network
what is a server?
the controlling computer
what does the router do?
allows access to other networks and directs data packets to and from networks
what is the NIC used for?
network interface card
used to connect to a network and contains the mac address
what is a topology?
the ‘shape’ of a network
the way in which computers are connected
what is a star topology?
all devices are connected to a central switch
usually a client server network
what is a mesh topology?
full mesh: everything is connected to everything
partial mesh: most things are connected
usually set up as peer to peer
what are the advantages of a star topology?
each machine can share resources (routers, printers, servers)
easy to add/remove machines from the network
if one machine fails, the network still works
what are the disadvantages of a star topology?
equipment (switches, server, cables) are expensive
if the switch fails, all devices lose connection
all transmissions have to go through the central switch, which can be slow
what are the advantages of a mesh topology?
faster,as data doesn’t have to run through a central switch
highly robust
data can be transmitted from several devices simultaneously
what are the disadvantages of a mesh topology?
too many stations can make it slow down or crash
expensive to set up all the connections
it is hard to add more computers
what is encryption?
a method of scrambling data to produce data that doesn’t make sense without access to the key
to read the data, the user is required to decrypt the data using the key
when using a secure site, SSL (secure socket layer) encryption is used which leads to HTTPS://
what are the TCP/IP layers?
application layer -> transport layer -> internet layer -> network access layer
what does the application layer do?
deals with the client, software and the protocols that need to be used (e.g mail, webpages)
what does the transport layer do?
creates and sequences packets on the WAN , error checks packets and establishes the connection either one to one or one to many
what does the internet layer do?
is responsible for addressing, packaging and routing functions
what is the network access layer?
places TCP/IP packets on the network medium (wifi, cables, etc)
what are the advantages of cloud?
-flexible storage
-you don’t have to purchase/ maintain expensive hardware
-the cloud provider is responsible for the security
-a cloud storage centre is more environmentally friendly than lots of individual servers
-you don’t need any network skills or maintenance workers
what are the disadvantages of cloud?
-you need a reliable internet service to do anything
-you have no direct control over the security of your data
-there can be arguments over ownership
-you may be held responsible for any data security breaches even though you have no control over the security of the data z
what is ethernet?
ethernet is a high-capacity wired network
how does wifi work?
uses radio waves to transmit data
as long as a device has a wireless NIC, it can connect to a wireless network
wifi also has its own set of rules to manage data transmission
what is bluetooth?
radio wave technology commonly used to connect devices within 10m of each other
what is the different in transmission speed between wired and wireless transmissions?
wired: fast and consistent transmission speed
wireless: typically slower than cabled connections
what is the difference between expansion of network (adding more devices) between wired and wireless transmissions?
wired: costly to add extra devices and cabling and switches may be required
wireless: easy to connect more devices, but more devices will share the same bandwidth and increase the network traffic
what’s the difference between interference in wired and wireless transmissions?
wired: copper cable can be susceptible to magnetic or electrical interference, but fibre optic cable avoids this
wireless: signals can be reduced by walls and interference from other wireless devices, this affects the connection speed
what’s the difference in signal strength between wired and wireless transmissions?
wired: ethernet cable maintains good strength under to 100m, fibre optic can be much longer
wireless: wireless hotspots are limited to a small local area and need repeater devices to expand the range
what’s the difference in security between wired and wireless transmissions?
wired: data send along cables can’t be adult intercepted
wireless: wifi signals may be easily intercepted without adequate encryption security
