networks Flashcards
http
-used by most web browers to access website and communicate with web servers
https
-a more secure version of http that encryptes all information sent and received
pop3
-used to retrieve emails from a server
-the server holds the email until you download it,at which point its deleted from the server
imap
-used to retrieve emails from a server
-the server holds the amil until you delete it-you only download a copy
-used by most web-based email clients
lan
local area network-small geographical area like a house or office
wan
wide area network-large geographical area ,connects lans in different geographical locations
wireless
radio waves used to transmit data
bluetooth
-direct connection between 2 devices so data can be shared
-typically 10 metres
-low bandwidth compared to wifi
wifi
-can be used by multiple devices to connect to a lan at the same time
-range between 40 and 100 metres
-high bandwidth compared to bluetooth
factors affecting performance?
-bandwidth
-amount of users
-range
-physical obstructions(walls and floors primarily)
-hardware
-topology
client-server
-managed by server
-connected devices are clients
-clients send requests and the server responds
-most uses of the internet use a client server relationship
pros of client server?
easier to keep track of file as theyre stored centrally
-easier ti manage security
-reliable
-easier to perform backups and software updates
cons of client server
-expensive to set-up and maintain
-clients have dependence on server
-the server can get overloaded if there are too many clients
peer-to-peer (p2p)
-all devices are equal
-you store files on individual devices and share them with others
-you may use a p2p network at home to share files between devices, or connect devices to a printer
pros of p2p?
-easy to maintain
-no dependence on a server
cons of p2p?
-no cetnralised management-devices need their updates and security installed indivually.backups are also more complicated.
-copying files between devices creates duplicate files-its easy to lose track of whats stored where and which files are up to dat
-peer machines are less reliable and data may be lost if one fails
-machines are prone to slow down when other devices access them
star topology
-all devices are connected to a central switch or server that controls the network
-can be wired or wireless
-the central switch allows many devices to access the server simultaneously
pros of star topology?
-if a device fails the rest of the network is unaffected
-its simple to add more devices to the network
-better performance than other setups-data goes straight to the central devices so all devices can transmit data at once and there are few data collisions
cons of star topologies?
-in wired networks every device needs a cable to connect to the central switch or server.this can be expensive,eg for an office building with 50 terminals
-if theres a problem with the switch/server the while network is affected
mesh topology
-full mesh-every device is connected to each other
-partial mesh-most devices are connected to most devices
-devices send data though the fastest route of devices
pro of mesh?
-no single point where the network can fail
-if a device fails then the data will take a different route
con of mesh?
-very expensive if wired
ftp
used to access,edit and move files between devices on a network,eg to access files on a server from a client computer
smtp
-used to send emails
-also used to transfer emails between servers
