Communication Flashcards
Internet, cable television, telephone network, Business Ethernet network
Wired
what is a computer network?
A computer network is two or more computing devices connected together in order to share resources or communicate
LoRa loT sensor network, mobile phone network, satnav network, bluetooth
Wireless
Switch
Enables multiple wired devices to connect, and uses packet switching to direct data to the correct device
Router
Responsible for moving data from one network to another, e.g. from your home network to the internet
Network interface card (NIC)
Enables a wired network connection between a computer and another networked device
Wireless access point (WAP)
Connects to a wired network and provides wireless network radio signal for wireless devices to connect to
Why do we need to have standardisation in computing?
Standardisation allows interoperability between systems.
DHCP - Dynamic Host Configuration Protocol
Used to assign IP addresses to clients on a network
DNS - Domain Name System
Used to translate human-friendly domain names to IP addresses
Used to keep track of all of the mappings of IP addresses to domain names across the internet.
HTTP - Hypertext Transfer Protocol
Used to transfer web pages between web servers and web browsers across the internet
Responsible for retrieving information from remote servers across the World Wide Web. Primarily used to access web pages.
HTTPS - Hypertext Transfer Protocol Secure
Same as HTTP, but the data is encrypted so that it remains private
Encapsulates all of the requested information in an encrypted data stream so it is secure
FTP – File Transfer Protocol
a method of transferring and sharing files across the internet. Often used by web developers to upload their web pages from their computer to the web server.
Used for transferring and sharing files across the internet.
SMTP – Simple Mail Transfer Protocol
used when an email client application wants to send an email
Used when an email client application wants to send an email to an email server.
POP – Post Office Protocol
responsible for the retrieval of emails by an email client from the email server to the local client application.
IMAP – Internet Message Access Protocol
responsible for the retrieval of emails from email servers by email client applications. Normally leaves the email on the email server.
a network protocol is…
a set of rules that
Determine how information is transmitted between two clients
Set out what order the exchange should happen in
Determine what clients should do if they encounter an error
Network speed/capacity
Measured in bits per second — bps
1 gigabit per second or 1073741824 bps
What is happening at the most basic level when computers send information from one to another across a copper wire?
Wired — electrical signals
Fibre-optic — light signals
Wireless — radio signals
Circuit switching-Pros?
More reliable — dedicated connection
Less chance of congestion
Circuit switching-Cons?
Possible wasted bandwidth
Expensive — more connections needed
Packet switching-Pros?
Bandwidth used efficiently
Packets can be redelivered
Packets can take different routes around congestion
Packet switching-Cons?
Data can take longer to be received
Packets can be lost
Less secure — packets must contain source and destination addresses
Link Layer stuff
Electrical signalling
Flow control
Error detection
Network addressing — MAC addresses
Transmitting datagrams between internet layers
Internet layer stuff
IP header
IP data
Sending and receiving IP addresses
Host-to-host routing and addressing
Transport layer stuff
Protocol header and data
Host-to-host communication
UDP — connectionless
TCP — connection-
oriented
Application layer stuff
Data we want to transmit
Application protocol — DNS, HTTP, etc.
Prepares application protocols to move to transport layer
What are the four layers?
Link, Application, Transfer, Internet
